taxonID	type	description	language	source
975A7812FFC9FFF8FEC779EF6956F586.taxon	description	(Figures 5, 6, 77)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC9FFF8FEC779EF6956F586.taxon	materials_examined	Type Material. Holotype (male): Australia: Queensland: Tinaroo Ck. Rd. via Mareeba, 17 ° 1 ' S, 145 ° 27 ' E, 21 October 1991, DeFaveri, Huwer, Storey. Deposited in the QMBA. Paratypes (4): Australia: Queensland: Clohesy River, slow flowing stream, sandy banks, algal growth, half sun, riverine scrub, unfresh water, 16 ° 55 ' S, 145 ° 34 ' E, 22 December 1994, P. Zborowski (2 ANIC); N. Q., 15 km NE Mareeba, MDPI intercept trap site No. 25, flight intercept trap, 16 ° 56 ' S, 145 ° 32 ' E, 7 January – 12 February 1985, Storey & Halfpapp (1 QPIM); same locality, 16 ° 56 ' S, 145 ° 32 ' E, 12 February – 20 March 1985, Storey & Halfpapp (1 QPIM). Representative specimens to be deposited in MCZ.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC9FFF8FEC779EF6956F586.taxon	diagnosis	Differential Diagnosis. Recognized by the angulate anterolateral areas of the pronotum, the dark brown to piceous dorsum, the finely sparsely punctate and shining pronotum, the comparatively short pronotum and wide body, and the elytral intervals ca. twice as wide as the weakly striate­impressed series. This species has some resemblance to G. australis and G. setosus, which also have a setal fringe on the elytral margins, but differs in shape of the pronotum, color, and male genitalia form (Figs. 2, 4, 6).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC9FFF8FEC779EF6956F586.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.89 / 0.86; head 0.37 / 0.52; pronotum 0.41 / 0.67; elytra 1.33 / 0.86. Form moderately ovate, moderately convex. Color dark brown to piceous, dorsal surface shiny, non­microreticulate. Head shiny, frons very finely sparsely punctate, sparsely pubescent; interocular foveae deep, pubescent; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength slightly less than apical width, very sparsely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length, anterior arcuate, apicomedially raised in form of very small tooth (male only). Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum markedly bisinuate, anterior angles produced more anteriorly than midline sclerotized part; each lateral depression with posterior angle produced to form small point, posterior margin concave, lateral margin setose, weakly arcuate; lateral fossulae shiny, deep, lacking microsculpture; pronotal disc moderately transversely convex, shiny, extremely finely sparsely punctate, each puncture with a recumbent seta; median groove deep, moderately wide, extending nearly to margins, tapering at ends; anterior foveae oval, deep, each separated from posterior fovea by 2 times length of anterior fovea; posterior foveae oblique, shallow, linear impressions with ill­defined margins, slightly less than 1 / 2 as long as and as wide as median groove; posterolateral angles lacking impressions. Elytra moderately transversely convex on disc, with 6 rows of punctures in weakly developed striae between suture and humeri; intervals shiny, rounded, width 1.5 – 2 x that of punctures; punctures round, separated from each other by about puncture width, each with a recumbent seta; summit of declivity near posterior one­third; sides of elytra nearly vertical in posterior 1 / 4, apices conjointly sharply rounded; stria 3 terminating into 4 at about apical 1 / 4; elytral explanate margin moderately wide, with distinctive fringe of setae. Metasternal glabrous area oval, length equal width, shining, convex. Abdominal ventrites 1 – 3 and basally 4 with hydrofuge pubescence. Aedeagus (Fig. 6): Length of main­piece 0.28 mm, length to tip of parameres 0.31 mm; lobes relatively long and slender, each with a small subapical barb; notches wide, Ushaped, narrowing slightly apically, ventral notch slightly deeper than dorsal notch; duct truncate at apex; apical paramere seta elongate, ca. 2 x length of next longest setae. Females are similar to males in form of the elytral epipleuron; the apical margin of the labrum is arcuate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC9FFF8FEC779EF6956F586.taxon	etymology	Etymology. Named in reference to the angulate anterolateral areas of the pronotum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC9FFF8FEC779EF6956F586.taxon	distribution	Distribution. Currently known from three closely clustered localities in northern Queensland (Fig. 77).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFDEFFF6FEC779E2691AF5AE.taxon	description	(Figures 1, 2, 78)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFDEFFF6FEC779E2691AF5AE.taxon	materials_examined	Type Material. Lectotype of Ochthebius australis (hereby designated; male): Australia: South Australia: Port Lincoln; [labels: " TYPE [red disc] "; " Port Lincoln, S. Australia (Blackburn) "; " Australia. Blackburn coll. B. M. 1910 ­ 236 "; " Ochthebius australis, Blackb. "; Lectotype [red] O. australis Blackburn by P. D. Perkins "; deposited in the BMNH. The type series comprises two males and one female. One male is hereby designated lectotype; I have dissected this male, and drawn the genitalia (Fig. 2). The two other specimens (on one pin) are labelled as paralectotypes and have the same locality data as the lectotype; I have dissected this male also.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFDEFFF6FEC779E2691AF5AE.taxon	diagnosis	Differential Diagnosis. Recognized by the distinctive fringe of setae on the elytral margin, the finely sparsely punctate pronotum, the narrow median groove and nonmicroreticulate foveae, and the elytral intervals wider than the serial punctures. Very similar in dorsal habitus to G. setosus (which see), but less strongly punctate and with setae on the elytra less prominent. Reliable determinations, especially of abraded specimens (e. g., the lectotype), will be based on study of the male genitalia which are similar in being strongly barbed, but differ in shapes of the lobes and especially the shape of the duct, which in G. australis is short, asymmetrical, sinuate in lateral aspect, and has a cuticular crease at the apex (Figs. 2, 4).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFDEFFF6FEC779E2691AF5AE.taxon	description	Description. Size (length / width, mm) of the lectotype: body (length to elytral apices) 1.67 / 0.73; head 0.27 / 0.44; pronotum 0.41 / 0.58; elytra 1.01 / 0.73. Form moderately ovate, moderately convex. Color brown, head darker, dorsal reliefs shining. Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal midlongitudinal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate; pubescence sparse on disc, denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length; anterior margin arcuate, with small upturned apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; arcuate setae, originating from basal sides of pronotum, on top of lateral hyaline border; anterior margin of pronotum slightly arcuate in midregion; each lateral depression with posterior in form of right angle, lateral margin distinctly setose; lateral fossulae deep, lacking microsculpture, small pit at anterior extreme; pronotal disc moderately convex, extremely finely sparsely punctate, each puncture with a fine recumbent seta; median groove shallow, narrow, extending nearly to margins, tapering at ends; anterior foveae deep, small, slightly wider than median groove, slightly elongate; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and as wide as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, sides nearly vertical in basal 0.5, with six rows of small, closely spaced punctures between suture and humeri; each puncture with a fine, short decumbent seta that nearly overlaps base of following seta; intervals flat or slightly rounded, width 1.5 ­ 2.5 x that of punctures; intervals with very sparse, erect, moderately long setae; summit of declivity near posterior 0.66, where elytra are transversely markedly convex; elytral explanate margin very narrow, with fringe of long setae. Metasternal glabrous area length equal width, suboval, shining, convex. Abdominal ventrites 1 ­ 3 and basally 4 with hydrofuge pubescence. Females have the explanate elytral margin similar to males; the anterior margin of the labrum has a small apicomedian tooth, smaller than that of males. Aedeagus (Fig. 2): Length of main­piece 0.27 mm, length to tip of parameres 0.28 mm; lobes relatively long, in ventral aspect apical width slightly greater than paramere width, each lobe with strong barb near midlength; notches U­shaped, of about equal depth and width; narrowest width of ventral notch less than greatest width of lobes; duct short, apex asymmetrical and with cuticular crease, in lateral aspect markedly sinuate; apical paramere seta elongate, ca. 2 x length of next longest seta.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFDEFFF6FEC779E2691AF5AE.taxon	distribution	Distribution. Widely distributed in a near­coastal belt from South Australia to southern Queensland; also present in Tasmania (Fig. 78). Notes. The lectotype (Fig. 1) has many abraded setae and is duller than most specimens.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFDEFFF6FEC779E2691AF5AE.taxon	materials_examined	Material Examined (1708): Australia: Australian Capital Territory: Angle Crossing, Murrumbidgee River, sandy mudflats at edge of river, elev. 595 m, 35 ° 34 ' S, 149 ° 6 ' E, 15 October 2000, N. Porch (NP 13) (4 ANIC); Black Mtn., light trap, 35 ° 16 ' S, 149 ° 6 ' E, 28 February 1968, M. S. Upton (1 ANIC); same locality, 35 ° 16 ' S, 149 ° 6 ' E, 1 March 1968, M. S. Upton (1 ANIC); same locality, 35 ° 16 ' S, 149 ° 6 ' E, 27 March 1968, M. S. Upton (1 ANIC); Canberra, L. Burley­Griffin, 35 ° 18 ' S, 149 ° 7 ' E, 30 March 1965, M. E. Bacchus (MEB 222) (36 BMNH); Canberra, stream entering L. Burley­Griffin, stream, 35 ° 18 ' S, 149 ° 7 ' E, 30 March 1965, M. E. Bacchus (MEB 221) (234 BMNH); Casuarina Sands on Murrumbidgee River, coarse sand, gravel and roots (Casuarina) at edge of riffle zone of large river; Casuarina riparian forest, elev. 475 m, 35 ° 19 ' S, 148 ° 57 ' E, 21 July 2000, N. Porch (NP 69) (20 ANIC); nr. Canberra, 35 ° 22 ' S, 149 ° 5 ' E, 28 March 1965, M. E. Bacchus (MEB 219) (3 BMNH); New South Wales: Gilgandra, 31 ° 42 ' S, 148 ° 40 ' E, 19 November 1992, C. Watts (54 SAMA); Manar Creek, Canberra­Coast Road, 35 ° 17 ' S, 149 ° 39 ' E, 18 May 1967, E. Britton & S. Misko (1 ANIC); Mudgee, 32 ° 34 ' S, 149 ° 35 ' E, 1 February 1935, H. J. Carter (2 UQIC); Rock Flat Creek, 7 mi. E of Cooma, 33 ° 48 ' S, 151 ° 12 ' E, 31 March 1965, M. E. Bacchus (MEB 223) (25 BMNH); Sydney [no date], 33 ° 52 ' S, 151 ° 12 ' E, Lea (2 SAMA); Tamworth [no date], 31 ° 5 ' S, 150 ° 55 ' E, Lea (3 SAMA); Wilbertree Flat, in pitfall trap baited with fish, damp patch near river, 32 ° 30 ' S, 149 ° 35 ' E, 28 January 1991, V. Lorimer (9 ANIC); Queensland: Braemar S. F., via Kogan, pitfall­Callitris, 26 ° 59 ' S, 150 ° 54 ' E, 1 October 1979 – 28 Febru­ ary 1980, G. B. Monteith (1 ANIC); Goondiwindi, 14 km NE, in debris at edge of pond, 28 ° 29 ' S, 150 ° 23 ' E, 25 October 1991, T. Gush (40 ANIC); Moran's Creek, 760 – 820 m a. s. l., SW of O'Reilly's Rainforest Guesthouse, Lamington NP, ca. 80 km S Brisbane [beeline], 28 ° 14 ’ 11.2 ” S 153 ° 08 ’ 01.1 ” E – 28 ° 13 ’ 59 ” S 153 ° 07 ’ 27 ” E, River (Moran's Creek), ca. 2 – 4 m wide, through dense rain forest, Eucalypt forest and open grassland, 760 – 820 m a. s. l., 24 August 2004, M. A. Jäch (AU 9) (7 NMW); Running Creek Road, SE Rathdowney, ca. 25 km SSE Beaudesert [beeline], 28 ° 15 ’ 20.2 ” S 152 ° 53 ’ 49.1 ” E, small road side ditch (remnants of small swampy meadow), 25 August 2004, M. A. Jäch (AU 12) (12 NMW); South Australia: 10 K N Forreston, 34 ° 43 ' S, 138 ° 54 ' E, 3 September 1999, C. H. S. Watts (1 SAMA); 13 km W Meadows, 35 ° 11 ' S, 138 ° 37 ' E, 26 September 1996, C. Watts (3 SAMA); Adelaide [no date], 34 ° 55 ' S, 138 ° 36 ' E, Bakewell (2 BMNH); same locality, 34 ° 55 ' S, 138 ° 36 ' E, P. D. Morris (10 BMNH); same locality, 34 ° 55 ' S, 138 ° 36 ' E, C. Watts (2 SAMA); Coolawang Ck Mt Scrub Rd, 35 ° 36 ' S, 138 ° 26 ' E, 28 October 1994, Aust. water quality centre 3515 (1 SAMA); Epsom Spr., White Flat Rd., Eyre Pen., 34 ° 31 ' S, 135 ° 51 ' E, 14 December 1976, J. E. Bishop & J. H. Diener (5 SAMA); Finniss River Braeside Rd, 35 ° 21 ' S, 138 ° 47 ' E, 3 November 1994, Aust. water quality centre 3922 (1 SAMA); Hutt River downstream of Spalding, 33 ° 35 ' S, 138 ° 36 ' E, 14 November 1994, Aust. water quality centre 3583 (1 SAMA); Inman River, near Glacier Rock, sandy mud and litter at edge of small stream in pasture, elev. 40 m, 35 ° 29 ' S, 138 ° 31 ' E, 1 January 2003, N. Porch (75) (168 ANIC); Light River Pinkerton Plains, 34 ° 24 ' S, 138 ° 38 ' E, 24 May 1994, Aust. water quality centre 3449 (1 SAMA); Marne River Eden Valley, 34 ° 40 ' S, 139 ° 6 ' E, 13 October 1994, Aust. water quality centre 3842 (1 SAMA); Marne River South of Cambrai, 34 ° 40 ' S, 139 ° 17 ' E, 12 October 1994, Aust. water quality centre 3843 (1 SAMA); Middle R. d. strm dam Lagoon Flat, 34 ° 24 ' S, 138 ° 38 ' E, 30 September 1994, Aust. water quality centre 3715 (1 SAMA); Mosquito Ck upstrm Struan, creek, 37 ° 6 ' S, 140 ° 47 ' E, 22 February 1994, Aust. water quality centre 3020 (1 SAMA); Mt Barker Ck upstrm Mt Barker Sprgs, creek, 35 ° 5 ' S, 138 ° 55 ' E, 12 May 1994, Aust. water quality centre 1875 (1 SAMA); Murray Bridge [no date], 35 ° 7 ' S, 139 ° 16 ' E, H. M. Hale (4 SAMA); Murray River [no date], 34 ° 57 ' S, 139 ° 16 ' E, A. H. Elston (4 AMSA Sydney); same locality, 34 ° 57 ' S, 139 ° 16 ' E, not given (1 SAMA); Murray River, shore washing, 34 ° 57 ' S, 139 ° 16 ' E, 27 November 1982, Endrödy­Younga (AU­ 13) (15 TMSA); North Para R. Rowland Flat, 34 ° 34 ' S, 139 ° 55 ' E, 11 October 1994, Aust. water quality centre 3443 (1 SAMA); Onkaparinga R. Hahndorf Bridge, 35 ° 1 ' S, 138 ° 47 ' E, 26 October 1994, Aust. water quality centre 3267 (1 SAMA); Pt. Lincoln, 34 ° 43 ' S, 135 ° 50 ' E, 1 – 30 January 1982, C. Watts (6 SAMA); The Deep Ck Dog Trap Ck, creek, 35 ° 36 ' S, 138 ° 12 ' E, 15 June 1994, Aust. water quality centre 3502 (1 SAMA); Tod R., White Flat, 34 ° 31 ' S, 135 ° 50 ' E, 10 November 1994, Aust. water quality centre 3683 (6 SAMA); Williamstown, 34 ° 40 ' S, 138 ° 53 ' E, 1 – 30 October 1961, C. Watts (2 SAMA); Tasmania: Coal River, 2.5 km E of Campania, mud and litter at edge of small river in pasture, elev. 45 m, 42 ° 40 ' S, 147 ° 28 ' E, 14 February 2000, N. Porch (42) (21 ANIC); Little Piper River at bridge on B 82, sandy litter at edge of river in scrubby forest, elev. 15 m, 41 ° 2 ' S, 147 ° 14 ' E, 12 February 2000, N. Porch (3) (53 ANIC); Nile River, 5 km NE of Deddington, cobble­bank of small river; remnant sclerophyll forest, pasture, elev. 275 m, 41 ° 34 ' S, 147 ° 28 ' E, 17 February 2000, N. Porch (72) (1 ANIC); [no other locality data; no date], A. M. Lea (1 MVMA); Orielton Rut u / s of Orielton Lagoon, 3.5 km NNW of Sorell, mud at edge of brackish? Estuary, elev. 2 m, 42 ° 45 ' S, 147 ° 32 ' E, 14 February 2000, N. Porch (37) (54 ANIC); Pipers Brook at B 82 bridge, 2.7 km NW of Pipers Brook, muddy litter at edge of small pools of perennial creek, elev. 50 m, 41 ° 3 ' S, 147 ° 10 ' E, 12 February 2000, N. Porch (17) (3 ANIC); Victoria: Avoca River at Avoca, litter and gravelly sand at edge of small river; pasture, elev. 225 m, 37 ° 5 ' S, 143 ° 28 ' E, 12 March 2000, N. Porch (71) (42 ANIC); Base of Trentham Falls, 2.3 km N Trentham, amongst wet gravel at edge of waterfall splash pool and outlet. Dry sclerophyll forest, elev. 640 m, 37 ° 22 ' S, 144 ° 19 ' E, 31 January 1999, N. Porch (NP 23) (1 ANIC); Coliban River, 5 km W of Redesdale, gravel at edge of small river flowing through pasture, elev. 280 m, 37 ° 0 ' S, 144 ° 28 ' E, 28 November 1999, N. Porch & N. Krause (8) (4 ANIC); Dandenong Creek at Brady Road, Dandenong North, mud at edge of artificial dam in pasture, elev. 30 m, 37 ° 57 ' S, 145 ° 13 ' E, 28 September 1999, N. Porch (53) (10 ANIC); Diamond Ck., 1.8 km NNE Tonimbuk, on fine­medium sand and amongst litter on sandbar in small creek flowing through dry sclerophyll forest, elev. 110 m, 37 ° 59 ' S, 145 ° 42 ' E, 4 February 1999, N. Porch (NP 25) (19 ANIC); Eel Hole Ck. on Nadenbouschs Rd. S 44 LaTrobe C. Survey, creek, 38 ° 18 ' S, 146 ° 23 ' E, 8 December 1978, not given (3 MVMA); same locality, 38 ° 18 ' S, 146 ° 23 ' E, 9 December 1978, not given (2 MVMA); Fryans Ck, 15 K S Stawell, creek, 37 ° 3 ' S, 142 ° 46 ' E, 13 January 1997, C. Watts (2 SAMA); Hopkins River at Western Highway, ex silty mud in shade under bridge at edge of pool. Pasture, but stream relatively natural, elev. 310 m, 37 ° 19 ' S, 143 ° 1 ' E, 3 March 1999, N. Porch (NP 40) (95 ANIC); Kororoit Creek, at Sydenham­Melton Road, organic mud and litter at edge of pool in dry creek in pasture and degraded riverine forest, elev. 110 m, 37 ° 41 ' S, 144 ° 38 ' E, 17 February 2002, N. Porch (91) (108 ANIC); Lerderderg River, 6.8 km N Bacchus Marsh, wet gravel and cobbles at edge of small river; dry sclerophyll forest, elev. 135 m, 37 ° 37 ' S, 144 ° 25 ' E, 20 September 1999, N. Porch (64) (5 ANIC); Little River at Bacchus Marsh­Geelong Road, sandy gravel and muddy sand at edge of still pool of perennial creek in riparian forest remnants, elev. 105 m, 37 ° 50 ' S, 144 ° 23 ' E, 20 October 1999, N. Porch (36) (169 ANIC); Loddon River at Guildford, sand and sandy mud at edge of small stream in pastureland, elev. 235 m, 37 ° 9 ' S, 144 ° 9 ' E, 17 February 2002, N. Porch (86) (8 ANIC); Loddon River at Newstead, gravel at edge of small river flowing through pasture, elev. 210 m, 37 ° 6 ' S, 144 ° 3 ' E, 27 November 1999, N. Porch (47) (4 ANIC); Melbourne [no date], 37 ° 58 ' S, 144 ° 58 ' E, (1 MVMA); Moorabool River East Branch, 2.0 km SE Ballark, gravel at edge of small river flowing through pasture, elev. 310 m, 37 ° 44 ' S, 144 ° 7 ' E, 20 October 1999, N. Porch (58) (20 ANIC); Morwell River on Driffield ­ Yinnar Rd., S 43, LaTrobe C. Survey, 38 ° 19 ' S, 146 ° 19 ' E, 6 December 1978 (1 MVMA); Mt Emu Ck., on Vite Vite Rd., 2 km S Pura Pura, on / in sandy mud at edge of slow flowing stream in pasture, elev. 185 m, 37 ° 50 ' S, 143 ° 6 ' E, 4 March 1999, N. Porch (NP 47) (40 ANIC); Tarago River, Bellbird Park at old Princes Highway, ex sandy mud and litter in sun along edge of slow flowing river in pasture, elev. 50 m, 38 ° 5 ' S, 145 ° 48 ' E, 15 January 1999, N. Porch (NP 21) (50 ANIC); Toomuc Ck., at Princes Highway, Pakenham, on silty sand and sand along margins of gravelly ' semi­urban' creek, elev. 45 m, 38 ° 4 ' S, 145 ° 28 ' E, 4 February 1999, N. Porch (NP 26) (7 ANIC); Werribee River in Werribee Gorge, gravel at base of gravel bank of small creek; dry sclerophyll forest, elev. 145 m, 37 ° 39 ' S, 144 ° 21 ' E, 20 September 1999, N. Porch (51) (20 ANIC); Wimmera River at Western Highway, muddy sand at edge of river pool in dry sclerophyll / riverine forest, elev. 100 m, 36 ° 25 ' S, 141 ° 58 ' E, 1 March 2000, N. Porch (61) (232 ANIC). Representative specimens to be deposited in CMNH, FMNH, MCZ, NPC, QMBA, and USNM.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE3FFD6FEC77A0A6F54F696.taxon	materials_examined	Type Material. Holotype (male): Papua New Guinea: Morobe District, c. 7 miles Lae ­ Bulolo Road, ex. gravel and grass roots on bank of small stream, 30 December 1964, M. E. Bacchus (MEB 120). Deposited in the BMNH. Paratypes (45): Papua New Guinea: Morobe District: Same data as holotype (36 BMNH); Markham Valley, Gusap, 90 mi. N. W. of Lae, ex. dead leaves on mud wetted by seepage, elev. 304 m, 27 – 30 January 1965, M. E. Bacchus (MEB 163) (2 BMNH); Markham Valley, Gusap, c. 90 mi. N. W. of Lae, large pond, muddy bottom with thick layer of dead leaves, dense Ceratophyllum, elev. 304.8 m, 27 – 30 January 1965, M. E. Bacchus (MEB 162) (7 BMNH). Representative specimens to be deposited in ANIC, CMNH, FMNH, MCZ, MVMA, NMW, NPC, QMBA, QPIM, SAMA, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE3FFD6FEC77A0A6F54F696.taxon	diagnosis	Differential Diagnosis. Recognized by the very convex form, the moderately shining dorsum, the finely sparsely punctate pronotum, and especially the confluent pronotal anterior and posterior foveae, forming a narrow sinuate line on each side of the median groove. Distinguished from G. trilineatus, which also has confluent pronotal foveae, by the more transverse and less convex pronotum, the non­striate­impressed elytral punctures, the longer setae of the elytral punctures, and the lack of a fringe of setae on the elytral lateral margins (Figs. 29, 33). The male genitalia of the two species show some similarity, both lacking barbs, but in G. bacchusi the lobes are longer and shaped differently, the duct is more elongate, and the parameres and paramere setae differ in form (Figs. 30, 34).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE3FFD6FEC77A0A6F54F696.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.57 / 0.69; head 0.27 / 0.42; pronotum 0.37 / 0.57; elytra 0.90 / 0.69. Form moderately ovate, elytra strongly convex. Color brown, head darker, dorsal reliefs shining. Frons very finely sparsely punctate, setae obsolete; interocular foveae moderately deep; interocular tuberculi distinct; basal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate; setae very sparse on disc, distinctly denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 3 x length; anterior margin arcuate, with very small apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate in midregion; lateral depression wide, each with posterior angle acute point, lateral margin weakly arcuate, with short fringe of setae; lateral fossulae deep, lacking microsculpture; pronotal disc transversely moderately convex, finely sparsely punctate, most punctures with a minute recumbent seta; median groove deep, narrow, extending nearly to margins, tapering at ends; anterior and posterior foveae slightly narrower than median groove, joined by narrow channel to form slightly sinuate groove; posterolateral angles without impressions. Elytra very convex on disc, with six rows of moderately sized punctures between suture and humeri, very weakly striate­impressed if at all; punctures with a short decumbent seta; intervals weakly rounded, if at all, width equal that of punctures; summit of declivity near midlength, where elytra are transversely markedly convex; sutural margin raised over posterior declivity; explanate margin narrow, setae recumbent, not forming fringe. Metasternal glabrous area slightly wider than long, oval, dull, nitid, convex. Abdominal ventrites 1 – 3 and anteriorly 4 with hydrofuge pubescence. Aedeagus (Fig. 34): Length of main­piece 0.28 mm, length to tip of parameres 0.31 mm; lobes very long and slender, in ventral aspect each very weakly produced apically on lateral margin, not barbed; parameres slightly widened on medial surface, apical seta elongate, ca. 2.5 x length of next longest. Females have the elytral margin similar to males, but lack the apicomedian process of the labrum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE3FFD6FEC77A0A6F54F696.taxon	etymology	Etymology. Named in honor of the collector, Mick Bacchus. Distribution. Currently known from Papua New Guinea. Notes. The microhabitat data can be viewed with a high level of confidence as reflecting the actual preferences of this species, since Mick Bacchus also collected ca. 3,097 Hydraena from streams in Papua New Guinea (Perkins, in prep.).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE8FFD9FEC779E86A68F5AE.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: Warburton R., 1 km N White Bull Yard Kalamurina Stn., 27 ° 52 ' S, 137 ° 54 ' E, 6 October 1999, WHC exped. Deposited in the SAMA. Paratypes (30): Australia: South Australia: Salt Ck at Mangalo, 33 ° 32 ' S, 136 ° 37 ' E, 10 November 1994, Aust. water quality centre 3686 (5 SAMA); Stoney Crossing, 8 km SW Kalamurina HS, Warburton River, 27 ° 46 ' S, 138 ° 12 ' E, 7 October 1999, WHC exped. (1 SAMA); Warburton R., 1 km N White Bull Yard Kalamurina Stn., 27 ° 52 ' S, 137 ° 54 ' E, 6 October 1999, WHC exped. (20 SAMA); Willochra Ck., 2 km E “ Proby’s Grave ”, 34 ° 4 ' S, 138 ° 6 ' E, 8 May 1981, J. A. Forrest (4 SAMA). Representative specimens to be deposited in ANIC, MCZ, NMW, NPC, and QMBA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE8FFD9FEC779E86A68F5AE.taxon	diagnosis	Differential Diagnosis. Recognized by elongate body form and elongate legs, the comparatively large elytra, the large and deep pronotal foveae, the shining dorsal reliefs, the deeply striate­impressed elytral series, and the equally wide and convex elytral intervals. Distinguished from G. coruscus and G. weiri by the very uniform height of the elytral intervals, the darker body coloration, and subtle differences in body proportions (Figs. 42, 44, 46). The male genitalia are most similar to that of G. sexplanatus, but differ in shape of the main­piece and paramere setae (Figs. 43, 49).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE8FFD9FEC779E86A68F5AE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 2.00 / 0.82; head 0.37 / 0.46; pronotum 0.44 / 0.59; elytra 1.30 / 0.82. Form moderately ovate, moderately convex. Dorsum brown to dark brown, head dark brown to black; dorsal reliefs strongly shining. Head dorsally finely sparsely punctate, weakly pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum length 0.5 width, anterior margin strongly arcuate; apicomedian tooth very low, behind which is oval depression. Maxillary palpomere 3 slightly greater than twice length of 4. Pronotum lateral hyaline border well developed, origin at base of lateral depression, margin straight then markedly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression wide, posterior angle produced to acute point, lateral margin arcuate, with very short fringe of setae; lateral fossulae deep, non­microreticulate; pronotal disc weakly convex, finely sparsely punctate, each puncture with a very small recumbent seta; median groove wide and deep, markedly constricted slightly behind midlength, extending nearly to margins, tapering at ends; anterior foveae oval, deep and large, wider than widest part of median groove; posterior foveae oblique, deep, slightly more than 1 / 2 as long as and as wide as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, with six rows of punctures in deep striae between suture and humeri; punctures round, usually separated from each other by less than puncture width; intervals high, rounded, very uniform, width slightly greater than that of punctures; summit of declivity near apical 0.66; striae 2 and 3 terminating into 4 at about apical 1 / 4; intervals 4 and 6 continuing in raised condition to apices; sutural margin slightly raised; elytral explanate margin moderately developed, without fringe of setae. Metasternal glabrous area longer than wide (as 16: 12), oval, shining, convex. Abdominal ventrites 1 – 3 and basal part of 4 with hydrofuge pubescence. Aedeagus (Fig. 43): Length of main­piece 0.38 mm, length to tip of parameres 0.43 mm; lobes relatively long, strongly barbed; dorsal notch U­shaped, wider than V­shaped ventral notch; apical paramere seta elongate, subapical seta ca. 0.5 x as long. Females have the explanate elytral margin about twice as wide as it is in males, about equal to the width of the mesotibia; the elytral sutural margins are sometimes weakly emarginate just before the apices, forming a narrow gap between the elytra; the labrum is simple, lacking the apicomedian tooth found in males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE8FFD9FEC779E86A68F5AE.taxon	etymology	Etymology. Named in reference to the markedly sculptured pronotum and elytra.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE8FFD9FEC779E86A68F5AE.taxon	distribution	Distribution. Currently known from central and south­central South Australia (Fig. 91).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE5FFD7FEC77D6A6971F1EE.taxon	materials_examined	Type Material. Holotype (by monotypy; female): Australia: Queensland: Brisbane, Kedron Pk., [labels: " TYPE [red disc] "; " ” 6373 ” Qu. [red] T. "; " Kedron Pk., Brisbane. C. Wild, 1892 "; " Blackburn coll. 1910 ­ 236 "; " Ochthebius brisbanensis, Blackb. "]. Deposited in the BMNH.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE5FFD7FEC77D6A6971F1EE.taxon	diagnosis	Differential Diagnosis. Recognized by the dull, matte dorsum, the abdominal ventrites 1 – 3 and minutely anteriorly 4 with hydrofuge pubescence, and the arcuate labrum in both sexes. Distinguished from G. levis, which also has a dull, pruinose dorsum, by the larger size, the more convex form, the more extensive hydrofuge pubescence, the lack of an apicomedian process of the labrum in males, and the male genitalia. Distinguished from G. fumosus by the finely sparsely punctate pronotal reliefs, the smaller elytral serial punctures, and the shining metasternal glabrous area. The male genitalia show some resemblance to that of G. fumosus, but in G. brisbanensis the lobes are shorter and more strongly barbed, the duct markedly arcuate, and the parameres extend further beyond the main­piece (Figs. 36, 38).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE5FFD7FEC77D6A6971F1EE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices): 1.73 / 0.73; head 0.31 / 0.44; pronotum 0.41 / 0.64; elytra 1.07 / 0.73. Form moderately ovate, moderately convex. Color dark brown, entire dorsal surface dull. Frons very finely sparsely punctate, nearly impunctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial depression with very weak midlongitudinal carina, depression anteriorly narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 x apical width, very sparsely punctate; pubescence very sparse on disc, slightly denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length, anterior margin arcuate. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression with posterior angle produced as acute point, lateral margin arcuate, with distinct fringe of short arcuate setae; lateral fossulae deep, microsculpture similar to remainder of pronotum; pronotal disc moderately convex, extremely finely sparsely punctate, setae very small and fine, if perceptible; median groove shallow, very narrow, extending nearly to margins, tapering at ends; anterior foveae small, pit­like at bottom of depression; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and subequal width of median groove; posterolateral angles each with shallow impression. Elytra moderately convex on disc, with six rows of small punctures between suture and humeri; punctures round, separated from each other by about puncture width, each with very fine seta; intervals rounded, width twice that of punctures; sutural interval raised; summit of declivity slightly behind midlength; striae 2 and 3 terminating into 4 at about apical 0.2; elytral margin lacking prominent setae. Prosternum with weak midlongitudinal carina. Metasternal glabrous area large, shining, convex, oval, slightly longer than wide (as 6: 5). Abdominal ventrites 1 – 3 and minutely anteriorly 4 with hydrofuge pubescence. Aedeagus (Fig. 36): Length of main­piece 0.27 mm, length to tip of parameres 0.29 mm; lobes relatively long, strongly barbed; notches U­shaped, ventral notch slightly narrowed apically, dorsal notch slightly wider than ventral notch; duct markedly arcuate at base of notches, then gradually enlarged to rounded apex; apical paramere seta elongate and sinuate, ca. 2 – 3 x length of next longest seta. Females have the explanate elytral margin and the labrum similar to that of males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE5FFD7FEC77D6A6971F1EE.taxon	distribution	Distribution. A rarely collected species, currently known from Brisbane south to southwestern Victoria (Fig. 79). Notes. Specimens from Victoria generally have the elytral setae slightly more apparent than specimens from more northern localities. The single male from Grampians National Park is smaller than usual, and the male genitalia differ very slightly from other specimens.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE5FFD7FEC77D6A6971F1EE.taxon	materials_examined	Material Examined (43): Australia: New South Wales: Cattai Creek NW of Sydney, creek, 33 ° 42 ' S, 150 ° 59 ' E, 12 December 1988, V. Lorimer (1 AMSA); [no other data], 1 January – 30 December 1858, Griffith (24 SAMA); Sydney [no date], 33 ° 52 ' S, 151 ° 12 ' E, Lea (2 SAMA); Tamworth [no date], 31 ° 5 ' S, 150 ° 55 ' E, Lea (3 SAMA); Victoria: 10 km NE Mirranatwa, small creek bed ­ drying pool, stony, dead leaves, dry sclerophyll forest, 37 ° 36 ' S, 142 ° 13 ' E, 12 October 1997, C. Watts (8 SAMA); Burrong Falls, 6.0 km W Mt. Victory, Grampians N. P., ex. margins of vertical and horizontal rockfaces (sandstone) of waterfalls. Dry sclerophyll forest, elev. 280 m, 37 ° 9 ' S, 142 ° 23 ' E, 2 March 1999, N. Porch (NP 42) (1 ANIC); Cann River, flood debris, 37 ° 29 ' S, 149 ° 9 ' E, 20 – 25 May 1978, S. & J. Peck (3 ANIC). Representative specimens to be deposited in MCZ, NPC, and QMBA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF0FFC6FEC77EEF6A3BF47E.taxon	description	(Figures 13, 14, 77)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF0FFC6FEC77EEF6A3BF47E.taxon	materials_examined	Type Material. Holotype of Ochthebius clarki (female): Australia: New South Wales: Sydney; [labels: " Sydney H. W. Cox "; " 3659 3660 Type "; " Ochthebius clarki Deane. "]. Deposited in the MVMA. Holotype of Ochthebius angustipennis (male): Australia: New South Wales: Sydney. Deposited in the MVMA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF0FFC6FEC77EEF6A3BF47E.taxon	diagnosis	Differential Diagnosis. Recognized by the dark brown to black head and pronotum with faint metallic reflections, the gradually sloping pronotal foveae which are moderately coarsely punctate like reliefs, the elytral series and intervals of about equal width, and the abdominal hydrofuge pubescence present on ventrites 1 – 2 entirely and 3 – 4 partially, with the hair­line medially on the anterior part of the 3 rd, weakly sinuate from there to anterolateral extreme of the 4 th. Readily distinguished from G. hesperius (which see) by color, body form, and male genitalia (Figs. 14, 20).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF0FFC6FEC77EEF6A3BF47E.taxon	description	Description. Size (length / width, mm) of the holotype of G. clarki: body (length to elytral apices) 1.57 / 0.74; head 0.28 / 0.42; pronotum 0.40 / 0.52; elytra 1.06 / 0.74. Dorsum shining, head and pronotum dark brown to black with faint metallic reflections, elytra dark brown, legs brown. Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae shallow; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, arcuate to weakly bisinuate. Clypeus midlength: apical width 1: 2, very finely sparsely punctate; pubescence very sparse on weakly raised disc, slightly denser laterally; anterior margin straight in dorsal aspect, evenly arcuate in frontal aspect. Labrum length: width 1: 2. Pronotum lateral hyaline border well developed, origin at base of lateral depression, markedly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum straight or weakly arcuate in midregion; each lateral depression with posterior in form of obtuse, almost right angle, lateral margin weakly arcuate anteriorly, weakly emarginate before posterior angle, with fringe of short setae; lateral fossulae moderately deep, effacedly if at all microreticulate; pronotal disc weakly convex, reliefs highly shining, sparsely, moderately coarsely punctate, punctures intermediate in size between those of head and elytra; each puncture on reliefs with an extremely small decumbent seta; median groove narrow, moderately shallow, slightly widened just before ends, then tapering, nearly attaining margins in most specimens; anterior and posterior foveae moderately deep, punctate like reliefs, margins gradually sloping, very ill­defined; posterolateral angles each with indistinct shallow impression. Elytra weakly convex on disc, with six rows of closely spaced, small punctures between suture and humeri; intervals weakly rounded, as wide as punctures; posterior declivity very gradual, summit slightly past midlength; striae 2 and 3 terminating into 4 at about apical 1 / 4; elytral margin lacking prominent setae; explanate margin narrow, slightly wider in female than male, terminating near posterior 3 / 4. Metasternal glabrous area length about equal width, widest before midlength, rhomboidal, shining, with a few setiferous punctures on disc. Abdominal ventrites 1 – 2 entirely and 3 – 4 partially hydrofuge pubescent; hairline medially on anterior part of 3 rd, weakly sinuate from there to anterolateral extreme of 4 th; cuticle strongly shining posterior to hairline. Aedeagus (Fig. 14): Length of main­piece 0.25 mm, length to tip of parameres 0.26 mm; lobes relatively short, not barbed; notches U­shaped, ventral notch widest apically, dorsal notch deeper and slightly wider ventral notch; duct weakly arcuate, width subequal that of lobe, tip truncate, simple; apical paramere seta elongate, ca. 2 – 3 x length of next longest seta.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF0FFC6FEC77EEF6A3BF47E.taxon	distribution	Distribution. A widely distributed species, known from Australia and Papua New Guinea. In Australia found from Victoria northward to northern Queensland and then west to northern Northern Territory (Fig. 77).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF0FFC6FEC77EEF6A3BF47E.taxon	materials_examined	Material Examined (298): Australia: New South Wales: Beaury Creek, adjacent Woodenbong State Forest, ca. 8 km [beeline] SW Woodenbong, ca. 120 km [beeline] SW Brisbane, 28 ° 24 ’ 09.9 ” S 152 ° 32 ’ 18.0 ” E, Residual pools and small rock pools in river bed (Beaury Creek), in cultivated cattle country, 25 August 2004, M. A. Jäch (AU 14) (2 NMW); Nyngan, 31 ° 33 ' S, 147 ° 12 ' E, 16 March 1963, C. Watts (4 SAMA); Parramatta, 33 ° 48 ' S, 151 ° 0 ' E, 26 March 1965, M. E. Bacchus (MEB 216) (2 BMNH); Shaw Creek, c. 8 m., Springwood­Richmond Rd., 33 ° 38 ' S, 150 ° 38 ' E, 24 March 1965, M. E. Bacchus (MEB 214) (1 BMNH); Northern Territory: 10 mi. E of Daly River, at light, 13 ° 45 ' S, 130 ° 51 ' E, 28 June 1972, B. K. Head (7 SAMA); 16 km E by N of Mt Cahill, 12 ° 51 ' S, 132 ° 42 ' E, 13 June 1973, Upton & Feehan (8 ANIC); 22 km WSW of Borroloola, 16 ° 8 ' S, 136 ° 6 ' E, 2 November 1975, M. S. Upton (10 ANIC); 7 km NW by N of Cahills Crossing, East Alligator River, 12 ° 23 ' S, 132 ° 56 ' E, 27 May 1973, E. G. Matthews (13 ANIC); 9 km N by E of Mudginbarry, 12 ° 31 ' S, 132 ° 54 ' E, 26 May 1973, E. G. Matthews (7 ANIC); same locality, 12 ° 31 ' S, 132 ° 54 ' E, 10 June 1973, Upton & Feehan (1 ANIC); Adelaide River, at Daly River road crossing, 13 ° 29 ' S, 131 ° 6 ' E, 9 November 1972, E. B. Britton (9 ANIC); Canon Hill Kakadu, 12 ° 16 ' S, 132 ° 40 ' E, 10 October 1998, C. Watts (1 SAMA); Daly R. Mission, 13 ° 18 ' S, 130 ° 15 ' E, 17 August 1974, J. Hutchinson (11 ANIC); Humpty Doo (6 km E), at UV light, 12 ° 37 ' S, 131 ° 15 ' E, 6 – 19 October 1990, R. I. Storey (5 QPIM); Ja Ja Billabong, 6 km NbyE Mudginberri, Berlesate, open forest litter, 12 ° 33 ', 132 ° 52 ' E, 27 November 1992, M. Storrs (22 ANIC); Jim Jim Creek, 19 km WSW of Mt. Cahill, 12 ° 57 ' S, 132 ° 33 ' E, 24 October 1972, E. B. Britton (26 ANIC); same locality, 12 ° 58 ' S, 132 ° 35 ' E, 17 July 1973, Upton & Feehan (1 ANIC); Koongarra, 15 km E of Mt Cahill, 12 ° 52 ' S, 132 ° 50 ' E, 12 June 1973, Upton & Feehan (9 ANIC); Nourlangie Creek, 8 km. E of Mt. Cahill, at light, 12 ° 52 ' S, 132 ° 47 ' E, 27 October 1972, E. B. Britton (1 ANIC); Nourlangie Creek, 8 km. N of Mt. Cahill, at light, 12 ° 48 ' S, 132 ° 42 ' E, 26 October 1972, E. B. Britton (1 ANIC); Red Lily Lagoon nr. Daly River, lagoon, 13 ° 45 ' S, 130 ° 42 ' E, 9 August 1980, M. B. Malipatil (12 MAGD); Yellow Water swamp nr Cooinda, swamp, 12 ° 16 ' S, 132 ° 40 ' E, 18 November 1979, M. B. Malipatil (5 MAGD); Queensland: 11 km WSW of Petford, at light, 17 ° 26 ' S, 144 ° 54 ' E, 3 – 4 April 1988, R. I. Storey (5 QPIM); 31 km NW by N of Longreach, 23 ° 13 ' S, 144 ° 4 ' E, 10 May 1973, M. S. Upton (2 ANIC); Biloela, 24 ° 24 ' S, 150 ° 30 ' E, 7 September 1972, H. E. Hinton (6 BMNH); Boggomoss No. 21, via Taroom, aquatic collection, 073, 25 ° 27 ' S, 150 ° 3 ' E, 11 November 1996, Thompson & Monteith (3 ANIC); Brisbane, 27 ° 22 ' S, 152 ° 46 ' E, 27 June 1927, not given (4 UQIC); Brookfield, 27 ° 29 ' S, 152 ° 53 ' E, 22 January 1982, J. Sedlacek (1 NMW); Bruce Hwy. nr Childers, 10 km N Howard, creeks, 25 ° 14 ' S, 152 ° 16 ' E, 17 November 1996, L. Hendrich (15 NMW); Bushland Beach, 12 km N Townsville, 19 ° 12 ' S, 146 ° 41 ' E, 15 – 20 March 1998, A. J. Watts (3 SAMA); Cape River, 100 km S Charters Towers, 21 ° 0 ' S, 146 ° 25 ' E, 12 December 2002, C. H. S. Watts (13 SAMA); Cape York, Archer River, Archer Bend, moderately large shallow billabong / pool in otherwise dry river bed; unvegetated with thick layer of dead leaves etc., 13 ° 28 ' S, 142 ° 12 ' E, 28 September 1983, C. Watts (1 BMNH); Carnarvon Ck. 17 km E Park Office, 25 ° 1 ' S, 148 ° 18 ' E, 14 August 2004, A. Glaister (4 NMW); Connor’s River, 91.5 mi. S Mackay, 22 ° 39 ' S, 149 ° 4 ' E, 3 September 1972, H. E. Hinton (2 BMNH); Gladstone [no date], 23 ° 52 ' S, 151 ° 16 ' E, Lea (6 SAMA); Hann R., 73 km NW by W of Laura, 14 ° 44 ' S, 144 ° 4 ' E, 27 June 1986, T. Weir & A. Calder (3 ANIC); Laura, moderate sized, shallow stoney river with little vegetation, 15 ° 34 ' S, 144 ° 27 ' E, 18 July 1982, C. Watts (2 SAMA); Leichart Creek, 8 k N Bluewater, 19 ° 10 ' S, 146 ° 32 ' E, 18 December 2002, A. J. & C. H. S. Watts (1 SAMA); Moggill, 27 ° 32 ' S, 152 ° 56 ' E, 4 March 1933, H. Hacker (1 ANIC); Moran's Creek, 760 – 820 m a. s. l., SW of O'Reilly's Rainforest Guesthouse, Lamington NP, ca. 80 km S Brisbane [beeline], 28 ° 14 ’ 11.2 ” S 153 ° 08 ’ 01.1 ” E – 28 ° 13 ’ 59 ” S 153 ° 07 ’ 27 ” E, River (Moran's Creek), ca. 2 – 4 m wide, through dense rain forest, Eucalypt forest and open grassland, 760 – 820 m a. s. l., 24 August 2004, M. A. Jäch (AU 9) (2 NMW); N. Pine R., Brisbane, 27 ° 17 ' S, 153 ° 4 ' E, 5 March 1932, P. J. Darlington (2 MCZ); North Maclean, on river bank, 27 ° 47 ' S, 153 ° 1 ' E, 13 October 1991, T. Gush (1 ANIC); South of Charleville, 26 ° 24 ' S, 146 ° 20 ' E, 9 May 1973, M. S. Upton (4 ANIC); Station Brdg 6 km SW Eidsvold, 25 ° 22 ' S, 151 ° 4 ' E, 15 August 2004, A. Glaister (3 NMW); Taroom Dist. Boggom. 1, 157, 25 ° 26 ' S, 150 ° 2 ' E, 8 June 1996, R. Kristensen (1 ANIC); Taroom Dist. Boggom. 11, 162, 25 ° 28 ' S, 150 ° 3 ' E, 14 June 1996, R. Kristensen (12 ANIC); Taroom Dist. Boggom. 2, 159, 25 ° 26 ' S, 150 ° 1 ' E, 8 June 1996, R. Kristensen (4 ANIC); Taroom Dist. Boggom. 5, 160, 25 ° 26 ' S, 150 ° 1 ' E, 14 June 1996, R. Kristensen (2 ANIC); Towns­ ville, 19 ° 15 ' S, 146 ° 48 ' E, 24 March 1932, P. J. Darlington (7 MCZ); same locality, elev. 10 m, 19 ° 15 ' S, 146 ° 48 ' E, 17 January 1993, Wewalka (1 NMW); Townsville [no date], 19 ° 15 ' S, 146 ° 48 ' E, G. F. Hill (1 MVMA); Victoria: Tarago R. at Elston Rd., 1.75 km W Neerim, ex silty sand patches between waterside vegetation and wet litter along edge of riffle. Dry sclerophyll forest­pasture, elev. 170 m, 38 ° 28 ' S, 145 ° 56 ' E, 15 January 1999, N. Porch (NP 20) (2 ANIC); Papua New Guinea: Central District, Loloki, 10 miles N of Port Moresby, ex. gravel in roadside drain, 19 March 1965, M. E. Bacchus (MEB 209) (2 BMNH); Moitaka, 7 miles N of Port Moresby, ex. dead leaves in gravelly shallow of small pond, 17 March 1965, M. E. Bacchus (MEB 207) (5 BMNH); Moitaka, 7 miles N of Port Moresby, very muddy gravel bank of field drain, 17 March 1965, M. E. Bacchus (MEB 204) (9 BMNH); Port Moresby ­ Brown River Road, ex. grassy shallows of large muddy pond, 15 March 1965, M. E. Bacchus (MEB 195) (9 BMNH). Representative specimens to be deposited in AMSA, CMNH, FMNH, MCZ, MVMA, NPC, QMBA, USNM, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEAFFDEFEC77C126AB7F27F.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: Warburton R., 1 km N White Bull Yard Kalamurina Stn., 27 ° 52 ' S, 137 ° 54 ' E, 6 October 1999, WHC exped. Deposited in the SAMA. Paratypes: Same data as holotype (7 SAMA). Representative specimens to be deposited in MCZ and NPC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEAFFDEFEC77C126AB7F27F.taxon	diagnosis	Differential Diagnosis. Recognized by the black head and bright testaceous pronotum and elytra, the elongate body form and legs, the large and deep pronotal foveae, the shining dorsal reliefs, and the deeply striate­impressed elytral series. Distinguished from G. benesculptus by the slightly more ovate body form, the less raised elytral intervals beyond the posterior declivity, and the lighter coloration (Figs. 42, 44). Distinguished from G. sexplanatus by the more strongly striate­impressed elytral series and relatively smaller pronotum (Fig. 48). The male genitalia distinctly differ from that of both compared species, being weakly barbed and with each paramere bearing a pair of thickened, elongate setae (Figs. 43, 45, 49).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEAFFDEFEC77C126AB7F27F.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 2.15 / 0.94; head 0.39 / 0.52; pronotum 0.48 / 0.69; elytra 1.41 / 0.94. Form moderately ovate. Head black, pronotum, elytra and appendages testaceous or light brown, dorsal reliefs shiny, non­microreticulate. Head shiny, frons finely sparsely punctate, sparsely pubescent; interocular foveae shallow; interocular tuberculi distinct; basomedial fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus parallel­sided, midlength: apical width 4: 7, finely, moderately densely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture weakly concave in dorsal view, evenly arcuate in anterior view. Labrum length: width 3: 7, anterior margin arcuate, with prominent apicomedian upturned tooth, behind which is oval depression. Pronotum lateral hyaline border well developed, origin at base of lateral depression, margin nearly straight, then markedly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly arcuate in midregion; each lateral depression wide, weakly arcuate from anterior angles, then emarginate before acute posterior angle, lateral margin with fringe of very short setae; lateral fossulae deep, surface irregular; pronotal disc weakly convex, reliefs shiny, finely sparsely punctate, each puncture with minute recumbent seta; median groove deep, narrow, constricted in midlength, extending nearly to margins, tapering at ends; anterior foveae oval, deep, 2 – 3 x greatest width of median groove; posterior foveae oval, oblique, deep, 0.5 as long as and 2 – 3 x as wide as median groove; posterolateral angles lacking impressions. Elytra moderately convex on disc, with six rows of punctures in deep striae between suture and humeri; punctures round, usually separated from each other by less than puncture width; intervals high, rounded, very uniform, width slightly greater than that of punctures; summit of declivity near apical 0.66; striae 2 and 3 terminating into 4 at about apical 1 / 4; intervals 4 and 6 not continuing in raised condition to apices; sutural margin not raised; elytral explanate margin moderately developed, without fringe of setae. Metasternal glabrous area longer than wide (as 17: 12), widest behind midlength, flat or weakly convex. Abdominal ventrites 1 – 3 and basally 4 with hydrofuge pubescence. Aedeagus (Fig. 45): Length of main­piece 0.39 mm, length to tip of parameres 0.45 mm; lobes relatively long, weakly barbed at apex; apical two paramere setae elongate, thickened, joined together, much longer than other setae. Females have the explanate elytral margin markedly arcuate, about twice as wide as it is in males, slightly wider than the mesotibia; the anterior margin of the labrum is arcuate, lacking the apicomedian tooth found in males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEAFFDEFEC77C126AB7F27F.taxon	etymology	Etymology. Named in reference to the gleaming dorsum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEAFFDEFEC77C126AB7F27F.taxon	distribution	Distribution. Currently known only from the type locality in north­central South Australia (Fig. 89).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF91FFA0FEC779AA6AB7F346.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: Elizabeth (Mound) Springs, 7 km NW Coward Springs R. S., 29 ° 24 ' S, 136 ° 47 ' E, 14 May 1981, J. A. Forrest. Deposited in the SAMA. Paratypes: Same data as holotype (11 SAMA). Representative specimens to be deposited in MCZ and NPC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF91FFA0FEC779AA6AB7F346.taxon	diagnosis	Differential Diagnosis. Recognized by the rather flattened and parallel­sided form, the subtruncate elytral apices, and the dull, microreticulate and coarsely densely punctate pronotum. Sharing with G. nigriceps the anteriorly extended lateral hyaline border, the distinctive abdominal hydrofuge pattern where the hair­line forms a very discrete arc on the fifth ventrite, and the females having a spinose last tergite. Differing from G. nigriceps in having the pronotal disc more coarsely punctate, the dorsum less convex and more parallel­sided (Figs. 50, 52), the coloration, and in females the angulate last tergite. The male genitalia of the two species also show a relationship, but differ significantly in several features, including lobe and duct shapes, and the greater length in G. fontinalis (Figs. 51, 53).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF91FFA0FEC779AA6AB7F346.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 2.04 / 0.82; head 0.33 / 0.48; pronotum 0.44 / 0.59; elytra 1.30 / 0.82. Form moderately elongate, comparatively longitudinally planar. Head and disc of pronotum piceous to dark brown, on pronotum grading to brown or light brown at margins; elytra light brown to testaceous. Dorsum dull, microreticulate and coarsely punctate. Head comparatively flat, dull, markedly microreticulate, with moderately dense, short distinctive whitish setae; interocular foveae shallow; interocular tuberculi indistinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum length: width 4: 15, anterior margin straight or slightly emarginate, weakly reflexed. Pronotum lateral hyaline border well developed, origin at anterior 0.33 of lateral depression, margin straight, then arcuate at posterior angles, very narrow around posterior margin; anterior margin of pronotum straight in midregion; each lateral depression with margin weakly arcuate from anterior angle, then emarginate before slightly obtuse posterior angle, lateral margin between anterior angle and hyaline border with short setae; lateral fossulae deep, microreticulate; pronotal disc transversely weakly convex; median groove rather shallow, narrow, constricted slightly past midlength, ended before margins, tapering at ends; anterior foveae deep, oblique, oval, wider than median groove, each separated from posterior fovea by width of anterior fovea; posterior foveae very slightly oblique, nearly parallel to median groove, deep, 1 / 2 as long as and twice as wide as median groove; posterolateral angles lacking impressions. Elytra weakly transversely convex on disc, with six rows of punctures between suture and humeri; punctures round, separated from each other by 0.5 – 1.0 x puncture width, each with a short recumbent seta; intervals flat or slightly rounded, moderately dull, width slightly greater than that of punctures; posterior declivity very gradual, summit at about midlength; striae 2 and 3 terminating into 4 at about apical 0.15; elytral explanate margin very narrow, without fringe of setae. Metasternal glabrous area longer than wide (as 20: 17), elongate oval, shining, sparsely punctate, convex in female, more nearly flat in male. Abdominal sternites 1 – 4 and part of 5 with hydrofuge pubescence; on 5 pubescence laterally and basally, forming very discrete arc­shaped non­pubescent area. Sixth ventrite posterior margin emarginate, in male strongly, in female weakly. Aedeagus (Fig. 53): Length of main­piece 0.64 mm, tips of parameres slightly below tips of lobes; main­piece markedly elongated and slender between base and origin of parameres; lobes short compared to total length of aedeagus, not barbed but sometimes with extremely minute point on inner margin of ventral notch; ventral notch V­shaped, wide apically, margins not sinuate; dorsal notch U­shaped, wider proximally and slightly deeper; duct straight and gradually tapering in ventral aspect, weakly curved apically in lateral aspect; paramere setae clustered at and near apex, apical setae short, longest seta ca. 3 x length of next longest. Females have the explanate elytral margin about the same width as in males; the labrum is apicomedially weakly emarginate; the last abdominal tergite is sharply arcuate and has a prominent fringe of spine­like setae.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF91FFA0FEC779AA6AB7F346.taxon	etymology	Etymology. Named in reference to the microhabitat.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF91FFA0FEC779AA6AB7F346.taxon	distribution	Distribution. Currently known only from Elizabeth (Mound) Springs in central South Australia (Fig. 90).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE7FFD5FEC77E426F96F566.taxon	materials_examined	Type Material. Holotype (male): Australia: New South Wales: Sydney, 33 ° 52 ' S, 151 ° 12 ' E, 1 – 30 May 1961, C. Watts. Deposited in the SAMA. Paratype: Same data as holotype (1 SAMA).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE7FFD5FEC77E426F96F566.taxon	diagnosis	Differential Diagnosis. Recognized by the dull, matte dorsum, the abdominal ventrites 1 – 3 and minutely anteriorly 4 with hydrofuge pubescence, and the dull metasternal glabrous area. The dorsum is much more strongly punctate, especially the elytral series, than that of G. brisbanensis and G. levis, each of which also have the dorsum dull, matte (Figs. 35, 37, 40). The male genitalia show some resemblance to that of G. brisbanensis, but in G. fumosus the lobes are longer and more weakly barbed, the duct weakly arcuate, and the parameres do not extend as far beyond the main­piece (Figs. 36, 38).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE7FFD5FEC77E426F96F566.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.49 / 0.67; head 0.30 / 0.42; pronotum 0.37 / 0.54; elytra 0.94 / 0.67. Form moderately ovate, moderately convex. Dorsum dark brown, effacedly microreticulate or matte, dull. Head with frons moderately finely punctate, setae small and very sparse; interocular foveae deep; interocular tuberculi distinct; basal midlongitudinal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 3 x length; anterior margin arcuate, without apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly arcuate in midregion; each lateral depression with posterior angle acute, lateral margin arcuate from anterior angle, then distinctly emarginate in front of posterior angle, with very short indistinct setae; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, finely moderately densely punctate, setae very small, indistinct; median groove moderately deep, narrow, extending nearly to margins, tapering at ends; anterior foveae well developed, slightly elongate; posterior foveae oblique, linear impressions 1 / 2 as long as and as wide as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, sides nearly vertical in basal 0.5, with six rows of deep, closely spaced punctures in shallow striae between suture and humeri; each puncture with short indistinct seta; intervals flat or slightly rounded, width 0.5 – 1.0 x that of punctures; elytral margin without fringe of setae; summit of declivity near slightly past midlength, where elytra are transversely markedly convex; explanate margin very narrow, without fringe of setae. Metasternal glabrous area length about equal width, dull. Abdominal ventrites 1 – 3 and basally minutely 4 with hydrofuge pubescence. Aedeagus (Fig. 38): Length of main­piece 0.26 mm, length to tip of parameres 0.27 mm; lobes relatively long, moderately strongly barbed; notches U­shaped, ventral notch nearly parallel­sided, dorsal notch slightly shallower than ventral notch; duct weakly arcuate just before rounded apex; several paramere setae broken on holotype. Females unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE7FFD5FEC77E426F96F566.taxon	etymology	Etymology. Named in reference to the dull, " smoky " dorsum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE7FFD5FEC77E426F96F566.taxon	distribution	Distribution. Currently known only from the type locality, Sydney (Fig. 85).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF6FFCAFEC77C126FFEF066.taxon	materials_examined	Type Material. Holotype (male): Australia: Western Australia: Lyndon R. Bridge, 23 ° 36 ' S, 113 ° 51 ' E, 13 August 1975, K. & E. Carnaby. Deposited in the ANIC. Paratypes (36): Australia: Western Australia: 10 km NW Eerala Stn., 21 ° 19 ' S, 117 ° 2 ' E, 23 May 2001, C. H. S. Watts (3 SAMA); Carine, Perth, grass pile, 31 ° 51 ' S, 115 ° 46 ' E, 1 – 30 May 1983, V. Lorimer (1 AMSA); L. Walyungup, 32 ° 20 ' S, 115 ° 46 ' E, 1 – 30 March 1972, P. Zwick (9 MCZ); Lyndon R. Bridge, 23 ° 36 ' S, 113 ° 51 ' E, 13 August 1975, K. & E. Carnaby (13 ANIC); Millstream, shallow stream, from gravel at edge of pool at pipe crossing, 21 ° 35 ' S, 117 ° 4 ' E, 2 November 1970, E. Britton (1 ANIC); Murchison R., 27 ° 49 ' S, 114 ° 41 ' E, 28 March 1971, E. F. Riek (2 ANIC); Wooramel River, Callytharra Springs Stn, 25 ° 49 ' S, 115 ° 22 ' E, 20 May 2001, C. H. S. Watts (3 SAMA); same locality, 25 ° 49 ' S, 115 ° 22 ' E, 26 May 2001, C. H. S. Watts (4 SAMA). Representative specimens to be deposited in MCZ, NMW, NPC, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF6FFCAFEC77C126FFEF066.taxon	diagnosis	Differential Diagnosis. Recognized by the relatively large eyes and large elytra, the black head contrasting with the primarily testaceous body, the pronotal disc with foveae large and microreticulate, contrasting with the finely sparsely punctate and shining reliefs, and the abdominal hydrofuge pubescence restricted to ventrites 1 – 2 and basolaterally on 3. This species is very readily distinguished from the somewhat similar G. clarki by the larger body size (ca. 1.70 mm vs. 1.57 mm), the smaller pronotum (in relation to the elytra), the much more finely sparsely punctate and shining pronotal reliefs and the with deeper and larger foveae, and the color differences. The male genitalia of the two species distinctly differ in several features; in G. hesperius the parameres are longer and wider, the lobes each have a barb near the apex, and the duct is enlarged apically (Figs. 14, 20).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF6FFCAFEC77C126FFEF066.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.70 / 0.73; head 0.33 / 0.44; pronotum 0.37 / 0.56; elytra 1.07 / 0.73. Form moderately ovate, mod­ erately convex. Elytra and legs testaceous, pronotum testaceous laterally, darker medially, head black. Head and pronotal reliefs highly shining, elytra less so. Head with eyes relatively large in dorsal aspect; frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep, effacedly microreticulate; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, arcuate. Clypeus midlength: apical width 3: 5, very finely sparsely punctate; pubescence very sparse on disc, slightly more developed laterally; anterior margin arcuate toward rear and edge upturned to form low ridge. Labrum length: width 2: 5, subtriangular in dorsal aspect, apicomedian tooth upturned. Pronotum lateral hyaline border well developed, origin at base of lateral depression, very weakly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate in midregion; each lateral depression with posterior in form of right angle, lateral margin arcuate, with fringe of short setae; lateral fossulae deep, microreticulate; pronotal disc moderately convex, reliefs highly shining, extremely finely sparsely punctate, fovea dull, microreticulate; each puncture on reliefs with an extremely small recumbent yellow seta; median groove moderately deep, constricted just behind midlength, forming narrow channel, extending nearly to margins, tapering at ends; anterior foveae well developed; posterior foveae oblique, oval impressions nearly 1 / 2 as long as and twice as wide as widest part of median groove; posterolateral angles each with distinct shallow impression. Elytra moderately wide, weakly convex on disc, with six rows of punctures between suture and humeri; serial punctures moderately coarse, closely spaced; intervals weakly rounded, as wide as punctures; summit of declivity near apical 1 / 4; striae 2 and 3 terminating into 4 at about apical 1 / 4; intervals 4 and 5 slightly swollen at posterior declivity; elytral margin lacking prominent setae; explanate margin narrow, present over middle 0.5. Metasternal glabrous area length about equal width, widest before midlength, suboval, shining, with a few punctures. Abdominal ventrites 1 – 2 and basolaterally 3 with hydrofuge pubescence. Aedeagus (Fig. 20): Length of main­piece 0.28 mm, length to tip of parameres 0.31 mm; main­piece widened near midlength in lateral aspect, widened at base of lobes in ventral aspect; lobes relatively long, tapering rather abruptly, each with a very small barb subapically on ventral surface; dorsal notch U­shaped, wider than V­shaped ventral notch which is slightly deeper and slightly narrowed apically; duct enlarged apically; parameres in ventral aspect widened on inner surface apically, in general wider in lateral aspect than in ventral aspect, apical seta elongate, ca. 2 x length of next longest seta. Females have the elytral explanate margin slightly wider than that of males; the anterior margin of the labrum is arcuate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF6FFCAFEC77C126FFEF066.taxon	etymology	Etymology. Named in reference to the western distribution.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF6FFCAFEC77C126FFEF066.taxon	distribution	Distribution. Currently known from western Western Australia (Fig. 73).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF98FFA8FEC77CC2694CF2A6.taxon	materials_examined	Type Material. Holotype (male): Australia: Western Australia: Millstream, creek nr. Deep Reach, 21 ° 35 ' S, 117 ° 4 ' E, 8 November 1970, E. B. Britton. Deposited in the ANIC. Paratypes (12): Australia: Northern Territory: Finke River at Glen Helen Gorge, West Macdonnells NP, flowing river, large pools, with bulrushes, sandy bottom, algal growth, 23 ° 41 ' S, 132 ° 40 ' E, 10 March 1995, T. Weir (1 ANIC); Hugh River, 12.5 km SSE of Paisley Bluff, flowing river, deep pool, grass at edges, sandy bottom, 23 ° 49 ' S, 133 ° 22 ' E, 7 March 1995, T. Weir (2 ANIC); Palm Valley, 24 ° 4 ' S, 132 ° 45 ' E, 1 – 30 April 1968, C. Watts (2 SAMA); Simpson Gap, West Macdonnells NP, large pools in flowing creek (temporary) with grass at edge, 20 ° 40 ' S, 133 ° 43 ' E, 6 March 1995, T. Weir (4 ANIC); Western Australia: Fortescue River 12 k S Newman, 23 ° 28 ' S, 119 ° 44 ' E, 27 May 2001, C. H. S. Watts (1 SAMA); Lyndon R. Bridge, 23 ° 36 ' S, 113 ° 51 ' E, 13 August 1975, K. & E. Carnaby (2 ANIC). Representative specimens to be deposited in MCZ and NPC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF98FFA8FEC77CC2694CF2A6.taxon	diagnosis	Differential Diagnosis. A very distinctive species (Fig. 62), separated from all others in the genus by the combination of the non­serial elytral punctation, each puncture with a short, slightly flattened and widened seta, the convex body form, the fringe of long setae on the elytral margin, and the abdominal hydrofuge covering ventrites 1 – 2 and basolaterally on 3. The male genitalia show some slight resemblance to those of G. squamifer and G. minipunctus, both of which are very different in habitus (Figs. 56, 66).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF98FFA8FEC77CC2694CF2A6.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.52 / 0.71; head 0.33 / 0.44; pronotum 0.37 / 0.59; elytra 0.96 / 0.71. Form moderately ovate, moderately convex. Color dark brown, dorsum weakly shining, with distinctive whitish or yel­ lowish setae. Head with dorsum clothed in distinctive decumbent setae; frons sparsely punctate; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength about 0.5 apical width, moderately coarsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width about three times length, anterior margin with very small apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate between lateral depressions; each lateral depression with posterior angle slightly acute, lateral margin weakly arcuate, densely clothed in setae which overlap one another; lateral fossulae deep, terminating anteriorly in pit; pronotal disc moderately convex, very effacedly microreticulate and moderately densely punctate, each puncture with a distinctive recumbent whitish seta which contrasts with dark cuticle; median groove moderately deep and wide, constricted in midlength, extending nearly to margins, tapering at ends; anterior foveae well developed; posterior foveae oblique, linear impressions 1 / 2 as long as and about as wide as median groove; posterolateral angles lacking impressions. Elytra quite convex on disc; punctures random on disc, becoming serial laterally and behind posterior declivity; each puncture microreticulate and with a distinctive short flat recumbent seta; summit of declivity slightly behind midlength; sutural margin slightly raised; elytral explanate margin narrow, with fringe of short arcuate setae. Metasternal glabrous area length equal width, oval, shining, convex. Abdominal sternites 1 – 2 and basolateral part of 3 with hydrofuge pubescence. Aedeagus (Fig. 63): Length of main­piece 0.23 mm, length to tip of parameres 0.24 mm; lobes of moderate length, barbed subapically; dorsal notch deeper and wider than ventral notch; paramere setae short. Females are similar to males in form of the elytral explanate margin; the anterior margin of the labrum is arcuate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF98FFA8FEC77CC2694CF2A6.taxon	etymology	Etymology. Named in reference to the non­serial elytral punctation.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF98FFA8FEC77CC2694CF2A6.taxon	distribution	Distribution. Currently known from western Western Australia and southern Northern Territory (Fig. 74).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE9FFDBFEC77CC26F9EF11E.taxon	materials_examined	Type Material. Holotype (female): Australia: Victoria: Echuca [labels: " Echuca. Vic 3.1. 32 F. E. Wilson "; " Type 2274 "]. Deposited in the MVMA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE9FFDBFEC77CC26F9EF11E.taxon	diagnosis	Differential Diagnosis. Recognized by the small size (ca. 1.40 mm), the entirely dull, pruinose dorsum, the elytral fringe of setae, the very small, slightly elongate elytral serial punctures, and the comparatively wide elytral intervals. Easily differentiated from G. brisbanensis, which is also pruinose dorsally, by the smaller size and the fringe of setae on the elytral lateral margins. The male genitalia of the two species are quite distinct (Figs. 36, 41).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE9FFDBFEC77CC26F9EF11E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.40 / 0.64; head 0.28 / 0.40; pronotum 0.36 / 0.56; elytra 0.96 / 0.64. Form moderately ovate, moderately convex. Color brown, head slightly darker. Pronotum and elytra dull, pruinose. Head with frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep, Y­shaped; interocular tuberculi well developed, transverse; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength twice apical width, shiny, very sparsely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length, anterior margin arcuate, with apicomedian small tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression a single lobe, upturned at anterior, excavate at posterior, and bordered laterally with decumbent setae; lateral fossulae deep, microsculpture similar to remainder of pronotum; pronotal disc moderately convex, extremely finely sparsely punctate, dull but without apparent microreticulation (pruinose); foveae with similar surfaces; median groove shallow, very narrow, extending nearly to margins, tapering at ends; anterior foveae shallow, small, closer to lateral fossulae than to median groove; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and similar in width to median groove; posterolateral angles with distinct shallow impressions. Elytra moderately convex on disc, dull similar to pronotum, with six rows of shallow punctures in very shallow striae between suture and humeri; intervals flat, width 4 x that of punctures, punctures longer than wide, separated serially from each other by about puncture length; summit of declivity near apical one­third; explanate margin narrow, with fringe of setae which extend out from margin about 3 x that of lateral setae of pronotum. Prosternum with midlongitudinal carina. Metasternal glabrous area large, shiny, length equal width, oval. Abdominal ventrites 1 – 2 and anterior margin of 3 with hydrofuge pubescence. Aedeagus (Fig. 41): Length of main­piece 0.23 mm, length to tip of parameres 0.26 mm; lobes relatively long and slender, barbed subapically and apically; ventral notch deeper than dorsal notch; duct widened apically; all paramere setae short. Females have the elytral explanate margin similar to that of males; the labrum has a minute apicomedian tooth.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE9FFDBFEC77CC26F9EF11E.taxon	distribution	Distribution. Currently known from Victoria (Fig. 83).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE9FFDBFEC77CC26F9EF11E.taxon	discussion	Remarks. Deane's figure 4 (1933: 23) is misleading with regard to the shape of the pronotum as the lateral hyaline borders are not drawn. Also, the pronotum is drawn at a deflexed angle which makes it appear more transverse.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE9FFDBFEC77CC26F9EF11E.taxon	materials_examined	Material Examined (12): Australia: Victoria: Settling Pods Dam, at Junction of Settling Ponds Tk. & Hudbrick Tk., gravelly mud at edge of small dam in dry sclerophyll forest, elev. 260 m, 37 ° 7 ' S, 143 ° 70 ' E, 9 June 2001, N. Porch (74) (3 ANIC); Woori Yallock Ck., at Warburton Highway, ex muddy margins of undercut creek banks near water level; pasture, elev. 110 m, 37 ° 47 ' S, 145 ° 31 ' E, 23 February 1999, N. Porch (NP 35) (1 ANIC); ' Yarra Flats', Eaglemont (Melbourne suburb), ex mud at edge of small drying ' billabong' in parklands, elev. 15 m, 37 ° 46 ' S, 145 ° 4 ' E, 26 February 1999, N. Porch (NP 37) (8 ANIC). Representative specimens to be deposited in MCZ, NPC, and SAMA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCAFFFDFEC779426A3BF5DE.taxon	description	(Figures 9, 10, 82)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCAFFFDFEC779426A3BF5DE.taxon	materials_examined	Type Material. Holotype of Ochthebius lividus (female): Australia: Victoria: Echuca, [labels: " Echuca. Vic 3.1. 32 F. E. Wilson "; " Type 2276 "]. Deposited in the SAMA. Holo­ type of Ochthebius flavocinctus (female): Australia: Victoria: Echuca. Deposited in the MVMA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCAFFFDFEC779426A3BF5DE.taxon	diagnosis	Differential Diagnosis. Recognized by the relatively large lateral hyaline border with its origin near the basal one­third of lateral depression, the elytral intervals twice as wide as the very weakly striate­impressed serial punctures, the non­punctate area between striae 1 and 4, resulting from shortened striae 2 and 3, the labroclypeal suture weakly bisinuate in dorsal view, and the faintly lead­like coloration of the head and pronotum. The two species which also have an anteriorly extended lateral hyaline border, G. fontinalis and G. nigriceps, differ markedly in body form, sculpture, color, and aedeagal structure (Figs. 9, 50, 52). G. lividus has some resemblance to G. notalis (which see).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCAFFFDFEC779426A3BF5DE.taxon	description	Description. Size (length / width, mm) of the holotype of G. lividus: body (length to elytral apices) 2.00 / 0.96; head 0.36 / 0.52; pronotum 0.68 / 0.72; elytra 1.36 / 0.96. Form moderately ovate, moderately convex. Color: head black, pronotum blackish brown, faintly bluish, on disc, grading to light brown laterally, elytra and legs brown. Frons shiny, very finely sparsely punctate, very sparsely pubescent; interocular foveae deep, L­shaped; interocular tuberculi moderately distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength / width 0.16 / 0.28, shiny, very sparsely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture weakly bisinuate in dorsal view, evenly arcuate in anterior view. Labrum width nearly three times length, moderately densely pubescent, anterior margin arcuate, apicomedially with distinct tooth in male, slightly upturned but not emarginate in female. Pronotum lateral hyaline border well developed, origin near basal one­third of lateral depression, in front of which margin is setose, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; lateral fossulae deep, microsculpture similar to remainder of pronotum; pronotal disc shiny, weakly convex, moderately densely punctate, most punctures separated by 2 – 3 times puncture diameter; median groove shallow, narrow, extending nearly to margins; anterior foveae shallow, densely punctate, slightly closer to lateral fossulae than to median groove; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and similar in width to median groove; posterolateral angles within indistinct shallow impressions. Elytral disc moderately convex, shiny similar to pronotum, with six rows of moderately large punctures in moderately impressed striae between suture and humeri; intervals rounded, width twice that of punctures, punctures round, separated from each other by less than puncture diameter; striae 1 (sutural) and 4 continuing to elytral apices, striae 2 and 3 ended at about apical 1 / 4, resulting in distinctive non­punctate area between striae 1 and 4; summit of declivity near apical one­third; explanate margin moderately wide, with sparse recumbent setae. Prosternum with very weak midlongitudinal carina. Metasternal glabrous area large, shiny, length equal width, suboval, with extremely faint indication of midlongitudinal impression. Abdominal ventrites 1 – 3 and lateral, anterior areas of 4 with hydrofuge pubescence; suture between ventrites 4 and 5 more apparent than sutures separating other ventrites. Aedeagus (Fig. 10): Length of main­piece 0.36 mm, length to tip of parameres 0.41 mm; lobes moderately long, narrow, not barbed; notches U­shaped, widest apically, nearly twice width of a lobe; duct as wide as lobe, straight and nearly parallel­sided except bent at apex; apical paramere seta elongate, ca. 2 x length of next longest seta. Females have the elytral explanate margin similar to that of males; the labrum is arcuate anteriorly, and lacks a tooth; the clypeal anterior margin is bisinuate, but more weakly so than that of males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCAFFFDFEC779426A3BF5DE.taxon	distribution	Distribution. Widely distributed in Victoria: and currently known from a few localities in New South Wales and the Australian Capital Territory (Fig. 82).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCAFFFDFEC779426A3BF5DE.taxon	discussion	Remarks. Deane's (1933: 23) figure of G. lividus is entirely misleading with regard to shape of the pronotum and its relief features: lateral and anterior hyaline borders are not indicated, and anterior foveae are omitted. His illustration for O. flavocinctus is even more incorrectly drawn as it lacks hyaline borders, median groove and anterior and posterior foveae; all of these features are clearly apparent on the type specimen.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCAFFFDFEC779426A3BF5DE.taxon	materials_examined	Material Examined (881): Australia: Australian Capital Territory: Black Mtn., light trap, 35 ° 16 ' S, 149 ° 6 ' E, 12 March 1968, M. S. Upton (3 ANIC); same locality, 35 ° 16 ' S, 149 ° 6 ' E, 27 March 1968, M. S. Upton (3 ANIC); Blundells Ck. 3 km E of Piccadilly Circus, flight intercept window / trough trap, elev. 850 m, 35 ° 22 ' S, 148 ° 50 ' E, 1 January – 30 March 1984, Weir, Lawrence, Johnson (1 ANIC); New South Wales: Albury [no date], 36 ° 3 ' S, 146 ° 54 ' E, not given (3 SAMA); Araluen Crk. Cmpgrnd ca. 35 km S Braidwood, at u­v light, 35 ° 39 ' S, 149 ° 49 ' E, 2 – 3 December 1990, Pollock & Reichert (1 NMW); Victoria: 12 km SE Merrijig, Howqua River, 37 ° 6 ' S, 146 ° 15 ' E, 30 November 1971, A. Neboiss (1 MVMA); 55 km N Cavendish, Glenelg R. at hwy 107, spring­fed billabong, Scirpus, bark, leaves at margin, 38 ° 3 ' S, 141 ° 0 ' E, 28 May 1996, R. E. Roughley (14 NMW); Billabong 3, Yarra Glen, 37 ° 39 ' S, 145 ° 22 ' E, 6 April 1976, A. Fletcher (6 SAMA); Bunyip R. at Princes Highway, amongst willow roots and on sand at edge of river under thick willow cover in pasture, elev. 40 m, 38 ° 5 ' S, 145 ° 45 ' E, 15 January 1999, N. Porch (NP 22) (1 ANIC); Eppalock Res., Redesdale, 37 ° 0 ' S, 144 ° 28 ' E, 27 November 1967, A. Neboiss (2 MVMA); Farm pond nr. Glenmaggie Res., 37 ° 54 ' S, 146 ° 46 ' E, 7 May 1977, not given (1 MVMA); Fryer’s Creek near mouth into Lake Eildon, 37 ° 11 ' S, 145 ° 53 ' E, 3 October 1972, P. Zwick (1 NMW); Goulbourn River, at Goulbourn Valley Hwy., 8.0 km SE Seymour, sandy mud at edge of large slow river, elev. 145 m, 37 ° 5 ' S, 145 ° 12 ' E, 11 August 1999, N. Porch (70) (15 ANIC); Holey Plains State Park, firedam on Crooke Track, fine sand and organics at the edge of a small firedam in dry sclerophyll forest, elev. 45 m, 38 ° 10 ' S, 146 ° 20 ' E, 16 April 2002, N. Porch (87) (1 ANIC); Jamieson River at Jamieson, river, 38 ° 35 ' S, 143 ° 53 ' E, 2 October 1972, P. Zwick (1 MCZ); Kiewa Valley Hwy. n. Redbank, 36 ° 56 ' S, 143 ° 19 ' E, 13 February 1998, L. Hendrich (10 NMW); Kororoit Creek, at Sydenham­Melton Road, organic mud and litter at edge of pool in dry creek in pasture and degraded riverine forest, elev. 110 m, 37 ° 41 ' S, 144 ° 38 ' E, 17 February 2002, N. Porch (91) (2 ANIC); Lake Glenmaggie at Glenmaggie bridge, sandy margins of large reservoir, elev. 75 m, 37 ° 53 ' S, 146 ° 44 ' E, 1 December 1999, N. Porch (NP 39) (38 ANIC); Latrobe Riv. above confluence with Thomson Riv., 38 ° 9 ' S, 146 ° 34 ' E, 9 December 1978, not given (14 MVMA); Latrobe Riv., Glengarry ­ Traralgon Rd., 38 ° 9 ' S, 146 ° 34 ' E, 9 December 1978, [collr. not given] (2 MVMA); Little River at Bacchus Marsh­Geelong Road, sandy gravel and muddy sand at edge of still pool of perrenial creek in riparian forest remnants, elev. 105 m, 37 ° 50 ' S, 144 ° 23 ' E, 20 October 1999, N. Porch (36) (3 ANIC); Loddon River at Newstead, gravel at edge of small river flowing through pasture, elev. 210 m, 37 ° 6 ' S, 144 ° 3 ' E, 27 November 1999, N. Porch (47) (66 ANIC); Macalister River 0.5 km below Glenmaggie weir, NMV Survey Dept. GRES Mc 22 no. 2, river, 37 ° 46 ' S, 146 ° 40 ' E, 4 December 1976, [collr. not given] (2 MVMA); Macalister­ Thomson River Jn, NMV Survey Dept. GRES T 26 no. 1, 37 ° 46 ' S, 146 ° 40 ' E, 5 December 1976, (4 MVMA); Macalister­Thomson River Jn, NMV Survey Dept. GRES T 26 no. 5, 37 ° 46 ' S, 146 ° 40 ' E, 7 May 1977, not given (1 MVMA); Macalister­Thomson River Jn, NMV Survey Dept. GRES T 26 no. 6, 37 ° 46 ' S, 146 ° 40 ' E, 4 December 1976, not given (1 MVMA); Macalister­Thomson River Jn, NMV Survey Dept. GRES T 26 no. 7, 37 ° 46 ' S, 146 ° 40 ' E, 19 February 1977, not given (1 MVMA); Melbourne [no date], 37 ° 58 ' S, 144 ° 58 ' E, (5 BMNH); Morwell River on Driffield ­ Yinnar Rd., S 43, LaTrobe C. Survey, 38 ° 19 ' S, 146 ° 19 ' E, 6 December 1978, [not given] (5 MVMA); Narracan Ck. at Cooks Rd., 2.3 km NW Thorpdale, in gravel at edge of gravelly riffle of small creek flowing through pasture, elev. 135 m, 38 ° 16 ' S, 146 ° 10 ' E, 4 February 1999, N. Porch (NP 28) (8 ANIC); Nathalia, 36 ° 3 ' S, 145 ° 12 ' E, 18 January 1961, C. Watts (1 SAMA); Porepunkah, Ovens R., mixed dry sclerophyll and exotic trees; at UV light near river; FMHD # 87 ­ 273, elev. 300 m, 36 ° 42 ' S, 146 ° 55 ' E, 12 February 1987, A. Newton & M. Thayer (837) (5 FMNH); Spargo Creek, W. of, firedam nr Centre Track, clayey mud at edge of small firedam in pine forest, elev. 705 m, 37 ° 27 ' S, 144 ° 5 ' E, 17 February 2002, N. Porch (92) (3 ANIC); Tarago R. at Elston Rd., 1.75 km W Neerim, ex silty sand patches between waterside vegetation and wet litter along edge of riffle. Dry sclerophyll forest­pasture, elev. 170 m, 38 ° 28 ' S, 145 ° 56 ' E, 15 January 1999, N. Porch (NP 20) (109 ANIC); Tarago River, Bellbird Park at old Princes Highway, ex sandy mud and litter in sun along edge of slow flowing river in pasture, elev. 50 m, 38 ° 5 ' S, 145 ° 48 ' E, 15 January 1999, N. Porch (NP 21) (2 ANIC); Thomson River at Heyfield, wet gravel at edge of river flowing through pasture, elev. 40 m, 37 ° 59 ' S, 146 ° 46 ' E, 1 December 1999, N. Porch (55) (38 ANIC); Thomson River, Cowwarr­Seaton Rd, NMV Survey Dept. GRES T 24 no. 3, river, 37 ° 41 ' S, 146 ° 13 ' E, 4 December 1976, not given (1 MVMA); Upper Yarra Dam, 37 ° 40 ' S, 145 ° 53 ' E, 28 February 1976, A. Neboiss (6 MVMA); Woori Yallock Ck., at Warburton Highway, ex muddy margins of undercut creek banks near water level; pasture, elev. 110 m, 37 ° 47 ' S, 145 ° 31 ' E, 23 February 1999, N. Porch (NP 35) (35 ANIC); Woori Yallock Creek on road to Warburton, 37 ° 44 ' S, 145 ° 29 ' E, 5 December 1972, P. Zwick (1 MCZ); ' Yarra Flats', Eaglemont (Melbourne suburb), ex mud at edge of small drying ' billabong' in parklands, elev. 15 m, 37 ° 46 ' S, 145 ° 4 ' E, 26 February 1999, N. Porch (NP 37) (445 ANIC); Yarra River, 4.5 km SW Healesville, dry sclerophyll forest; UV blacklight along river; FMHD # 87 ­ 259, elev. 80 m, 37 ° 41 ' S, 145 ° 29 ' E, 6 February 1987, A. Newton & M. Thayer (825) (4 FMNH); Yellow Creek, at crossing of Ovens Highway, Wangaratta, coarse sand and gravel at wet margins of gravel bar of red gum lined creek in pasture, elev. 145 m, 36 ° 21 ' S, 146 ° 20 ' E, 15 December 2001, N. Porch (88) (15 ANIC). Representative specimens to be deposited in CMNH, FMNH, MCZ, NPC, QMBA, USNM, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFCFFCDFEC77C7A68ECF61E.taxon	materials_examined	Type Material. Holotype (male): Australia: Queensland: Cloncurry, 20 ° 42 ' S, 140 ° 30 ' E, 29 April 1963, C. Watts. Deposited in the SAMA. Paratypes (158): Australia: New South Wales: Darling River, shore washing, 23 ° 11 ' S, 141 ° 42 ' E, 1 October 1982, Endrödy­Younga (AU­ 24) [labels read Darling River, but based on geocodes this would be the Diamantinna River] (78 TMSA); Fowlers Gap, shore washing, 30 ° 55 ' S, 141 ° 36 ' E, 3 October 1982, Endrödy­Younga (AU­ 25) (40 TMSA); Gilgandra, 31 ° 42 ' S, 148 ° 40 ' E, 19 November 1992, C. Watts (1 SAMA); Queensland: Boulia, 22 ° 54 ' S, 139 ° 54 ' E, 1 – 30 July 1972, C. Watts (2 SAMA); Carnarvon Ck. 17 km E Park Office, 25 ° 1 ' S, 148 ° 18 ' E, 14 August 2004, A. Glaister (1 NMW); Cloncurry, 20 ° 42 ' S, 140 ° 30 ' E, 29 April 1963, C. Watts (18 SAMA); Julia Creek, creek, 20 ° 3 ' S, 141 ° 12 ' E, 24 April 1963, C. Watts (6 SAMA); Queensland [no other data], 1 January 1917 – 30 December 1918 (1 NMW); Richmond, 20 ° 56 ' S, 143 ° 20 ' E, 1 October 1917 (1 NMW); same locality, 1 December 1917 (1 NMW); same locality, 1 March 1918 (3 NMW); same locality, 12 March 1918 (2 NMW); same locality, 4 May 1918 (2 NMW); South Australia: Tatiara Ck North of Bordertown, 36 ° 17 ' S, 140 ° 48 ' E, 22 February 1994, Aust. water quality centre 3064 (1 SAMA); Warburton R., 1 km N White Bull Yard Kalamurina Stn., 27 ° 52 ' S, 137 ° 54 ' E, 6 October 1999, WHC exped. (1 SAMA). Representative specimens to be deposited in ANIC, BMNH, CMNH, FMNH, MCZ, MVMA, NPC, QMBA, QPIM, USNM, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFCFFCDFEC77C7A68ECF61E.taxon	diagnosis	Differential Diagnosis. A highly shining species recognized by the pronotum with distinct median groove and lacking posterior foveae, the markedly striate­impressed elytral series, and the large, rhomboidal metasternal glabrous area. Distinguished from G. radiatus, the only other species lacking posterior pronotal foveae, by the distinct pronotal median groove, the smaller lateral depressions of the pronotum, and the more deeply impressed elytral striae. Both species have the abdominal hydrofuge pubescence reduced to lateral areas of the first and second ventrites. The male genitalia of the two species bear some resemblance, but differ in several details, including shapes of the lobes and duct (Fig. 26, 28).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFCFFCDFEC77C7A68ECF61E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) l. 60 / 0.75; head 0.30 / 0.44; pronotum 0.37 / 0.59; elytra 1.11 / 0.75. Form moderately ovate, convex, especially transversely convex on elytra. Color brown to dark brown, dorsal surface very shiny, non­microreticulate. Head shiny, frons very finely sparsely punctate; interocular foveae deep, transverse; interocular tuberculi distinct, transverse; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength equal apical width, very sparsely punctate. Labroclypeal suture weakly bisinuate in dorsal view, evenly arcuate in anterior view. Labrum width twice length, anterior margin arcuate, apicomedially raised in form of very small tooth (both sexes). Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum weakly bisinuate; each lateral depression weakly convex, with posterior angle obtuse, not markedly produced to form small point, lateral margin densely setose, weakly arcuate; lateral fossulae shiny, moderately deep, lacking microsculpture, terminating anteriorly in a small pit; pronotal disc transversely convex, very shiny, extremely finely sparsely punctate, almost glabrous, each puncture with a minute recumbent seta; median groove moderately deep, very narrowly incised, highlighted by brightly shining cuticle at edges, extending nearly to margins, tapering at ends; anterior foveae very small, pit­like; posterior foveae absent; posterolateral angles lacking impressions. Elytra very transversely convex on disc, with six rows of punctures in moderately well developed striae between suture and humeri; intervals shiny, rounded, width 2 – 3 times that of punctures; punctures very small, slightly elongate, separated from each other by about puncture length, lacking discernible setae; summit of declivity at or slightly in front of midlength; sides of elytra nearly vertical in posterior 1 / 4, apices separately rounded; striae 2 and 3 terminating into 4 at about apical 1 / 4; elytral explanate margin very narrow, with distinctive fringe of short setae. Metasternal glabrous area length less than width (as 16: 22), subrhomboidal, anteriorly nearly attaining intercoxal process, shining, convex. Abdominal ventrites 1 – 2 laterally with hydrofuge pubescence, absent in midline; perhaps minutely present basolaterally on 3. Aedeagus (Fig. 28): Length of main­piece 0.31 mm, parameres attaining same level; lobes relatively long, weakly barbed subapically; notch nearly parallel sided; duct relatively large; apical paramere seta short. Females have the elytral explanate margin similar to that of males; the labrum has an apicomedian tooth, smaller than that of males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFCFFCDFEC77C7A68ECF61E.taxon	etymology	Etymology. Named in reference to the very lustrous pronotal disc, which highlights the median sulcus.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFCFFCDFEC77C7A68ECF61E.taxon	distribution	Distribution. Currently known from eastern Queensland south to southeastern South Australia, and one locality in New South Wales (Fig. 73).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF92FFA4FEC779206993F6BE.taxon	materials_examined	Type Material. Holotype (male): Australia: Northern Territory: Palm Valley, 24 ° 4 ' S, 132 ° 45 ' E, 1 – 30 April 1968, C. Watts. Deposited in the SAMA. Paratypes (196): Australia: New South Wales: Wilcannia, 5 km E of, at Darling River, sandy mud at edge of river, elev. 70 m, 31 ° 34 ' S, 143 ° 25 ' E, 1 September 2000, N. Porch (5) (5 ANIC); Northern Territory: Finke Gorge NP (Boggy Hole), large permanent pool in river bed, grassed and bulrushes at edge, algal growth, 24 ° 9 ' S, 132 ° 52 ' E, 15 March 1995, T. Weir (9 ANIC); Finke Gorge NP (Kanara Ck. at The Oasis), permanent rock pools, palms, grass at edges, algal growth, 24 ° 4 ' S, 132 ° 44 ' E, 12 March 1995, T. Weir (1 ANIC); Finke River at Glen Helen Gorge, West Macdonnells NP, flowing river, large pools, with bulrushes, sandy bottom, algal growth, 23 ° 41 ' S, 132 ° 40 ' E, 10 March 1995, T. Weir (1 ANIC); Finke River at Running Water, at light, 24 ° 20 ' S, 132 ° 53 ' E, 15 March 1995, T. Weir (1 ANIC); Finke River at Running Water, temporary pools in sandy creek bed, 24 ° 20 ' S, 132 ° 53 ' E, 15 March 1995, T. Weir (6 ANIC); Finke River xing, Stuart Highway, flowing river (temporary), sandy base, over­hanging vegetation, 24 ° 33 ' S, 133 ° 14 ' E, 4 March 1995, T. Weir (2 ANIC); Hugh River, 12.5 km SSE of Paisley Bluff, flowing river, deep pool, grass at edges, sandy bottom, 23 ° 49 ' S, 133 ° 22 ' E, 7 March 1995, T. Weir (2 ANIC); Palm Valley, 24 ° 4 ' S, 132 ° 45 ' E, 1 – 30 April 1968, C. Watts (18 SAMA); Simpson Gap, West Macdonnells NP, large pools in flowing creek (temporary) with grass at edge, 20 ° 40 ' S, 133 ° 43 ' E, 6 March 1995, T. Weir (1 ANIC); Queensland: Boulia, 22 ° 54 ' S, 139 ° 54 ' E, 1 – 30 July 1972, C. Watts (2 SAMA); Cape River, 100 km S Charters Towers, river, 21 ° 0 ' S, 146 ° 25 ' E, 12 December 2002, C. H. S. Watts (1 SAMA); Dalrymple, 30 km N Charters Towers, elev. 300 m, 19 ° 49 ' S, 145 ° 44 ' E, 18 January 1993, Wewalka (2 NMW); Pioneer R. nr. Mirani, 21 ° 9 ' S, 149 ° 13 ' E, 4 September 1972, H. E. Hinton (1 ANIC); South Australia: 3 km N Portee Stn. R. Murray, small river nat depression, 34 ° 24 ' S, 139 ° 36 ' E, 19 March 1973, G. F. Gross (2 SAMA); Murray River [no date], river, 34 ° 57 ' S, 139 ° 16 ' E, A. H. Elston (15 AMSA); Murray River, shore washing, 34 ° 57 ' S, 139 ° 16 ' E, 27 November 1982, Endrödy­Younga (AU­ 13) (35 TMSA); R. Murray, 34 ° 57 ' S, 139 ° 16 ' E, 1 – 30 December 1917, R. J. Burton (1 SAMA); Small billabong nr. Mannum, 34 ° 55 ' S, 139 ° 18 ' E, 29 June 1976, R. Shiel (4 SAMA); Victoria: Lake Hattah, 34 ° 44 ' S, 142 ° 21 ' E, 28 February 1967, G. W. Anderson (1 ANIC); Loddon River at Newstead, gravel at edge of small river flowing through pasture, elev. 210 m, 37 ° 6 ' S, 144 ° 3 ' E, 27 November 1999, N. Porch (47) (67 ANIC); McKillops Bridge, Snowy River, gravel at edge of large and rising river; dry sclerophyll forest, elev. 185 m, 37 ° 5 ' S, 148 ° 23 ' E, 6 November 2000, N. Porch (NP 16) (4 ANIC); Murray River [no date], 34 ° 57 ' S, 139 ° 16 ' E, not given (7 SAMA); Sea Lake [no date], 35 ° 29 ' S, 142 ° 50 ' E, Goudie (1 UQIC); Wimmera River at Western Highway, muddy sand at edge of river pool in dry sclerophyll / riverine forest, elev. 100 m, 36 ° 25 ' S, 141 ° 58 ' E, 1 March 2000, N. Porch (61) (1 ANIC); Wyperfeld National Park, Frew’s Plain, at light, 35 ° 37 ' S, 142 ° 1 ' E, 15 – 17 November 1973, S. Misko (4 ANIC); Western Australia: Synnot Ck., CALM Site 25 / 1 [Western Australian Department of Conservation and Land Management], at light, open forest, 16 ° 31 ' S, 125 ° 16 ' E, 17 – 20 June 1988, T. A. Weir (1 ANIC). Representative specimens to be deposited in AMSA, BMNH, CMNH, FMNH, MCZ, MVMA, NPC, QMBA, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF92FFA4FEC779206993F6BE.taxon	diagnosis	Differential Diagnosis. Recognized by the markedly microreticulate head and pronotal foveae, the pronotal reliefs sparsely but distinctly punctate over effacedly microreticu­ late ground sculpture, the striate­impressed elytral series, the abdominal ventrites 1 – 2 and basal part of 3 with hydrofuge pubescence, and the brown dorsum with metallic reflections. The male genitalia have the apices of the lobes shaped similar to those of G. angulonotus, but other features of the genitalia differ (Figs. 6, 57), and the two species differ markedly in habitus (Figs. 5, 56).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF92FFA4FEC779206993F6BE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.75 / 0.63; head 0.37 / 0.44; pronotum 0.37 / 0.56; elytra 1.07 / 0.63. Form moderately ovate, moderately convex. Pronotum and elytra brown with slight metallic reflections, head black, entire dorsal surface dull. Head microreticulate; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength about equal apical width, very sparsely pubescent laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length, anterior margin with small apicomedian tooth. Maxillary palpomere 3 slightly greater than twice length of 4, slightly swollen. Pronotum with impressions strongly microreticulate, reliefs effacedly microreticulate; lateral hyaline border well developed, origin at base of lateral depression, weakly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression with posterior angle about right, not produced in acute point, lateral margin arcuate, setose; lateral fossulae deep; pronotal disc moderately convex, reliefs sparsely but distinctly punctate over effacedly microreticulate ground sculpture, some punctures with short indistinct recumbent seta; median groove moderately deep and wide, slightly narrowed in midlength, extending nearly to margins, tapering slightly apically, widening slightly basally; anterior foveae large and deep, wider than median groove; posterior foveae oblique, deep linear impressions slightly greater than 1 / 2 as long as and nearly twice as wide as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, with six rows of closely spaced slightly elongate punctures in well developed striae between suture and humeri; intervals rounded, width about equal that of punctures; summit of declivity slightly behind midlength; striae 2 and 3 terminating into 4 at about apical 1 / 4; elytral explanate margin narrow, lacking prominent setae. Metasternal glabrous area length less than width (as 15: 20), subrhomboidal, shining, very sparsely punctate, convex. Abdominal ventrites 1 – 2 and basal part of 3 with hydrofuge pubescence. Aedeagus (Fig. 57): Length of main­piece 0.26 mm, length to tip of parameres 0.28 mm; lobes moderately long, in oblique view each lobe pointed at apex and with small barb of similar size near apex; dorsal notch U­shaped, wider than V­shaped ventral notch; duct large compared to notch, apically truncate in lateral aspect; apical paramere seta elongate, ca. 2 – 3 x length of next longest setae. Females have the elytral explanate margin similar to that of males; the anterior margin of the labrum is weakly apicomedially emarginate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF92FFA4FEC779206993F6BE.taxon	etymology	Etymology. Named in reference to the distinctive microsculpture.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF92FFA4FEC779206993F6BE.taxon	distribution	Distribution. A widely distributed species, being found in portions of Victoria, South Australia, western New South Wales, southern Northern Territory, Queensland, and one locality in Western Australia (Fig. 76).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9BFFAEFEC7791A6908F61E.taxon	materials_examined	Type Material. Holotype (male): Australia: Northern Territory: Roderick Creek, Gregory N. P., M. V. Light, Operation Raleigh 1986, 15 ° 38 ' S, 131 ° 22 ' E, 4 – 6 July 1986, I. Archibald. Deposited in the MAGD.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9BFFAEFEC7791A6908F61E.taxon	diagnosis	Differential Diagnosis. Recognized by the small size, the short and slightly thickened dorsal setae, the fringe of arcuate setae on the elytral lateral margins, and the microreticu­ late dorsum (Fig. 64). Similar to G. squamifer (Fig. 66) in having abdominal hydrofuge pubescence reduced to the first two ventrites, but differing in larger size, narrower dorsal setae, narrower fringe of setae on the elytra, smaller elytral punctures, discrete elytral intervals as wide as serial punctures, non­confluent anterior­posterior pronotal foveae, and abdominal hydrofuge restricted to the 1 st ventrite and all of the 2 nd except the apical edge. The male genitalia of the two species are quite distinct (Figs. 65, 67).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9BFFAEFEC7791A6908F61E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.41 / 0.63; head 0.22 / 0.41; pronotum 0.37 / 0.56; elytra 0.86 / 0.63. Form moderately ovate, convex. Color dark brown, dorsum weakly shining, with distinctive short whitish or yellowish setae. Head with dorsum clothed in distinctive recumbent setae near eyes and laterally on frons; frons finely sparsely punctate; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength about 0.5 apical width, finely sparsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width three times length, anterior margin arcuate, with apicomedian upturned tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate between lateral depressions; each lateral depression with posterior angle slightly acute, lateral margin weakly arcuate, densely clothed in setae which overlap one another; lateral fossulae deep, terminating anteriorly in pit; pronotal disc moderately convex, very effacedly microreticulate and finely sparsely punctate, each puncture with a distinctive recumbent whitish seta which contrasts with dark cuticle; median groove moderately deep and wide, constricted in midlength, wider anteriorly than posteriorly, extending nearly to margins, tapering at ends; anterior foveae well developed, deep; posterior foveae oblique, linear impressions 1 / 2 as long as and about as wide as median groove; posterolateral angles lacking impressions. Elytra quite convex on disc; six rows of non­striate impressed punctures between suture and humeri, punctures closely spaced and nearly as wide as intervals; each puncture with a distinctive short narrow flat decumbent seta; summit of declivity at midlength; sutural margin slightly raised; elytral explanate margin very narrow, with fringe of arcuate setae over anterior 0.5. Metasternal glabrous area slightly wider than long, subrhomboidal. Abdominal ventrites 1 and all of 2 except apical edge with hydrofuge pubescence. Aedeagus (Fig. 65): Length of main­piece 0.25 mm, parameres not extending beyond main­piece; lobes long, barbed well before apices which are slightly bent; notch narrowed slightly apically; apical paramere setae short, subequal in length. Females unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9BFFAEFEC7791A6908F61E.taxon	etymology	Etymology. Named in reference to the small size and setose dorsum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9BFFAEFEC7791A6908F61E.taxon	distribution	Distribution. Currently known only from the type locality in Gregory National Park, Northern Territory (Fig. 74).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE1FFD0FEC77A926F6AF3B6.taxon	materials_examined	Type Material. Holotype (male): Australia: Victoria: Possum Hollow falls, W. br. Tarwin River, 5.6 km SSW Allambee, ex sandy mud between cobbles at edge of riffle 0.1 km below waterfall; wet sclerophyll forest (Eucalyptus regnans), elev. 240 m, 38 ° 19 ' S, 146 ° 1 ' E, 14 January 1999, N. Porch (NP 18). Deposited in the ANIC. Paratypes (108): Australia: Victoria: 1 km N Possum Hollow, W. br. Tarwin River, 4.6 km SSW Allambee, ex shaded silty mud at edge of small ' creek' at pasture­wet sclerophyll forest boundary, elev. 240 m, 38 ° 18 ' S, 146 ° 1 ' E, 14 January 1999, N. Porch (NP 19) (56 ANIC); Bunyip R. at Princes Highway, amongst willow roots and on sand at edge of river under thick wil­ low cover in pasture, elev. 40 m, 38 ° 5 ' S, 145 ° 45 ' E, 15 January 1999, N. Porch (NP 22) (1 ANIC); Diamond Ck., 1.8 km NNE Tonimbuk, on fine­medium sand and amongst litter on sandbar in small creek flowing through dry sclerophyll forest, elev. 110 m, 37 ° 59 ' S, 145 ° 42 ' E, 4 February 1999, N. Porch (NP 25) (1 ANIC); Elizabeth Ck., 1.2 km S Childers, very abundant in sandy mud and wet litter (80 cm by 20 cm) along edge of small forest creek in wet sclerophyll forest (Eucalyptus regnans), elev. 195 m, 38 ° 19 ' S, 146 ° 6 ' E, 28 October 1998, N. Porch (NP 09) (2 ANIC); Elizabeth Ck., 1.5 km N Allambee South, mud at edge of creek flowing under shady willows, elev. 125 m, 38 ° 20 ' S, 146 ° 7 ' E, 11 September 1998, N. Porch (NP 05) (8 ANIC); Little Morwell River at Mirboo Nth ­ Morwell Rd., 3.75 km NNE Mirboo North, on and in shaded muddy sand at edge of ' small creek' in dry sclerophyll forest, elev. 165 m, 38 ° 22 ' S, 146 ° 11 ' E, 14 October 1998, N. Porch (NP 08) (2 ANIC); Morwell River on Boolarra­Morwell Rd., S 43, LaTrobe C. Survey, river, 38 ° 19 ' S, 146 ° 19 ' E, 5 December 1978, [collr. not given] (3 MVMA); Possum Hollow falls, W. br. Tarwin River, 5.6 km SSW Allambee, ex sandy mud between cobbles at edge of riffle 0.1 km below waterfall; wet sclerophyll forest (Eucalyptus regnans), elev. 240 m, 38 ° 19 ' S, 146 ° 1 ' E, 14 January 1999, N. Porch (NP 18) (8 ANIC); Yarra River at Launching Place, margin of Yarra River on silty fine sand, elev. 115 m, 37 ° 47 ' S, 145 ° 35 ' E, 23 February 1999, N. Porch (NP 36) (27 ANIC). Representative specimens to be deposited in BMNH, CMNH, FMNH, MCZ, MVMA, NMW, NPC, and QMBA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE1FFD0FEC77A926F6AF3B6.taxon	diagnosis	Differential Diagnosis. Recognized by the very convex dorsum, the cuticular transparency, the arcuate anterior pronotal margin, the shining, very finely sparsely punctate pronotal reliefs, the strongly punctate elytra, and the distinctive fringe of long but rather sparse setae on the elytral margin (Fig. 31). Distinguished from G. trilineatus, which is also quite convex dorsally, by the non­confluent pronotal foveae. The male genitalia of the two species show some similarity, both lacking barbs, but in G. nicki the parameres are shorter, the lobes more rounded, the notch shallower, and the main­piece subapically wider (Figs. 30, 32).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE1FFD0FEC77A926F6AF3B6.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.79 / 0.78; head 0.33 / 0.48; pronotum 0.41 / 0.63; elytra 1.11 / 0.78. Form moderately ovate, convex, especially transversely convex on elytra. Color brown with some transparency, head dark brown or piceous, dorsal surface shiny, non­microreticulate. Head shiny, frons very finely sparsely punctate, sparsely pubescent; interocular foveae deep, pubescent; interocular tuberculi indistinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width: length as 7: 2, anterior margin broadly and shallowly emarginate, apicomedially raised in form of very small tooth (male only). Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression with posterior angle produced to form small point, lateral margin setose, weakly arcuate; lateral fossulae shiny, deep, lacking microsculpture; pronotal disc transversely convex, shiny, extremely finely sparsely punctate, each puncture with a recumbent seta; median groove deep, moderately wide, extending nearly to margins, tapering at ends; anterior foveae oval, each separated from posterior fovea by 1 – 2 times length of anterior fovea; posterior foveae oblique, deep, linear impressions 1 / 2 as long as and as wide as median groove; posterolateral angles lacking impressions. Elytra very convex on disc, with six rows of punctures in moderately well developed striae between suture and humeri; intervals shiny, rounded, width slightly greater than that of punctures, with sparse erect setae, especially behind elytra midlength; punctures round, separated from each other by about puncture width, each with a recumbent seta; summit of declivity at or slightly in front of midlength; sides of elytra nearly vertical in posterior 1 / 4, apices conjointly sharply rounded; striae 2 and 3 terminating into 4 at about apical 1 / 4; elytral explanate margin very narrow, with distinctive fringe of long but rather sparse setae. Metasternal glabrous area length equal width, suboval, shining, slightly convex. Abdominal ventrites 1 – 3 and basally 4 with hydrofuge pubescence. Aedeagus (Fig. 32): Length of main­piece 0.31 mm, length to tip of parameres 0.34 mm; lobes moderately long, slightly widened apically, not barbed; notch U­shaped, widest apically; apical paramere seta ca. 2 x length of other longer setae. Females are similar to males in form of the elytral explanate margin; the labrum is apicomedially emarginate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE1FFD0FEC77A926F6AF3B6.taxon	etymology	Etymology. Named in honor of the collector, Nicholas Porch.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE1FFD0FEC77A926F6AF3B6.taxon	distribution	Distribution. Currently known from southern Victoria (Fig. 81).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEEFFA2FEC77DA26AB7F1EE.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: In runoff from Mound Spring near Coward Springs, 29 ° 24 ' S, 136 ° 47 ' E, 3 March 1975, E. W. Matthews. Deposited in the SAMA. Paratypes (38): Australia: South Australia: 36 km ESE of Curdimurka, 29 ° 36 ' S, 137 ° 26 ' E, 21 September 1972, J. Upton (1 ANIC); 6 km SE Blanche Cup, Mound Springs, spring, 29 ° 24 ' S, 136 ° 47 ' E, 16 May 1981, J. A. Forrest (6 SAMA); In runoff from Mound Spring near Coward Springs, 29 ° 24 ' S, 136 ° 47 ' E, 3 March 1975, E. W. Matthews (31 SAMA). Representative specimens to be deposited in MCZ, NPC, QMBA, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEEFFA2FEC77DA26AB7F1EE.taxon	diagnosis	Differential Diagnosis. Recognized by the black head contrasting with the testaceous to light brown pronotum and elytra, the lack of a prominent setal fringe on the elytral margin, and the weakly shining or dull dorsum. Sharing with G. fontinalis the anteriorly extended lateral hyaline border, the distinctive abdominal hydrofuge pattern where the hair­line forms a very discrete arc on the fifth ventrite, and the females having a spinose last tergite. Differing from G. fontinalis in having the pronotal disc less coarsely punctate, the dorsum slightly more convex, the body slightly wider and less parallel­sided, the coloration, and in females the arcuate last tergite (Figs. 50, 52). The male genitalia of the two species also show a relationship, but differ significantly in several features, including lobe and duct shapes, and the shorter length in G. nigriceps (Figs. 51, 53).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEEFFA2FEC77DA26AB7F1EE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 2.12 / 0.90; head 0.33 / 0.48; pronotum 0.48 / 0.71; elytra 1.34 / 0.90. Form moderately ovate, moderately convex. Pronotum, elytra and appendages testaceous, head black. Dorsum dull or weakly shining. Head with frons coarsely punctate on disc, microreticulate throughout, setae recumbent, long and yellowish; interocular foveae shallow; interocular tuberculi indistinct; basomedial fovea shallow, confluent with interocular foveae. Frontoclypeal suture moderately deeply impressed, bisinuate. Clypeus midlength 0.5 x apical width, moderately punctate on disc, microreticulate throughout; pubescence on disc similar to frons. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width slightly greater than twice length, anterior margin shallowly emarginate. Maxillary palpomere 3 three times length of 4. Pronotum lateral hyaline border well developed, origin at anterior 0.33 of lateral depression, margin straight, then arcuate at posterior angles, narrow around posterior margin; anterior margin of pronotum straight or weakly arcuate in midregion; each lateral depression microreticulate, punctate and with yellowish setae, lateral margin more densely setose, lateral margin produced in obtuse point at about midlength, posterior angle acute; lateral fossulae moderately deep, microreticulate; pronotal disc weakly convex, moderately coarsely, moderately densely punctate, each puncture with a recumbent yellow seta; median groove shallow, narrow, extending nearly to margins, tapering at ends; anterior foveae well developed, oval; posterior foveae shallow, oblique, 1 / 2 as long as and twice as wide as median groove; posterolateral angles without impressions. Elytra elongate, weakly convex on disc, with six rows of closely spaced punctures between suture and humeri, each puncture with a yellowish recumbent seta; intervals flat, effacedly microreticulate, width twice that of punctures, punctures round, separated from each other by 0.5 – 1.0 x puncture width; posterior declivity gradual, summit at about 0.66 of length; striae 2 and 3 terminating into 4 at about apical 1 / 4; elytral explanate margin very narrow, with short decumbent indistinct setae, not forming a fringe. Metasternal glabrous area longer than wide (as 20: 15), elongate oval, shining, convex. Abdominal ventrites 1 – 4 and part of 5 with hydrofuge pubescence; on 5 pubescence laterally and basally, forming a very discrete arc­shaped non­pubescent area. Aedeagus (Fig. 51): Length of main­piece 0.47 mm, paramere tips very slightly beyond tips of lobes; lobes relatively long, not barbed, apically roundly acute; ventral notch V­shaped, with sinuate margins, dorsal notch wider, U­shaped; duct asymmetrical, apically pointed in ventral aspect, truncate in lateral aspect; paramere setae clustered at and near apex, apical setae short, longest seta ca. 2 x length of next longest. Females have the explanate elytral margin markedly arcuate, about twice as wide as it is in males, as wide as the mesotibia; the elytral sutural margins are sometimes weakly emarginate just before the apices, forming a narrow gap between the elytra; the anterior margin of the labrum is apicomedially weakly emarginate; the last abdominal tergite has a prominent fringe of spine­like setae.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEEFFA2FEC77DA26AB7F1EE.taxon	etymology	Etymology. Named in reference to the dorsal coloration.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEEFFA2FEC77DA26AB7F1EE.taxon	distribution	Distribution. Currently known from two closely spaced localities in central South Australia (Fig. 92).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCEFFC3FEC77DA26AA3F61E.taxon	description	(Figures 11, 12, 73)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCEFFC3FEC77DA26AA3F61E.taxon	materials_examined	Type Material. Holotype (male): Australia: Western Australia: Bunbury [labels: " Type "; " Ochthebius notalis Deane. (descr. publishd.) det. C. Deane. p. 24 fig. 7 "]. Deposited in the UQIC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCEFFC3FEC77DA26AA3F61E.taxon	diagnosis	Differential Diagnosis. Recognized by the coarsely densely punctate pronotum, the narrow median groove, the comparatively narrow weakly convex elytra, and the elytral intervals wider than the shallowly striate­impressed elytral series. This species shows some superficial resemblance to G. lividus, but is smaller (ca. 1.67 mm vs. 2.00 mm), differently colored, more coarsely punctate, and does not have an anterior extension of the pronotal lateral hyaline border. The male genitalia of the two species are very different (Figs. 10, 12).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCEFFC3FEC77DA26AA3F61E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.67 / 0.71; head 0.33 / 0.44; pronotum 0.40 / 0.58; elytra 1.12 / 0.71. Form elongate oval, weakly convex. Color dark brown to black (holotype teneral, brown), dorsal reliefs moderately shining. Frons very finely sparsely punctate on median relief, more coarsely punctate laterally, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal midlongitudinal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, moderately coarsely densely punctate, especially in basal 0.5; pubescence sparse and short. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 2.5 x length; anterior margin arcuate, with very low upturned apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression with posterior in form of right angle, lateral margin with fringe of short arcuate setae; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, moderately coarsely densely punctate, each puncture with a very indistinct recumbent seta; median groove deep, narrow, not attaining anterior or posterior margins, tapering at ends; anterior foveae deep, small; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and nearly twice as wide as median groove; posterolateral angles without indistinct shallow impressions. Elytra transversely weakly convex on disc, longitudinally nearly flat, with six rows of closely spaced punctures in shallow striae between suture and humeri; each puncture with a decumbent or recumbent seta that overlaps base of following seta; intervals flat or slightly rounded, width 1.0 – 1.5 that of punctures; intervals lacking prominent setae; elytra sides weakly arcuate, margin lacking fringe of setae; explanate margin narrow; posterior declivity gradual, summit slightly behind midlength; elytra narrowed slightly preapically, apices conjointly sharply rounded. Metasternal glabrous area length equal width, oval in females, widest behind midlength in males, shining, nearly flat. Abdominal ventrites 1 – 3 and basally 4 with hydrofuge pubescence. Aedeagus (Fig. 12): Length of main­piece 0.26 mm, length to tip of parameres 0.30 mm; main­piece wide in ventral aspect, slightly narrowed near midlength in oblique aspect; lobes relatively long, sharply rounded apically, strongly barbed; notches U­shaped, ventral notch deeper than dorsal notch; duct asymmetrical in ventral aspect, truncate at apex in oblique aspect; apical paramere seta elongate, ca. 2 x length of next longest seta. Females have the explanate elytral margin very slightly if at all wider than that of males; the anterior margin of the labrum is arcuate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCEFFC3FEC77DA26AA3F61E.taxon	distribution	Distribution. Currently known from southern and western Western Australia (Fig. 73).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCEFFC3FEC77DA26AA3F61E.taxon	materials_examined	Material Examined (157): Australia: Western Australia: 20 km EbyN of Esperance, at light, 33 ° 50 ' S, 122 ° 6 ' E, 8 November 1977, J. F. Lawrence (2 ANIC); Belmont, Perth, 31 ° 33 ' S, 115 ° 41 ' E, 3 January 1954, H. Demarz (4 FMNH); Bridgetown, 34 ° 1 ' S, 116 ° 0 ' E, 9 November 1931, P. J. Darlington (4 MCZ); Bunbury [no date], 33 ° 20 ' S, 115 ° 38 ' E, Whitlock (4 AMSA, 24 UQIC); Burns Beach, 31 ° 43 ' S, 115 ° 43 ' E, 27 October 1969, D. D. Giuliani (4 ANIC); Esperance, 33 ° 51 ' S, 121 ° 53 ' E, 1 – 30 March 1972, P. Zwick (19 MCZ); Geraldton, 28 ° 46 ' S, 114 ° 36 ' E, 1 – 30 October 1931, P. J. Darlington (1 MCZ); L. Clifton, 32 ° 50 ' S, 115 ° 43 ' E, 1 – 30 March 1972, P. Zwick (13 MCZ); L. Walyungup, 32 ° 20 ' S, 115 ° 46 ' E, 1 – 30 March 1972, P. Zwick (3 MCZ); Murchison R., 27 ° 49 ' S, 114 ° 41 ' E, 28 April 1971, E. F. Riek (1 ANIC); Murchison River, 24 k N Binnu, river, 27 ° 49 ' S, 114 ° 40 ' E, 18 May 2001, C. H. S. Watts (13 SAMA); Parry’s Inlet turnoff on Denmark Rd., 14 mi. E of Denmark, roadside pond, 35 ° 1 ' S, 117 ° 9 ' E, 9 November 1969, E. B. Britton (50 ANIC); Preston River [no date], 33 ° 19 ' S, 115 ° 40 ' E, Whitlock (9 UQIC); Stream on road to Williams Bay, 24 September 1965, E. Britton (4 ANIC); Yanchep., 32 mls. N Perth, 31 ° 33 ' S, 115 ° 41 ' E, 13 – 23 November 1935, R. E. Turner (1 BMNH). Representative specimens to be deposited in CMNH, FMNH, MCZ, NPC, QMBA, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFDAFFEEFEC77DDA6E4AF586.taxon	description	Description. Form generally elongate oval, some members sub­truncate, moderately to strongly convex. Size length / width (mm) varying from about 2.24 / 1.00 to 1.20 / 0.64. Females generally slightly larger than males. Color testaceous to brown to black, dorsum sometimes with metallic reflections. Head varied from nearly impunctate and shiny to coarsely punctate and markedly microreticulate. Interocular foveae moderately developed. Interocular tuberculi (ocelli) evident. Clypeus length of most adults 1 / 2 width, sides convergent anteriorly. Labrum of most males upturned apicomedially, less so or not upturned in females. Maxillary palpus short, palpomere 3 distinctly thickened. Mentum width generally equal length, anterior margin straight or slightly arcuate to rear. Genae shining, swollen. Antennomeres nine (4 + 5). Pronotum with well developed lateral hyaline margin, sclerotized portion varied from non­incised in anterior 1 / 2 to deeply incised. Anterior margin usually slightly bisinuate in habitus view, anterior angles often lobe­shaped. Lateral depressions usually impressed for length of pronotum, infrequently reduced to small foveae at anterior. Pronotal disc usually with well developed anterior and posterior foveae, and median groove; infrequently posterior foveae and median groove obsolete. Prosternum with median carina ended at coxal cavities; coxae contiguous. Metasternum hydrofuge pubescent in midregion or not. Elytra generally with six prominent rows of punctures between suture and humeri, each puncture with a seta; setae usually slender, infrequently widened and flattened; serial punctures infrequently absent or greatly reduced; microreticulation varied from very coarse to absent. Explanate margin varied, sometimes with distinctive fringe of setae. Abdomen with hydrofuge pubescence on ventrites varied, usually first five pubescent, sometimes reduced to first four, first three or first two. Ventrite seven frequently with admedian row of setae. Legs varied from moderately long and slender to short and stout, spines varied from thin and dense to stout and sparse. Males without distinctive protarsal pads of suction setae; metatibiae unmodified. Aedeagus with main­piece bifid, internal structure tubuliform or cupuliform, placed in lumen between forks; parameres varied in length, usually extended slightly beyond main­piece, sometimes extending well beyond, and infrequently terminating at level of tips of main­piece. Spermatheca varied. Antennal pocket (terminology as in Perkins, 1997) hypomeral, wide, smooth except for anteromedial asperite hydrofuge area. Hypomeral, lateral, anterior, and posterior hyaline borders all well developed. Hypomeral antennal pocket setae comparatively long, extending beyond the hypomeral hyaline border. Wet hypomeron small. Postocular area near posteroventral angle of eye with secretion sulcus and slender, arcuate secretion delivery setae. Genal hydrofuge asperite. Periocular pores present adjacent to the eye facets.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9FFFB2FEC77932695BF5E1.taxon	materials_examined	Type Material. Holotype (male): Papua New Guinea: Morobe District, ca. 10 km S Garaina Saureri, elev. 1600 m, 24 March 1998, leg. A. Riedel. Deposited in the NMW. Paratypes: same data as holotype (23 NMW). Representative specimens to be deposited in ANIC, MCZ, NPC, QMBA and SAMA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9FFFB2FEC77932695BF5E1.taxon	diagnosis	Differential Diagnosis. A very distinctive species, recognized by the impunctate head and pronotum contrasting with the deeply punctate elytra, the small apicomedian process of the anterior pronotal margin, the deep pronotal foveae, the wide lateral pronotal depressions, and the diamond­shaped anterior part of the median groove. Markedly differing from G. bacchusi, the other species known from Papua New Guinea, in body form, pronotal form and sculpture, and aedeagus (Figs. 33, 34, 70, 71).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9FFFB2FEC77932695BF5E1.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.58 / 0.74; head 0.31 / 0.43; pronotum 0.38 / 0.63; elytra 0.94 / 0.74. Form moderately ovate, pronotum transverse, elytra strongly convex. Color brown, head darker, dorsal reliefs weakly shining. Head impunctate dorsally, with short sparse setae, each setal base minutely raised. Frons interocular foveae deep; interocular tuberculi distinct; basal foveae confluent with interocular foveae, medially separated by carina. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 2 x length; anterior margin arcuate, setose, without apicomedian tooth. Maxillary palpomere 3 slightly greater than twice length of 4. Pronotum anterior hyaline border well developed, widest in front of lateral fossulae; lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum produced in small point medially, margin straight and angles slightly posteriorly on each side of point, arcuate at anterior angles; lateral depression wide, each with posterior angle acute point, lateral margin arcuate, with short fringe of setae; lateral fossulae deep, lacking microsculpture, anteriorly with small pit­like fovea bearing minute point on anterior and posterior margins; pronotal disc transversely moderately convex, impunctate, with short sparse setae, most setae with socket minutely raised; median groove deep, wide, extending nearly to margins, tapering at ends, constricted near midlength, anterior part diamond shaped and slightly wider than posterior part; anterior foveae oval, relatively large and deep; posterior foveae deep, elongate, similar in size to posterior part of median groove; posterolateral angles without impressions. Elytra very convex on disc, with six rows of moderately large, deep punctures between suture and humeri, not striate­impressed; punctures each with a distinctive decumbent seta; intervals weakly rounded, if at all, width equal that of punctures; declivity steep, summit near midlength, where elytra are transversely markedly convex; sutural margin slightly raised over posterior declivity; explanate margin moderately narrow, decumbent setae on margin forming very narrow fringe. Metasternal glabrous area circular or nearly so, convex, shining. Short midlongitudinal carina from intercoxal process to glabrous area. Abdominal ventrites 1 – 3 and anteriorly 4 with hydrofuge pubescence. Aedeagus (Fig. 71): Length of main­piece 0.27 mm, length to tip of parameres 0.32 mm; lobes long and distinctively barbed; parameres extending well beyond tips of lobes, slightly widened on medial surface, apical seta only slightly longer than subapical setae. Female last tergite with apical fringe of short, flat, stout, contiguous setae.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9FFFB2FEC77932695BF5E1.taxon	etymology	Etymology. Named in reference to the geographical distribution.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9FFFB2FEC77932695BF5E1.taxon	distribution	Distribution. Currently known from Papua New Guinea. Notes. The type series was heavily coated with debris. During the process of removing the debris from the holotype, some setae on the head and pronotum were unavoidably abraded. The former locations of the setae are indicated by the minutely raised rim of each setal socket (Fig. 70).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF97FFA5FEC77D026FD0F14E.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: Somme Creek, bn Angaston & Sedan, gravelly cobble­bank at small creek in pasture, elev. 420 m, 34 ° 34 ' S, 139 ° 9 ' E, 2 March 2000, N. Porch (62). Deposited in the ANIC. Paratypes (52): Australia: South Australia: 9.6 km N of Hawker, at light, 31 ° 48 ' S, 138 ° 25 ' E, 29 February 1972, E. G. Matthews (1 SAMA); Adelaide [no date], 34 ° 55 ' S, 138 ° 36 ' E, P. D. Morris (4 BMNH); Chambers Gorge, 30 ° 58 ' S, 139 ° 16 ' E, 1 – 30 September 1983, C. Watts (6 SAMA);); Flinders Range [date = “ 96 ”], Denton (1 NMW); Gilbert River Stockport, 34 ° 20 ' S, 138 ° 44 ' E, 5 October 1994, Aust. water quality centre 3448 (2 SAMA); Hookina Ck Mt. Little, 31 ° 44 ' S, 138 ° 24 ' E, 15 November 1994, Aust. water quality centre 3636 (2 SAMA); Murray River, shore washing, 34 ° 57 ' S, 139 ° 16 ' E, 27 November 1982, Endrödy­Younga (AU­ 13) (11 TMSA); Nooltana Ck. 13 km NNW Hawker, 31 ° 47 ' S, 138 ° 22 ' E, 17 May 1981, J. A. Forrest (2 SAMA); Salt Ck at Mangalo, 33 ° 32 ' S, 136 ° 37 ' E, 10 November 1994, Aust. water quality centre 3686 (1 SAMA); Somme Creek, bn Angaston & Sedan, gravelly cobble­bank at small creek in pasture, elev. 420 m, 34 ° 34 ' S, 139 ° 9 ' E, 2 March 2000, N. Porch (62) (22 ANIC). Representative specimens to be deposited in MCZ, MVMA, NPC, QMBA, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF97FFA5FEC77D026FD0F14E.taxon	diagnosis	Differential Diagnosis. Recognized by the strongly punctate dorsum, the elytral serial punctures deep and serially contiguous, the intervals appearing zig­zag due to large serial punctures, and the large, rhomboidal, sub­tabelliform metasternal glabrous area. Distinguished from the somewhat similar G. rhombus by the larger size (ca. 1.93 mm vs. 1.53 mm), the more strongly punctate pronotum, with punctures obscuring the margins of the discal foveae, and the narrower elytral setae (Figs. 58, 60). The male genitalia of the two species also show a relationship, but G. perpunctus differs in having the lobes wider, more apically rounded and with a minute barb, the duct wider compared with the width of the parameres, and the paramere setae longer compared with the width of the notch (Figs. 59, 61).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF97FFA5FEC77D026FD0F14E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.93 / 0.82; head 0.37 / 0.48; pronotum 0.48 / 0.63; elytra 1.22 / 0.82. Form moderately ovate, moderately convex. Color dark brown, dorsal surface strongly punctate, weakly shining between punctures. Head with moderately dense whitish setae; frons densely coarsely punctate; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, densely coarsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width: length as 15: 6, anterior margin arcuate, without apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate in midregion; each lateral depression with posterior angle produced to acute point, lateral margin weakly arcuate from anterior angle, weakly emarginate in front of posterior angle, with short fringe of setae; lateral fossulae deep, microreticulate; pronotal disc moderately convex, coarsely densely punctate, very effacedly microreticulate on reliefs, more strongly microreticulate in foveae; each puncture with a recumbent whitish seta which contrasts with dark cuticle; median groove narrow, deep, extending nearly to margins; anterior foveae large, deep; posterior foveae oblique, 1 / 2 as long as and twice as wide as median groove; posterolateral angles strongly punctate, without impressions. Elytra convex on disc, with six rows of large, deep, serially contiguous punctures between suture and humeri, each puncture with a distinctive decumbent whitish seta; intervals narrower than punctures, zig­zag; posterior declivity abrupt, summit near apical 0.33; striae 2 and 3 terminating into 4 at about apical 0.15; elytral explanate margin narrow, lacking prominent fringe setae. Metasternal glabrous area length equal width, rhomboidal, subtabelliform, anteriorly attaining mesosternal intercoxal process, sparsely punctate. Abdominal ventrites 1 – 3 and minutely basally 4 with hydrofuge pubescence. Aedeagus (Fig. 59): Length of main­piece 0.29 mm, length to tip of parameres 0.32 mm; lobes moderately long, apically arcuate in ventral aspect, truncate in oblique aspect, each with a very minute barb subapically; notches U­shaped, nearly parallel­sided, slightly wider than lobes, dorsal slightly deeper than ventral; duct nearly straight, not expanded apically; apical paramere seta elongate, ca. 2 x length of next longest seta. Females have the explanate elytral margin and the labrum similar to males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF97FFA5FEC77D026FD0F14E.taxon	etymology	Etymology. Named in reference to the markedly punctate dorsum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF97FFA5FEC77D026FD0F14E.taxon	distribution	Distribution. Currently known from southern South Australia (Fig. 88).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9CFFACFEC77A0A6A68F14E.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: Warburton River, 1 km N White Bull Yard Kalamurina Stn., 27 ° 52 ' S, 137 ° 54 ' E, 6 October 1999, WHC exped. Deposited in the SAMA. Paratypes: Same data as holotype (10 SAMA). Representative specimens to be deposited in ANIC, MCZ and NPC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9CFFACFEC77A0A6A68F14E.taxon	diagnosis	Differential Diagnosis. A distinctive, markedly punctate species (Fig. 68) differing from all others by the combination of non­serial elytral punctation, each puncture with a short, slightly widened seta, the relatively flat elytral disc, the subrugulose pronotum, and the strongly densely punctate metasternal tabella. The form of the male genitalia also separates this species from all others in the genus (Fig. 69).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9CFFACFEC77A0A6A68F14E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.60 / 0.67; head 0.30 / 0.41; pronotum 0.41 / 0.52; elytra 1.04 / 0.67. Form moderately ovate, mod­ erately convex. Color dark brown, dorsum dull, with short, basally widened, distinctive setae. Head with dorsum clothed in short decumbent setae; frons coarsely densely punctate; interocular foveae deep; interocular tuberculi indistinct; basomedial fovea broadly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength about 0.5 apical width, moderately coarsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 3 x length, anterior margin without apicomedian tooth. Maxillary palpomere 3 twice length of 4. Pronotum lateral hyaline border well developed, origin at base of lateral depression, weakly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate between lateral depressions; each lateral depression with posterior angle rounded, lateral margin sinuate, with sparse short setae; lateral fossulae very deep, terminating anteriorly in pit; pronotal disc convex, subrugose, punctures small, very dense, each with cuticular point at base of distinctive very short seta which contrasts with dark cuticle; median groove deep and moderately wide, ended before margins, tapering at ends; anterior foveae well developed; posterior foveae oblique, linear impressions as long as and about as deep as and slightly wider than median groove; posterolateral angles lacking impressions. Elytra subrugose, flat on disc, sutural margin raised; punctures random, dense, each with cuticular point at base of distinctive, short, basally widened, decumbent seta; summit of declivity near posterior 0.66; elytral explanate margin narrow, lacking fringe of setae. Metasternal glabrous area length less than width (as 15: 23), flat, tabelliform, subrhomboidal, anteriorly attaining intercoxal process, strongly densely punctate. Abdominal sternites 1 – 2 and basal part of 3 with hydrofuge pubescence. Aedeagus (Fig. 69): Length of main­piece 0.32 mm, parameres very slightly longer; lobes long, barbed, weakly arcuate between apex and barb; duct gradually narrowing apically; paramere seta very short. Females have the explanate elytral margin slightly wider than in males; the labrum anterior margin is arcuate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9CFFACFEC77A0A6A68F14E.taxon	etymology	Etymology. Named in reference to the raindrop­like pattern of the elytral setae.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9CFFACFEC77A0A6A68F14E.taxon	distribution	Distribution. Currently known only from the type locality in South Australia (Fig. 87).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFBFFC9FEC77B3A6A68F1BE.taxon	materials_examined	Type Material. Holotype (male): Australia: Queensland: 31 km NW by N of Longreach, 23 ° 13 ' S, 144 ° 4 ' E, 10 May 1973, M. S. Upton. Deposited in the ANIC. Paratypes (6): Australia: Northern Territory: Roderick Creek, Gregory N. P., M. V. Light, Operation Raleigh 1986, 15 ° 38 ' S, 131 ° 22 ' E, 4 – 6 July 1986, I. Archibald (1 MAGD); Queensland: Burunga, at light, 26 ° 13 ' S, 150 ° 1 ' E, 8 October 1984, I. D. Naumann & J. C. Cardale (1 ANIC); South Australia: Cudlee Creek, 34 ° 50 ' S, 138 ° 49 ' E, 10 November 1996, C. Watts (2 SAMA); Victoria: Nathalia, 36 ° 3 ' S, 145 ° 12 ' E, 18 January 1961, C. Watts (2 SAMA). Representative specimens to be deposited in MCZ and NPC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFBFFC9FEC77B3A6A68F1BE.taxon	diagnosis	Differential Diagnosis. Recognized by the highly shining dorsum, the finely sparsely punctate head and moderately punctate pronotal reliefs, the metasternal glabrous area length equal width, widest at posterior, flat in posterior 0.5, posterior margin very slightly raised, and, in males, the probe­like apicomedian process of the labrum. Dorsal habitus somewhat resembling the highly shining G. resplendens, but distinguished there from by the narrower and less convex body form, the more coarsely punctate pronotum, the more coarsely punctate elytral series, and the lack of a setal fringe on the lateral elytral margins (Figs. 21, 23). The male genitalia of the two species are quite dissimilar (Figs. 22, 24).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFBFFC9FEC77B3A6A68F1BE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) l. 67 / 0.71; head 0.37 / 0.41; pronotum 0.37 / 0.56; elytra 1.00 / 0.71. Form moderately ovate, moderately convex. Body and legs light brown, head dark brown, dorsal surface shining. Head with frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength less than twice apical width, very sparsely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width less than twice length, apicomedian tooth prominent, nearly as long as apical segment of maxillary palpus. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression with posterior angle obtuse, not produced to acute point, lateral margin arcuate, setose; lateral fossulae deep, microsculpture similar to remainder of pronotum; pronotal disc moderately convex, punctures sparse and fine medially, becoming denser and coarser laterally near base, most punctures with a very fine short indistinct seta; median groove deep and wide, extending nearly to margins, tapering at ends; anterior foveae well developed, nearly circular; posterior foveae oblique, 1 / 2 as long as and as wide and deep as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, serial punctures very slightly elongate, closely spaced; intervals rounded, width about equal that of punctures; summit of declivity at about apical 0.6; striae 2 and 3 terminating into 4 at about apical 1 / 4; elytral explanate margin moderately wide, lacking prominent setae. Metasternal glabrous area length equal width, widest at posterior, flat in posterior 0.5, posterior margin very slightly raised. Abdominal ventrites 1 – 3 and basal part of 4 with hydrofuge pubescence. Aedeagus (Fig. 24): Length of main­piece 0.33 mm, length to tip of parameres 0.36 mm; main­piece slender, lobes relatively short, not barbed but tips very weakly bent; ventral notch roundly V­shaped, widest apically, dorsal notch U­shaped, wider and slightly deeper than ventral notch; duct short, simple, in ventral aspect gonopore on left side; apical paramere seta elongate, much longer than other setae. Females unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFBFFC9FEC77B3A6A68F1BE.taxon	etymology	Etymology. Named in reference to the prominent apicomedian process of the male labrum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFBFFC9FEC77B3A6A68F1BE.taxon	distribution	Distribution. Currently known from five widely separated localities (each represented by a male) in South Australia, Victoria, Queensland, and Northern Territory (Fig. 76).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFDFFCFFEC77E426908F586.taxon	materials_examined	Type Material. Holotype (male): Australia: Northern Territory: Roderick Creek, Gregory N. P., M. V. Light, Operation Raleigh 1986, 15 ° 38 ' S, 131 ° 22 ' E, 4 – 6 July 1986, I. Archibald. Deposited in the MAGD.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFDFFCFFEC77E426908F586.taxon	diagnosis	Differential Diagnosis. A highly shining species recognized by the pronotum with only the faintest indication of a median groove, the absence of posterior foveae, the striateimpressed elytral series, and the large, subrhomboidal metasternal glabrous area. Distinguished from G. lustrosulcus, the only other species lacking posterior pronotal foveae, by the obsolete pronotal median groove, the larger lateral depressions of the pronotum, and the wider, slightly more convex body form (Figs. 25, 27). Both species have the abdominal hydrofuge pubescence reduced to lateral areas of the first and second ventrites. The male genitalia of the two species bear some resemblance, but differ in several details, including shapes of the lobes and duct (Figs. 26, 28).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFDFFCFFEC77E426908F586.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.52 / 0.78; head 0.30 / 0.44; pronotum 0.41 / 0.63; elytra 1.00 / 0.78. Form moderately ovate, convex, especially transversely convex on elytra. Color dark brown, marginal band on elytra (modified explanate margin visible in lateral aspect), lighter reddish­brown; dorsal surface very shiny, non­microreticulate. Head shiny, frons very finely sparsely punctate; interocular foveae deep, transverse; interocular tuberculi distinct, transverse; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength equal apical width, very sparsely punctate, very sparsely pubescent. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width slightly greater than length, anterior margin arcuate, small depression in midline behind margin. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum bisinuate; each lateral depression weakly convex, posterior margin weakly concave, posterior angle sharp, not produced to form small point, lateral margin arcuate, densely setose; lateral fossulae shallow, lacking distinct microsculpture but slightly less reflective than surrounding area; pronotal disc transversely convex, very shiny, extremely finely sparsely punctate, almost glabrous, each puncture with a minute recumbent seta; median groove almost absent, very faint line interrupted in midlength; anterior foveae very small, transverse incisions, each confluent with respective lateral fossula; posterior foveae absent; posterolateral angles lacking impressions. Elytra very transversely convex on disc, with six rows of punctures in shallow striae between suture and humeri; intervals shiny, weakly rounded, width 2 – 3 times that of punctures; punctures very small, slightly elongate, separated from each other by about puncture length, each with a minute seta; summit of declivity at or slightly in front of midlength; sides of elytra nearly vertical in posterior 1 / 4, apices conjointly sharply rounded; striae 3 and 4 confluent at about apical 1 / 4; margin not explanate, area flat and wide (in lateral aspect), with distinctive dense fringe of setae. Metasternal glabrous area slightly wider than long, subrhomboidal. Abdominal ventrites 1 and 2 with hydrofuge pubescence laterally, absent medially. Aedeagus (Fig. 26): Length of main­piece 0.28 mm, length to tip of parameres 0.29 mm; lobes relatively long, not barbed, but bent slightly apically; notch narrow, narrowest apically; apical paramere setae much longer than other setae. Females unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFDFFCFFEC77E426908F586.taxon	etymology	Etymology. Named in reference to the highly shining dorsum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFDFFCFFEC77E426908F586.taxon	distribution	Distribution. Currently known only from the type locality in Gregory National Park, Northern Territory (Fig. 74).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF8FFC8FEC77E426964F346.taxon	materials_examined	Type Material. Holotype (male): Australia: Queensland: nr. Westcott Plain, Bunya Mts. Nat. Pk., 26 ° 52 ' S, 151 ° 34 ' E, 6 – 7 October 1984, I. D. Naumann & J. C. Cardale. Deposited in the ANIC. Paratypes (50): Australia: New South Wales: Bogan River, 33 ° 0 ' S, 148 ° 2 ' E, 1 – 30 October 1933, J. Armstrong (2 AMSA); Darling River, 29 ° 57 ' S, 146 ° 18 ' E, 1 May 1925, H. J. Carter (3 ANIC); Darling River, shore washing, 23 ° 11 ' S, 141 ° 42 ' E, 1 October 1982, Endrödy­Younga (AU­ 24) [labels read Darling River, but based on geocodes this would be the Diamantinna River] (23 TMSA); Fowlers Gap, shore washing, 30 ° 55 ' S, 141 ° 36 ' E, 3 October 1982, Endrödy­Younga (AU­ 25) (13 TMSA); Wilcannia, 5 km E of, at Darling River, sandy mud at edge of river, elev. 70 m, 31 ° 34 ' S, 143 ° 25 ' E, 1 September 2000, Rhys Porch (5) (6 ANIC); Queensland: Biloela, 24 ° 24 ' S, 150 ° 30 ' E, 7 September 1972, H. E. Hinton (1 ANIC); Broken River, 50 miles W of Mackay, 19 ° 32 ' S, 144 ° 54 ' E, 30 November 1968, S. Misko (1 ANIC). Representative specimens to be deposited in MCZ, NPC, QMBA, and SAMA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF8FFC8FEC77E426964F346.taxon	diagnosis	Differential Diagnosis. Recognized by the highly shining dorsum, the very finely sparsely punctate pronotal disc without perceptible setae, the large and deep pronotal foveae with smooth, gradually sloping margins, the relatively narrow median groove, the elytral intervals about twice as wide as the serial punctures, and the very slightly acuminate elytral apices. Distinguished from G. australis and G. setosus by the body form, the greatly reduced dorsal setae, and the male genitalia (Figs. 1, 3, 21).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF8FFC8FEC77E426964F346.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.60 / 0.75; head 0.33 / 0.44; pronotum 0.37 / 0.56; elytra 1.04 / 0.75. Form moderately ovate, moderately convex. Color brown, head darker, dorsum markedly shining. Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal impression confluent with interocular foveae, with very fine midlongitudinal line. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length; anterior margin arcuate, with low upturned apicomedian tooth. Maxillary palpomere 3 about twice length of 4. Pronotum shining, very finely sparsely punctate; lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum evenly bisinuate; each lateral depression with posterior angle slightly obtuse, lateral margin with fringe of short setae; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, extremely finely sparsely punctate, each puncture with a minute nearly imperceptible seta; median groove moderately deep, narrow, extending nearly to margins, tapering at ends, sides rather abrupt compared with gradually sloping foveae; anterior foveae well developed, oval, margins gradually sloping; posterior foveae oblique, oval, nearly 1 / 2 as long as and twice as wide as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, sides sloping, not vertical, in midregion, with six rows of slightly elongate, closely spaced punctures between suture and humeri; punctures on disc without perceptible setae, setae laterally and over posterior declivity very short, not attaining adjacent puncture; intervals flat or slightly rounded, width 2.0 – 2.5 x that of punctures; intervals over posterior declivity with very sparse, decumbent setae; summit of declivity near 0.66 length, where elytra are transversely markedly convex; elytral explanate margin very narrow, with fringe of moderately long setae. Metasternal glabrous area length equal width, oval, shining, convex. Abdominal ventrites 1 – 3 and minutely basally 4 with hydrofuge pubescence. Aedeagus (Fig. 22): Length of main­piece 0.26 mm, parameres attaining tips of lobes; lobes relatively long, markedly arcuate on dorsal surface, each with a small subapical barb on ventrolateral surface; notches widest apically, dorsal notch U­shaped, wider and shallower than V­shaped ventral notch; duct slightly enlarged apically and produced in tiny point; apical paramere seta elongate, ca. 2 x length of next longest seta. Females have the elytral explanate margin similar to that of males; the anterior margin of the labrum sometimes has a minute tooth, smaller than that of males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF8FFC8FEC77E426964F346.taxon	etymology	Etymology. Named in reference to the strongly shining dorsum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF8FFC8FEC77E426964F346.taxon	distribution	Distribution. Currently known from widely separated localities in New South Wales and Queensland (Fig. 76).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF96FFABFEC7793269BEF47E.taxon	materials_examined	Type Material. Holotype (male): Australia: Northern Territory: Finke Gorge NP, Palm Valley, small temporary pools, rocky, some sandy base, algal growth, detritus, 24 ° 3 ' S, 132 ° 43 ' E, 14 March 1995, T. Weir. Deposited in the ANIC. Paratypes (2): Australia: Northern Territory: Finke Gorge NP (Boggy Hole), large permanent pool in river bed, grasses and bulrushes at edge, algal growth, 24 ° 9 ' S, 132 ° 52 ' E, 15 March 1995, T. Weir (1 ANIC); Finke River xing, Stuart Highway, flowing river (temporary), sandy base, over­hanging vegetation, 24 ° 33 ' S, 133 ° 14 ' E, 4 March 1995, T. Weir (1 ANIC).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF96FFABFEC7793269BEF47E.taxon	diagnosis	Differential Diagnosis. Recognized by the strongly punctate dorsum, the elytral serial punctures deep and serially contiguous, the intervals appearing zig­zag due to large serial punctures, and the large, rhomboidal, subtabelliform metasternal glabrous area. Distinguished from the somewhat similar G. perpunctus by the smaller size (ca. 1.53 mm vs. 1.93 mm), the less strongly punctate pronotum, the microreticulate discal pronotal foveae with very discrete margins (not obscured by punctures), and the widened pronotal and elytral setae (Figs. 58, 60). The male genitalia of the two species also show a relationship, but G. rhombus differs in having the lobes narrower, more weakly rounded apically, and not barbed, the duct narrower compared with the width of the parameres, and the paramere setae shorter compared with the width of the notch (Fig. 59, 61).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF96FFABFEC7793269BEF47E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.53 / 0.69; head 0.28 / 0.42; pronotum 0.42 / 0.56; elytra 0.93 / 0.69. Form moderately ovate, moderately convex. Color dark brown, dorsal surface dull, strongly punctate, with short whitish setae. Head with moderately dense whitish setae; frons densely coarsely punctate; interocular foveae deep; interocular tuberculi distinct; basomedial fovea not confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, moderately densely coarsely punctate, microreticulate laterally. Labroclypeal suture weakly bisinuate in dorsal view, evenly arcuate in anterior view. Labrum width: length as 15: 6, anterior margin arcuate, without apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate in midregion; each lateral depression with posterior angle produced to acute point, lateral margin weakly arcuate from anterior angle, very weakly emarginate in front of posterior angle, with short fringe of setae; lateral fossulae deep, microreticulate; pronotal disc moderately transversely convex, coarsely densely punctate, not microreticulate on reliefs, weakly microreticulate in foveae; each puncture with a recumbent whitish seta which contrasts with dark cuticle; median groove moderately narrow, deep, constricted slightly in midlength, extending nearly to margins; anterior foveae large, deep; posterior foveae oblique, 1 / 2 as long as and about twice as wide as median groove; posterolateral angles strongly punctate, without distinct impressions. Elytra transversely convex on disc, with six rows of large, deep punctures between suture and humeri; rows 1 – 2 weakly striate­impressed and punctures serially contiguous, rows 3 – 6 with punctures slightly more widely spaced, not striate­impressed; each puncture with a distinctive decumbent short weakly squamose whitish seta; intervals slightly narrower than punctures; posterior declivity only moderately abrupt, summit slightly before midlength; striae 2 and 3 terminating into 4 at about apical 0.15; elytral explanate margin narrow, lacking prominent fringe setae. Metasternal glabrous area slightly wider than long (length: width as 18: 21), rhomboidal, subtabelliform, anteriorly attaining mesosternal intercoxal process as very short carina, moderately coarsely sparsely punctate posteriorly on disc, finely sparsely punctate anteriorly. Abdominal ventrites 1 – 3 and minutely basally 4 with hydrofuge pubescence. Females have the explanate elytral margin and the labrum similar to males. Aedeagus (Fig. 61): Length of main­piece 0.26 mm, length to tip of parameres 0.30 mm; lobes moderately long, apically weakly arcuate in ventral aspect, truncate in oblique aspect, not barbed; notches U­shaped, nearly parallel­sided, ca. 2 x width of lobes, dorsal deeper than ventral; duct nearly straight, not expanded apically; apical paramere seta moderately elongate, ca. 2 x length of next longest seta.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF96FFABFEC7793269BEF47E.taxon	etymology	Etymology. Named in reference to the shape of the metasternal glabrous area.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF96FFABFEC7793269BEF47E.taxon	distribution	Distribution. Currently known only from in and near the Finke Gorge National Park in southern Northern Territory (Fig. 74).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF7FFC5FEC77E4269D4F5AE.taxon	description	(Figures 17, 18, 93)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF7FFC5FEC77E4269D4F5AE.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: Cygnet R. Turkey Lane, 35 ° 46 ' S, 137 ° 10 ' E, 23 June 1994, Aust. water quality centre 3710. Deposited in the SAMA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF7FFC5FEC77E4269D4F5AE.taxon	diagnosis	Differential Diagnosis. Recognized by the narrow and transversely convex, semicylindrical, body form, the bisinuate margins of the lateral depressed areas of the pronotum, the large, serially closely spaced elytral punctures, and the black color. This species shows some resemblance to G. wattsi, but is distinguished there from by the larger size (ca. 1.86 v. 1.75), the more convex body form, the non­confluent pronotal foveae, the bisinuate lateral margins of the pronotum, and the coarser punctation. The male genitalia of the two species also suggest a relationship, but differ significantly in the shape and size of the duct, the shape of the lobes, the length and shape of the parameres, and form of the paramere setae (Figs. 16, 18).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF7FFC5FEC77E4269D4F5AE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.86 / 0.75; head 0.37 / 0.48; pronotum 0.41 / 0.65; elytra 1.30 / 0.75. Form elongate, narrow, transversely convex, especially elytra. Color black, dorsum strongly punctate, interpunctal surfaces strongly shining. Head shiny, frons moderately densely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, moderately densely punctate; pubescence very sparse on disc, more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum length: width 5: 14, anterior margin arcuate, without apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum straight in midregion; each lateral depression with posterior angle acute, lateral margin emarginate before posterior angle, with fringe of short setae; lateral fossulae shiny, deep, finely sparsely punctate; pronotal disc moderately convex, reliefs shiny, densely moderately coarsely punctate, each puncture with a recumbent seta; punctures absent between anterior and posterior foveae; median groove deep, moderately wide, extending nearly to margins, tapering at ends; anterior foveae oval, each separated from posterior fovea by about length of anterior fovea; posterior foveae oblique, deep, 1 / 2 as long as and twice as wide as median groove; posterolateral angles lacking impressions. Elytra nearly parallel­sided in anterior 0.5, transversely convex on disc, with six rows of punctures in shallow striae between suture and humeri; punctures round, small, serially separated from each other by less than puncture width, each with a recumbent seta; intervals shiny, weakly rounded, width 1.5 – 2.0 x that of punctures; posterior declivity gradual, summit slightly behind midlength; striae 2 and 3 terminating into 4 at about apical 0.15; elytral explanate margin very narrow, without distinct fringe of setae. Metasternal glabrous area slightly longer than wide, suboval, shining. Abdominal ventrites 1 – 3 and basal part of 4 with hydrofuge pubescence. Aedeagus (Fig. 18): Length of main­piece 0.31 mm, length to tip of parameres 0.35 mm; lobes very long, in ventral aspect apically blunt with lateral angles pointed, not barbed; ventral notch U­shaped, narrowing slightly apically, dorsal notch U­shaped, not as deep as ventral notch; duct roundly expanded at tip which is subequal width of lobes; paramere tips slightly angulate on medial surface; apical paramere seta elongate, ca. 2 x length of next longest seta, both of which are relatively thickened. Females unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF7FFC5FEC77E4269D4F5AE.taxon	etymology	Etymology. Named in reference to the body form.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF7FFC5FEC77E4269D4F5AE.taxon	distribution	Distribution. Currently known only from the type locality, Cygnet River, Kangaroo Island, South Australia (Fig. 93).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC5FFFAFEC77C126E7BF11E.taxon	description	(Figures 3, 4, 75, 94 – 97)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC5FFFAFEC77C126E7BF11E.taxon	materials_examined	Type Material. Holotype (male): Australia: Victoria: Narracan Falls, 4.1 km NE Thorpdale, on mud at edge of stream flowing through pasture, elev. 190 m, 38 ° 16 ' S, 146 ° 13 ' E, 4 February 1999, N. Porch (NP 27). Deposited in the ANIC. Paratypes (851): Australia: Australian Capital Territory: Black Mtn., light trap, 35 ° 16 ' S, 149 ° 6 ' E, 25 March 1968, M. S. Upton (1 ANIC); Canberra, stream entering L. Burley­Griffin, 35 ° 18 ' S, 149 ° 7 ' E, 30 March 1965, M. E. Bacchus (MEB 221) (3 BMNH); Paddy's River, 1 mi. S of Cotter Dam, 35 ° 29 ' S, 148 ° 59 ' E, 17 April 1969, S. Misko (1 ANIC); Paddy's River, nr. Murray's Corner, 35 ° 25 ' S, 148 ° 57 ' E, 3 April 1965, M. E. Bacchus (MEB 231) (1 BMNH); Paddy's River, 35 ° 29 ' S, 148 ° 59 ' E, 16 January 1969, J. Balfour­Browne (1 BMNH); Uriarra Crossing on Murrumbidgee River, quartz gravel and ' micro' mudflats at receding edge of large flowing river, elev. 445 m, 35 ° 14 ' S, 148 ° 57 ' E, 14 October 2000, N. Porch (NP 18) (20 ANIC); Wombat Creek, 6 km NE of Piccadilly Circus, flight intercept window / trough trap, elev. 750 m, 35 ° 19 ' S, 148 ° 51 ' E, 1 – 30 October 1985, Weir, Lawrence, Johnson (1 ANIC); New South Wales: Bemboka River at Greens Crossing, 1 km N of Bemboka, gravel and sand of small sandbank at edge of river, elev. 195 m, 36 ° 37 ' S, 149 ° 34 ' E, 9 April 2000, N. Porch (NP 28) (2 ANIC); Hunter River, Moonan Flat, 31 ° 55 ' S, 151 ° 14 ' E, 6 December 2002, A. Glaister (1 SAMA); Khancoban Creek, Khancoban, elev. 304.8 m, 36 ° 9 ' S, 148 ° 12 ' E, 1 April 1965, M. E. Bacchus (MEB 230) (1 BMNH); Nepean River, 33 ° 43 ' S, 150 ° 39 ' E, 7 September 1929, H. J. Carter (2 AMSA, 2 UQIC); nr. Sydney, Beecroft, 33 ° 44 ' S, 151 ° 3 ' E, 26 March 1965, M. E. Bacchus (MEB 215) (16 BMNH); Prospect ­ St. Mary's Road, 33 ° 47 ' S, 150 ° 55 ' E, 24 March 1965, M. E. Bacchus (MEB 212) (5 BMNH); Shaw Creek, c. 8 m., Springwood­Richmond Rd., 33 ° 38 ' S, 150 ° 38 ' E, 24 March 1965, M. E. Bacchus (MEB 214) (5 BMNH); Sydney, 33 ° 52 ' S, 151 ° 12 ' E, E. W. Ferguson Collection (2 ANIC); Queensland: Beechmont, 28 ° 7 ' S, 153 ° 10 ' E, 27 March 1932, Wassell (1 MCZ); Kilcoy, 11 km E, in creek debris, 26 ° 56 ', 152 ° 40 ' E, 19 October 1991, T. Gush (2 ANIC); Moran's Creek, SW of O'Reilly's Rainforest Guesthouse, Lamington NP, ca. 80 km S Brisbane [beeline], 28 ° 14 ’ 11.2 ” S 153 ° 08 ’ 01.1 ” E – 28 ° 13 ’ 59 ” S 153 ° 07 ’ 27 ” E, River (Moran's Creek), ca. 2 – 4 m wide, through dense rain forest, Eucalypt forest and open grassland, 760 – 820 m a. s. l., M. A. Jäch (AU 9) (1 NMW); Mt. Nebo Road, SE Mt. Nebo, ca. 540 m a. s. l., ca. 30 km NE Brisbane [beeline], 27 ° 24 ' 08 S' ' 152 ° 48 ' 00 '' E, Pond, ca. 200 m, Sclerophyll forest, 21 August 2004, M. A. Jäch (AU 1) (8 NMW); N. Q., Bushy Creek, Mossman ­ Mt. Lewis Rd., elev. 365.76 m, 16 ° 37 ' S, 145 ° 21 ' E, 30 – 31 October 1966, E. Britton (1 ANIC); Oxley Creek, 27 ° 32 ' S, 153 ° 0 ' E, 2 July 1932, Wassell (1 UQIC); Running Creek, along road between Mt. Chinghee NP and Border Ranges NP, at Seventh Bridge, ca. 40 km [beeline] S Beaudesert, 28 ° 19 ’ 13.2 ” S 152 ° 55 ’ 39.1 ” E, River (Running Creek), ca. 5 – 8 m wide, incl. rockpools, through open forest (Casuarina, Eucalypt), 25 August 2004, M. A. Jäch (AU 13) (10 NMW); Stream, at Cedar Creek Road, above Cedar Creek Falls, below Eagle Heights, ca. 40 km SSE Brisbane [beeline], 27 ° 53 ’ 50.0 ” S 153 ° 10 ’ 49.3 ” E, ca. 4 m wide, riffles, boulders, rock pools, sand margins, through forest, 22 August 2004, M. A. Jäch (AU 5) (10 NMW); Tasmania: Creekton Rivulet, 2 km S of Strathblane, thick weedy litter and organic mud at edge of small pool of creek in dry sclerophyll forest / scrub, elev. 10 m, 43 ° 21 ' S, 146 ° 58 ' E, 19 February 2000, N. Porch (20) (56 ANIC); Frankford [no date], 41 ° 20 ' S, 146 ° 46 ' E, Lea (1 MVMA); Junee River, 0.2 km downstream of Junee Cave, sandy mud at bottom of riverbank in regrowth rainforest / wet sclerophyll forest, elev. 300 m, 42 ° 34 ' S, 146 ° 36 ' E, 18 February 2000, N. Porch (2) (22 ANIC); Little Piper River at bridge on B 82, sandy litter at edge of river in scrubby forest, elev. 15 m, 41 ° 2 ' S, 147 ° 14 ' E, 12 February 2000, N. Porch (3) (16 ANIC); Mount, creek Barrow, inundation debris, 41 ° 22 ' S, 147 ° 21 ' E, 8 December 1982, Endrödy­Younga (AU­ 101) (14 TMSA); Pipers Brook at B 82 bridge, 2.7 km NW of Pipers Brook, muddy litter at edge of small pools of perrenial creek, elev. 50 m, 41 ° 3 ' S, 147 ° 10 ' E, 12 February 2000, N. Porch (17) (51 ANIC); Polleys Creek, just S of Chinamans Corner on Mathinna Plains Road, coarse gravel at edge of small creek at road edge; rainforest, elev. 780 m, 41 ° 22 ' S, 147 ° 36 ' E, 13 February 2000, N. Porch (1) (3 ANIC); St Patric Riv. Targa, inundation debris, 41 ° 18 ' S, 147 ° 21 ' E, 8 December 1982, Endrödy­Younga (AU­ 104) (14 TMSA); Victoria: 1 km N Possum Hollow, W. br. Tarwin River, 4.6 km SSW Allambee, ex shaded silty mud at edge of small ' creek' at pasture­wet sclerophyll forest boundary, elev. 240 m, 38 ° 18 ' S, 146 ° 1 ' E, 14 January 1999, N. Porch (NP 19) (19 ANIC); 10 km NE Mirranatwa, small creek bed ­ drying pool, stony, dead leaves, dry sclerophyll forest, 37 ° 36 ' S, 142 ° 13 ' E, 12 October 1997, C. Watts (1 SAMA); Brisbane Ranges National Park, 8.2 km W Rowsley Trig., litter and mud at edge of small firedam in dry sclerophyll forest, elev. 405 m, 37 ° 44 ' S, 144 ° 16 ' E, 1 January 2000, N. Porch (60) (10 ANIC); Bullock Creek, at Forest Road, 13 km N of Longwarry, gravel and litter at edge of small shaded forest stream flowing through wet sclerophyll forest, elev. 135 m, 37 ° 58 ' S, 145 ° 49 ' E, 1 January 2003, N. Porch (79) (2 ANIC); Bunyip R. at Princes Highway, amongst willow roots and on sand at edge of river under thick willow cover in pasture, elev. 40 m, 38 ° 5 ' S, 145 ° 45 ' E, 15 January 1999, N. Porch (NP 22) (6 ANIC); Dandenong Creek at Brady Road, Dandenong North, mud at edge of artificial dam in pasture, elev. 30 m, 37 ° 57 ' S, 145 ° 13 ' E, 28 September 1999, N. Porch (53) (14 ANIC); Elizabeth Ck., 1.2 km S Childers, very abundant in sandy mud and wet litter (80 cm by 20 cm) along edge of small forest creek in wet sclerophyll forest (Eucalyptus regnans), elev. 195 m, 38 ° 19 ' S, 146 ° 6 ' E, 28 October 1998, N. Porch (NP 09) (4 ANIC); Elizabeth Ck., 1.5 km N Allambee South, mud at edge of creek flowing under shady willows, elev. 125 m, 38 ° 20 ' S, 146 ° 7 ' E, 11 September 1998, N. Porch (NP 05) (10 ANIC); Franklin River at South Gippsland Highway, on and in shaded silty mud at edge of small ' creek' in pasture, elev. 10 m, 38 ° 39 ' S, 146 ° 18 ' E, 13 January 1999, N. Porch (NP 14) (3 ANIC); Genoa River at Genoa, u / s of old highway bridge, gravel at edge of small river flowing through pasture, elev. 10 m, 37 ° 28 ' S, 149 ° 35 ' E, 10 April 2000, N. Porch (NP 25) (1 ANIC); Healesville, Dandenong Ranges, 37 ° 39 ' S, 145 ° 32 ' E, 1 – 30 October 1968, C. Watts (3 SAMA); Holey Plains State Park, firedam on Crooke Track, fine sand and organics at the edge of a small firedam in dry sclerophyll forest, elev. 45 m, 38 ° 10 ' S, 146 ° 20 ' E, 16 April 2002, N. Porch (87) (7 ANIC); Kangaroo Ck. on Springhill Rd., 5.8 km E Glenlyon, sandy mud along edge of creek (perennial) pools, elev. 510 m, 37 ° 18 ' S, 144 ° 18 ' E, 31 January 1999, N. Porch (NP 24) (132 ANIC); LaTrobe R., Rosedale, 38 ° 9 ' S, 146 ° 34 ' E, 9 December 1978, not given (2 MVMA); Latrobe River at Piedmont, gravel at edge of river at pasture / forest boundary, elev. 255 m, 37 ° 53 ' S, 145 ° 54 ' E, 1 January 2003, N. Porch & N. Krause (NP 54) (5 ANIC); Little Morwell River, 3.8 km NNE Mirboo North, sandy mud and litter accumulation at edge of small creek; dry / moist riparian sclerophyll forest, elev. 165 m, 38 ° 22 ' S, 146 ° 10 ' E, 3 October 1999, N. Porch (NP 45) (1 ANIC); same locality, elev. 165 m, 38 ° 22 ' S, 146 ° 10 ' E, 24 February 2001, N. Porch & Latrobe Valley Field Naturalists (LVFN) (NP 10) (2 ANIC); Little Morwell River, at Ricardo Road, Darlimurla, litter and mud at edge of small creek in dry sclerophyll forest, elev. 150 m, 38 ° 22 ' S, 146 ° 12 ' E, 9 April 2000, N. Porch (NP 49) (6 ANIC); Little River at Bacchus Marsh­Geelong Road, sandy gravel and muddy sand at edge of still pool of perrenial creek in riparian forest remnants, elev. 105 m, 37 ° 50 ' S, 144 ° 23 ' E, 20 October 1999, N. Porch (36) (5 ANIC); Loddon Falls, base of, NE of Glenlyon, sandy gravel at edge of waterfall splashpool in scrubby gorge, elev. 470 m, 37 ° 16 ' S, 144 ° 14 ' E, 16 March 2001, N. Porch & K. Sniderman (19) (24 ANIC); Macalister­Thomson River Jn, NMV Survey Dept. GRES T 26 no. 1, 37 ° 46 ' S, 146 ° 40 ' E, 5 December 1976, not given (1 MVMA); Mitta Mitta River, 8 km NW of Dartmouth Dam, 36 ° 30 ' S, 147 ° 26 ' E, 5 November 1976, A. A. Calder (1 MVMA); Morwell River, 6.1 km SSE Boolarra on Morwell River Road (Apex Park), willow roots and sandy mud / gravelly mud at edge of small river; under weeping willows, elev. 115 m, 38 ° 25 ' S, 146 ° 18 ' E, 29 November 1999, N. Porch (NP 38) (5 ANIC); Morwell River on Driffield ­ Yinnar Rd., S 43, LaTrobe C. Survey, 38 ° 19 ' S, 146 ° 19 ' E, 6 December 1978 (3 MVMA); Narracan Ck. at Cooks Rd., 2.3 km NW Thorpdale, in gravel at edge of gravelly riffle of small creek flowing through pasture, elev. 135 m, 38 ° 16 ' S, 146 ° 10 ' E, 4 February 1999, N. Porch (NP 28) (1 ANIC); Narracan Falls, 4.1 km NE Thorpdale, on mud at edge of stream flowing through pasture, elev. 190 m, 38 ° 16 ' S, 146 ° 13 ' E, 4 February 1999, N. Porch (NP 27) (11 ANIC); Sailors Falls, base of, S. of Daylesford, gravelly and sandy margins of pools immediately d / s of waterfall, elev. 590 m, 37 ° 23 ' S, 144 ° 7 ' E, 16 March 2001, N. Porch & K. Sniderman (14) (92 ANIC); Settling Pods Dam, at Junction of Settling Ponds Tk. & Hudbrick Tk., gravelly mud at edge of small dam in dry sclerophyll forest, elev. 260 m, 37 ° 7 ' S, 143 ° 40 ' E, 9 June 2001, N. Porch (74) (1 ANIC); Simpson Ck, 12 km SW Orbost, 27 ° 47 ' S, 148 ° 20 ' E, 16 January 1997, C. Watts (2 SAMA); Spargo Creek, W. of, firedam nr Centre Track, clayey mud at edge of small firedam in pine forest, elev. 705 m, 37 ° 27 ' S, 144 ° 5 ' E, 17 February 2002, N. Porch (92) (1 ANIC); Tarago River, Bellbird Park at old Princes Highway, ex sandy mud and litter in sun along edge of slow flowing river in pasture, elev. 50 m, 38 ° 5 ' S, 145 ° 48 ' E, 15 January 1999, N. Porch (NP 21) (50 ANIC); Toomuc Ck., at Princes Highway, Pakenham, on silty sand and sand along margins of gravelly ' semiurban' creek, elev. 45 m, 38 ° 4 ' S, 145 ° 28 ' E, 4 February 1999, N. Porch (NP 26) (50 ANIC); Werribee River, 11.5 km NNW Ballan, 37 ° 45 ' S, 144 ° 34 ' E, 22 April 1982, A. J. Boulton (1 ANIC); Woori Yallock Ck., at Warburton Highway, ex muddy margins of undercut creek banks near water level; pasture, elev. 110 m, 37 ° 47 ' S, 145 ° 31 ' E, 23 February 1999, N. Porch (NP 35) (88 ANIC); Yarra River at Launching Place, margin of Yarra River on silty fine sand, elev. 115 m, 37 ° 47 ' S, 145 ° 35 ' E, 23 February 1999, N. Porch (NP 36) (12 ANIC). Representative specimens to be deposited in CMNH, FMNH, MCZ, NPC, QMBA, and USNM.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC5FFFAFEC77C126E7BF11E.taxon	diagnosis	Differential Diagnosis. Recognized by the distinctive fringe of setae on the elytral margin, the finely sparsely punctate pronotum, the narrow median groove and nonmicroreticulate foveae, and the elytral intervals wider than the serial punctures. Very similar in dorsal habitus to G. australis (which see), but elytra generally more strongly punctate and have the setae on the intervals more prominent, erect, especially developed on sides and over posterior declivity. Reliable determinations, especially of abraded specimens, will be based on study of the male genitalia, which are similar in being strongly barbed, but differ in shapes of the lobes and especially the shape of the duct, which in G. setosus is long, nearly straight and nearly parallel­sided, and has a rounded apex (Figs. 2, 4).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC5FFFAFEC77C126E7BF11E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.97 / 0.86; head 0.37 / 0.48; pronotum 0.44 / 0.67; elytra 1.26 / 0.86. Form moderately ovate, moderately convex. Color brown, head darker, dorsal reliefs shining. Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal midlongitudinal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate; pubescence sparse but rather long on disc, shorter but denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length; anterior margin arcuate, with low upturned apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; arcuate setae, originating from basal sides of pronotum, on top of lateral hyaline border; anterior margin of pronotum slightly arcuate in midregion; each lateral depression with posterior in form of right angle, lateral margin distinctly setose; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, extremely finely sparsely punctate, each puncture with a recumbent yellow seta; median groove shallow, narrow, extending nearly to margins, tapering at ends; anterior foveae well developed, slightly elongate; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and as wide as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, sides nearly vertical in basal 0.5, with six rows of slightly elongate, closely spaced punctures between suture and humeri; each puncture with a decumbent seta that overlaps base of following seta; intervals flat or slightly rounded, width 1.5 – 2.0 x that of punctures; intervals with sparse, erect, moderately long setae, especially developed on sides and over posterior declivity; summit of declivity near posterior 0.66, where elytra are transversely markedly convex; elytral explanate margin very narrow, with fringe of long setae. Metasternal glabrous area length equal width, oval, convex, shining, with a few punctures. Abdominal ventrites 1 – 3 and minutely basally 4 with hydrofuge pubescence. Aedeagus (Fig. 4): Length of main­piece 0.30 mm, length to tip of parameres 0.31 mm; lobes relatively long, in ventral aspect apical width subequal paramere width, each lobe with strong barb near midlength; notches U­shaped, ventral notch slightly deeper and slightly narrower than dorsal notch; ventral notch narrowest width greater than greatest width of lobes; duct rather elongate, nearly parallel­sided, apex slightly enlarged, round in ventral aspect; apical paramere seta elongate, ca. 2 x length of next longest seta. Females have the explanate elytral margin similar to males; the labrum has a very small apicomedian tooth, smaller than that of males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC5FFFAFEC77C126E7BF11E.taxon	etymology	Etymology. Named to reflect the more prominently setose condition — when compared to members of the similar G. australis.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFC5FFFAFEC77C126E7BF11E.taxon	distribution	Distribution. Widely distributed, especially prevalent in eastern ranges, from Victoria to Queensland and on Tasmania (Fig. 75). Currently not known from South Australia.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEFFFDDFEC77E426AB7F5DE.taxon	materials_examined	Type Material. Holotype (male): Australia: Western Australia: Murchison R., 27 ° 49 ' S, 114 ° 41 ' E, 28 March 1971, E. F. Riek. Deposited in the ANIC. Paratypes: Same data as holotype (32 ANIC). Representative specimens to be deposited in MCZ, NPC, SAMA, and WAMP.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEFFFDDFEC77E426AB7F5DE.taxon	diagnosis	Differential Diagnosis. Recognized by the elongate body form and legs, the large and deep pronotal foveae, the shining dorsal reliefs, and the striate­impressed elytral series. Females have the explanate elytral margin about twice as wide as it is in males, and markedly arcuate. Most similar in dorsal habitus to G. coruscus (Figs. 44, 48), but the male genitalia of the two species differ markedly in shape of the main­piece and in paramere setae (Figs. 45, 49).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEFFFDDFEC77E426AB7F5DE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 2.04 / 0.82; head 0.37 / 0.52; pronotum 0.48 / 0.67; elytra 1.30 / 0.82. Form moderately ovate, moderately convex. Color light brown to testaceous, head darker, dorsal reliefs shining. Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 x apical width, very sparsely punctate apically, more coarsely punctate basally; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum length: width as 5: 13, moderately pubescent, anterior margin arcuate, with prominent apicomedian upturned tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum nearly straight in midregion; each lateral depression with posterior angle obtuse, lateral margin arcuate from anterior angles, then emarginate in front of posterior angle, sparsely setose; lateral fossulae deep, terminating anteriorly in pit, very effacedly microreticulate; pronotal disc moderately convex, sparsely moderately finely punctate, most punctures without discernible setae; median groove moderately deep and wide, not attaining margins, tapering at ends; anterior foveae well developed; posterior foveae oblique, linear impressions slightly greater than 1 / 2 as long as and slightly wider than median groove; posterolateral angles with indistinct shallow impressions. Elytra weakly convex on disc, with six rows of closely spaced punctures in well developed striae between suture and humeri, each puncture with short inconspicuous seta; intervals rounded, width equal that of punctures; posterior declivity gradual, summit slightly behind midlength; striae 2 and 3 terminating into 4 at about apical 0.15; elytral margin very narrow, lacking prominent setae. Metasternal glabrous area longer than wide (as 19: 14), elongate oval, shining, convex. Abdominal ventrites 1 – 3 and basal part of 4 with hydrofuge pubescence. Aedeagus (Fig. 49): Length of main­piece 0.39 mm, length to tip of parameres 0.46 mm; lobes relatively short, strongly barbed; apical paramere seta much longer than other setae. Females have the explanate elytral margin markedly arcuate, about twice as wide as it is in males, widest slightly in front of midlength, slightly wider than the mesotibia; the anterior margin of the labrum is weakly apicomedially emarginate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEFFFDDFEC77E426AB7F5DE.taxon	etymology	Etymology. Named in reference to the sexually dimorphic explanate margins of the elytra.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEFFFDDFEC77E426AB7F5DE.taxon	distribution	Distribution. Currently known only from the type locality in far western Western Australia (Fig. 73).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9DFFAFFEC77EE26959F3B6.taxon	materials_examined	Type Material. Holotype (male): Australia: Queensland: N. Q., 15 km NE Mareeba, MDPI intercept trap site No. 25, flight intercept trap, 16 ° 56 ' S, 145 ° 32 ' E, 20 December 1984 – 7 January 1985, Storey & Titmarsh. Deposited in the QMBA. Paratypes (10): Australia: Northern Territory: 30 km N of Wauchope, 20 ° 22 ' S, 134 ° 14 ' E, 13 October 1972, M. S. Upton (1 ANIC); Butterfly Gorge Nature Pk Douglas River, at light, 13 ° 45 ' S, 131 ° 34 ' E, 19 July 1994, T. Weir & A. Roach (1 ANIC); Queensland: 5 km S Batavia Downs, flight intercept trap, 12 ° 41 ', 142 ° 41 ' E, 23 August – 16 September 1992, P. Zborowski & L. Miller (2 ANIC); Hann River, 15 ° 11 ' S, 143 ° 52 ' E, 16 August 1992, P. Zborowski & J. Cardale (1 ANIC); Leichart Creek, 8 k N Bluewater, 19 ° 10 ' S, 146 ° 32 ' E, 18 December 2002, A. J. & C. H. S. Watts (2 SAMA); Western Australia: 14 km SbyE Kalumburu Mission, CALM Site 4 / 3 [Western Australian Department of Conservation and Land Management], at light, open forest, 14 ° 25 ' S, 126 ° 40 ' E, 3 – 6 June 1988, T. A. Weir (2 ANIC); Synnot Ck., CALM Site 25 / 1 [Western Australian Department of Conservation and Land Management], at light, open forest, 16 ° 31 ' S, 125 ° 16 ' E, 17 – 20 June 1988, T. A. Weir (1 ANIC). Representative specimens to be deposited in MCZ and NPC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9DFFAFFEC77EE26959F3B6.taxon	diagnosis	Differential Diagnosis. A very distinctive species, recognized by the small size, the squamiform dorsal setae, and the wide fringe of arcuate setae on the elytral lateral margins (Fig. 66). Similar to G. nanosetus (Fig. 64) in having the abdominal hydrofuge pubescence reduced to the first two ventrites, but differing in smaller size, more distinctly widened (squamiform) dorsal setae, wider fringe of setae on the elytral margins, larger elytral punctures, confluent anterior­posterior pronotal foveae, and the reduced abdominal hydrofuge pubescence, covering ventrite 1 and present basolaterally on ventrite 2. The male genitalia of the two species are quite dissimilar (Figs. 65, 67).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9DFFAFFEC77EE26959F3B6.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.26 / 0.56; head 0.30 / 0.37; pronotum 0.30 / 0.48; elytra 0.82 / 0.56. Form moderately ovate, moderately convex. Dorsum dark brown, weakly shining beneath distinctive whitish or yellowish setae. Head with dorsum clothed in distinctive decumbent setae, setal sockets minutely raised; frons very sparsely punctate; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength about 0.5 apical width, non­punctate (but setal sockets minutely raised). Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum at angle to clypeus, only very small apicomedian tooth visible in habitus view; width twice length. Maxillary palpomere 3 about twice length of 4. Pronotum distinctively setose; lateral hyaline border well developed, origin at base of lateral depression, lateral margin angulate, then continuous with very narrow posterior hyaline border; anterior margin of pronotum arcuate between lateral depressions; each lateral depression with posterior angle acute, lateral margin straight, densely clothed in long setae which form a fringe equal to 0.5 width of lateral depression; lateral fossulae deep; pronotal disc moderately convex, with short flattened narrow setae that taper from base to apex; median groove narrow, deeper in front and behind midlength, constricted in midlength, not attaining anterior and posterior margins, tapering at ends; anterior foveae well developed, transverse; posterior foveae oblique, shallow, oval, nearly attaining anterior foveae; posterolateral angles lacking impressions. Elytra clothed in distinctive decumbent flattened setae that taper from base to apex; setae serial, forming six rows between suture and humeral angle; punctures on disc large, transverse, obliterating intervals; elytra convex on disc; summit of posterior declivity at about midlength; elytral explanate margin very narrow, with fringe of long arcuate setae, those in anterior 0.5 of elytron twice as long as pronotal fringe. Metasternal glabrous area length less than width (as 10: 12), subrhomboidal, shining, convex. Abdominal ventrites 1 and basolaterally 2 with hydrofuge pubescence. Aedeagus (Fig. 67): Length of main­piece 0.20 mm, length to tip of parameres 0.21 mm; lobes relatively short, weakly subapically barbed; apical paramere seta longer than other setae. Females unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9DFFAFFEC77EE26959F3B6.taxon	etymology	Etymology. Named in reference to the widened and flattened dorsal setae.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF9DFFAFFEC77EE26959F3B6.taxon	distribution	Distribution. A wide northern distribution pattern, found north of about 20 ° S. latitude, with widely separated locality records in Western Australia, Northern Territory, and Queensland (Fig. 74).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF93FFA1FEC77B3A69C1F176.taxon	materials_examined	Type Material. Holotype (male): Australia: South Australia: Dalhousie Springs, damp litter near hot springs, FMHD # 83 ­ 677, 26 ° 27 ' S, 135 ° 28 ' E, 30 May 1983, L. E. Watrous. Deposited in the ANIC. Paratypes: Same data as holotype (2 ANIC).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF93FFA1FEC77B3A69C1F176.taxon	diagnosis	Differential Diagnosis. Recognized by the piceous color, the pronotal lateral margin produced in an obtuse point slightly anterior to midlength, the pronotal disc densely moderately coarsely punctate, the elytral series subsulcately impressed, and the elytral explanate margin narrow, with a short fringe of setae. The elytra and the male genitalia distinctly differ from that of other species (Figs. 54, 55).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF93FFA1FEC77B3A69C1F176.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.89 / 0.78; head 0.33 / 0.48; pronotum 0.44 / 0.67; elytra 1.11 / 0.78. Form moderately ovate, moderately convex. Color piceous, palpi and tarsi lighter, dorsum moderately shining. Frons reliefs moderately punctate, sparsely pubescent; interocular foveae deep, continuing to posterior margin of head; interocular tuberculi very small, circular, located midway between midline and margin of eye; posterior area behind interocular tuberculi depressed from side to side; frons depressions effacedly microreticulate; Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, moderately coarsely and densely punctate, dull; pubescence very sparse on disc, more developed later­ ally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum length: width as 5: 13, anterior margin arcuate, with very low apicomedian upturned tooth, oval depression behind tooth. Maxillary palpomere 3 about four times length of 4. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum nearly straight in midregion, shallowly emarginate behind eye; each lateral depression with posterior angle produced to acute point, lateral margin setose, distinctly produced to an obtuse point slightly anterior to midlength; lateral fossulae deep, effacedly microreticulate, as are other foveae; pronotal disc moderately convex, moderately coarsely punctate, each puncture with a recumbent yellow seta which contrasts with dark cuticle; median groove moderately deep, narrow, extending nearly to margins, tapering at ends; anterior foveae well developed; posterior foveae oblique, linear impressions 1 / 2 as long as and slightly wider than median groove; posterolateral angles without impressions. Elytra moderately convex on disc, with six rows of punctures in well developed striae between suture and humeri; intervals slightly raised, subsulcate, width 1.5 – 3.0 x that of punctures, each interval with unilinear row of short decumbent setae each of which attains base of following seta, punctures round, separated from each other by about puncture width; summit of declivity slightly behind midlength; striae 2 and 3 terminating into 4 at about apical 1 / 4; explanate margin narrow, with short fringe of setae about 0.5 length of pronotal fringe. Metasternal glabrous area length equal width, oval, shining, convex. Abdominal ventrites 1 – 3 and laterally 4 with hydrofuge pubescence. Aedeagus (Fig. 55): Length of main­piece 0.28 mm, length to tip of parameres 0.31 mm; lobes relatively long, tapering, each lobe with a small barb basally and slightly bent apically; notch U­shaped, nearly parallel­sided; duct with cuticular crease at apex; apical paramere seta elongate, much longer than other apical setae but subequal length of more proximal setae; main­piece widened near midlength. Females have the elytral explanate margin slightly wider than that of males; the labrum has a transverse oval subapicomedian depression like that of males, but lacks an apicomedian tooth.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF93FFA1FEC77B3A69C1F176.taxon	etymology	Etymology. Named in reference to the subsulcate elytra.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FF93FFA1FEC77B3A69C1F176.taxon	distribution	Distribution. Currently known only from the type locality, Dalhousie Springs in northern South Australia (Fig. 86).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE6FFDAFEC77D276E57F47E.taxon	materials_examined	Type Material. Lectotype (hereby designated; female): Australia: New South Wales: Sydney [labels: " North Sydney flood refuse 9.06 HJC "; " Type T­ 4192 "]. Deposited in the MVMA. The type series in the Museum of Victoria consists of two female specimens. I have selected one specimen to serve as lectotype and have affixed a label indicating such. In the second specimen the pronotal foveae are longitudinally, broadly confluent, whereas in the lectotype there is only the faintest indication of a shallow depression linking the foveae.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE6FFDAFEC77D276E57F47E.taxon	diagnosis	Differential Diagnosis. Recognized from other species with dull dorsum and similar abdominal hydrofuge pubescence pattern (G. brisbanensis and G. fumosus) by the angulate lateral margins of the pronotum, the black color, and the more distinctly striate­impressed elytral series (Figs. 35, 37, 39). Males are unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE6FFDAFEC77D276E57F47E.taxon	description	Description. Size (length / width, mm) lectotype: body (length to elytral apices): 1.56 / 0.72; head 0.32 / 0.44; pronotum 0.40 / 0.60; elytra 1.00 / 0.72. Form moderately ovate, moderately convex. Color black, entire dorsal surface dull. Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 x apical width, very sparsely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length, anterior margin broadly and shallowly emarginate, almost straight. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression with posterior angle produced as acute point, lateral margin setose, distinctly produced to an obtuse point slightly anterior to midlength; lateral fossulae deep, microsculpture similar to remainder of pronotum; pronotal disc moderately convex, extremely finely sparsely punctate, each puncture with a recumbent yellow seta which contrasts with black cuticle; median groove shallow, very narrow, extending nearly to margins, tapering at ends; anterior foveae well developed; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and twice as wide as median groove; posterolateral angles each with shallow impression. Elytra moderately convex on disc, with six rows of punctures in well developed striae between suture and humeri; punctures round, separated from each other by about puncture width; intervals rounded, width twice that of punctures; summit of declivity slightly behind midlength; striae 2 and 3 terminating into 4 at about apical 1 / 4; elytral margin lacking prominent setae. Prosternum lacking midlongitudinal carina. Metasternal glabrous area large, dull similar to pronotum. Abdominal ventrites 1 – 3 and anterior 0.33 of 4 with hydrofuge pubescence; other sterna dull, lacking hydrofuge pubescence. Aedeagus: Male unknown.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFE6FFDAFEC77D276E57F47E.taxon	distribution	Distribution. Although described more than seventy years ago, this species is still known only from the two female type specimens, collected in " north Sydney " (Fig. 84).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFEFFD2FEC77EE26E7AF22E.taxon	materials_examined	Type Material. Holotype (male): Australia: Victoria: Victorian Alps [no date], Blackburn. Deposited in the SAMA. Paratypes (23): Australia: Australian Capital Territory: Casuarina Sands on Murrumbidgee River, coarse sand, gravel and roots (Casuarina) at edge of riffle zone of large river; Casuarina riparian forest, elev. 475 m, 35 ° 19 ' S, 148 ° 57 ' E, 21 July 2000, N. Porch (NP 69) (1 ANIC); Kambah Pool, 35 ° 24 ' S, 149 ° 1 ' E, 26 November 1998, C. Watts (1 SAMA); Queensland: Albert River, ca. 30 m a. s. l., and Dunn Creek (residual pool in tributary of Albert River) at Alan Wilke Bridge, S of Wolfdene [or Wolffdene acc. to other sources], ca. 30 km SE Brisbane [beeline], 27 ° 46 ’ 34.7 ” S 153 ° 11 ’ 07.2 ” E, River (Albert River), ca. 20 m wide, slightly polluted, flowing through cultivated land, 21 August 2004, M. A. Jäch (AU 3) (12 NMW); Dayboro, 2 km S, in moist soil, dry river bed, 27 ° 13 ' S, 152 ° 50 ' E, 12 October 1991, T. Gush (1 ANIC); Kilcoy, 11 km E, in creek debris, 26 ° 56 ', 152 ° 40 ' E, 19 October 1991, T. Gush (7 ANIC); Running Creek, along road between Mt. Chinghee NP and Border Ranges NP, at Seventh Bridge, ca. 40 km [beeline] S Beaudesert, 28 ° 19 ’ 13.2 ” S 152 ° 55 ’ 39.1 ” E, River (Running Creek), ca. 5 – 8 m wide, incl. rockpools, through open forest (Casuarina, Eucalypt), 25 August 2004, M. A. Jäch (AU 13) (1 NMW). Representative specimens to be deposited in MCZ, NPC, and QMBA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFEFFD2FEC77EE26E7AF22E.taxon	diagnosis	Differential Diagnosis. Recognized by the very convex form, the shining dorsum, the finely sparsely punctate pronotum contrasting with the strongly punctate and striateimpressed elytral series, and especially the confluent pronotal anterior and posterior foveae, forming a narrow sinuate line on each side of the median groove. Distinguished from G. nicki, which is also quite convex dorsally, by the confluent pronotal foveae (Figs. 29, 31). The male genitalia of the two species show some similarity, both lacking barbs, but the parameres are much longer and stronger and the lobes more sharply pointed in G. trilineatus (Figs. 30, 32). Distinguished from G. bacchusi (Fig. 33), which also has confluent pronotal foveae, by the less transverse and more convex pronotum, the striateimpressed elytral punctures, the shorter setae of the elytral punctures, and the fringe of setae on the elytral lateral margins.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFEFFD2FEC77EE26E7AF22E.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.67 / 0.78; head 0.33 / 0.44; pronotum 0.44 / 0.57; elytra 1.07 / 0.78. Form moderately ovate, rather strongly convex. Color brown, head darker, dorsal reliefs highly shining. Frons very finely sparsely punctate, very sparsely pubescent on disc, more setose laterally; interocular foveae deep; interocular tuberculi distinct; basal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate; setae very sparse on disc, distinctly denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 3 x length; anterior margin arcuate, with very small apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate in midregion; each lateral depression with posterior angle acute point, lateral margin weakly arcuate, with short fringe of setae; lateral fossulae deep, lacking microsculpture; pronotal disc transversely quite convex, extremely finely sparsely punctate, most punctures with a minute recumbent seta; median groove deep, narrow, extending nearly to margins, tapering at ends; anterior and posterior foveae slightly narrower than median groove, joined by narrow channel to form slightly sinuate groove; posterolateral angles without shallow impressions. Elytra very convex on disc, with six rows of deep, slightly elongate, closely spaced punctures in shallow striae between suture and humeri; most punctures without a perceptible seta; intervals rounded, width 1.0 – 1.5 x that of punctures; even numbered intervals with widely spaced very short setae in unilinear row; summit of declivity slightly in front of midlength, where elytra are transversely markedly convex; explanate margin nearly nonexistent; margin with fringe of very short setae. Metasternal glabrous area length equal width, oval, shining, convex. Abdominal ventrites 1 – 3 with hydrofuge pubescence. Aedeagus (Fig. 30): Length of main­piece 0.30 mm, length to tip of parameres 0.36 mm; lobes relatively long, each tapering, not barbed; parameres widened and strong apically, setae stout. Females have the elytral explanate margin similar to that of males; the labrum anterior margin is arcuate, lacking the minute tooth present in males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFEFFD2FEC77EE26E7AF22E.taxon	etymology	Etymology. Named in reference to the three impressed lines on the pronotum.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFFEFFD2FEC77EE26E7AF22E.taxon	distribution	Distribution. Currently known from two widely disjunct areas, one each in the Australian Capital Territory and Queensland, and the type locality, " Victorian Alps " (Fig. 77).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCBFFF9FEC77C7A6AE0F2FE.taxon	description	(Figures 7, 8, 74)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCBFFF9FEC77C7A6AE0F2FE.taxon	materials_examined	Type Material. Holotype (male): Australia: Queensland: Cape York, Archer River, Archer Bend, moderately large shallow billabong / pool in otherwise dry river bed; unvegetated with thick layer of dead leaves etc., 13 ° 28 ' S, 142 ° 12 ' E, 28 September 1983, C. Watts. Deposited in the SAMA. Paratypes (23): Australia: Northern Territory: Kakadu NP, Malapanbanjo Ck, c. 8 km S of Arnhem Hwy on Pine Creek Rd., 12 ° 16 ' S, 132 ° 40 ' E, M. B. Malipatil (1 MAGD); Nourlangie Creek, 8 km. E of Mt. Cahill, mud at edge of waterhole, 12 ° 52 ' S, 132 ° 47 ' E, 27 October 1972, E. B. Britton (15 ANIC); Queensland: 10 km WNW of Rokeby (Mango Lagoon), lagoon with rocks at edge, 13 ° 38 ' S, 142 ° 35 ' E, 27 October 1992, P. Zborowski, T. Weir (2 ANIC); Cape York, Archer River, Archer Bend, moderately large shallow billabong / pool in otherwise dry river bed; unvegetated with thick layer of dead leaves etc., 13 ° 28 ' S, 142 ° 12 ' E, 28 September 1983, C. Watts (4 SAMA); Ling Creek, watersweep, 12 ° 19 ' S, 142 ° 10 ' E, 14 August 1993, P. Zborowski & J. Balderson (1 ANIC). Representative specimens to be deposited in MCZ and NPC.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCBFFF9FEC77C7A6AE0F2FE.taxon	diagnosis	Differential Diagnosis. Recognized by the truncate body form, the shining dorsum, the shallowly striate­impressed elytral series, the large, shining, subrhomboidal metasternal glabrous area, and the abdominal ventrites 1 – 2 and basally 3 with hydrofuge pubescence. The dorsal sculpture is somewhat similar to that of G. angulonotus, but the two species differ in body proportions and size (Figs. 5, 7). The male genitalia have two barbs on each lobe, as does G. levis, but the two species differ in most other genitalic characters and are so different externally as to defy comparison.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCBFFF9FEC77C7A6AE0F2FE.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.49 / 0.71; head 0.30 / 0.44; pronotum 0.33 / 0.59; elytra 0.94 / 0.71. Form moderately ovate, moderately convex. Color dark brown, legs lighter, dorsal reliefs moderately shining. Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal midlongitudinal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate; pubescence sparse on disc, denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length; anterior margin arcuate, with very low upturned apicomedian tooth. Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate in midregion; each lateral depression with posterior in form of right angle, lateral margin distinctly setose; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, extremely finely sparsely punctate, each puncture with a recumbent seta; median groove moderately deep, narrow, extending nearly to margins, tapering at ends; anterior foveae shallow, sides gradually sloping; posterior foveae oblique, shallow, linear impressions nearly 1 / 2 as long as and as wide as median groove, sides gradually sloping; posterolateral angles without impressions. Elytra convex on disc, with six rows of slightly elongate, closely spaced punctures in shallow striae between suture and humeri; each puncture with a decumbent seta that overlaps base of following seta; intervals slightly rounded, width 2 – 3 x that of punctures; summit of declivity at midlength; explanate margin narrow, with fringe of long setae. Metasternal glabrous area length less than width (as 14: 20), subrhomboidal, anteriorly nearly attaining intercoxal process, shining, convex. Abdominal ventrites 1 – 2 and basally 3 with hydrofuge pubescence. Aedeagus (Fig. 8): Length of main­piece 0.25 mm, length to tip of parameres 0.26 mm; lobes relatively long and slender, each with two barbs; dorsal notch U­shaped, widest apically, slightly deeper than ventral notch; apical paramere seta elongate, much longer than other setae. Females have the elytral explanate margin similar to that of males; the anterior margin of the labrum is arcuate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCBFFF9FEC77C7A6AE0F2FE.taxon	etymology	Etymology. Named in reference to the body form.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFCBFFF9FEC77C7A6AE0F2FE.taxon	distribution	Distribution. Currently known from northern Queensland and northern Northern Territory (Fig. 74).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF5FFC7FEC77CC26941F066.taxon	description	(Figures 15, 16, 80)	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF5FFC7FEC77CC26941F066.taxon	materials_examined	Type Material. Holotype (male): Australia: Victoria: 10 km NE Mirranatwa, small creek bed ­ drying pool, stony, dead leaves, dry sclerophyll forest, 37 ° 36 ' S, 142 ° 13 ' E, 12 October 1997, C. Watts. Deposited in the SAMA. Paratypes (41): Australia: New South Wales: Berry, 34 ° 46 ' S, 150 ° 42 ' E, 1 – 30 January 1968, C. Watts (4 SAMA); Tasmania: “ 3794 ” [no other data, no date], A. Simson (2 SAMA); St. Helens, 41 ° 20 ' S, 148 ° 15 ' E, 1 – 30 January 1962, C. Watts (1 SAMA); Victoria: 10 km NE Mirranatwa, small creek bed ­ drying pool, stony, dead leaves, dry sclerophyll forest, 37 ° 36 ' S, 142 ° 13 ' E, 12 October 1997, C. Watts (21 SAMA); Avon River, at Princes Hwy. bridge, Stratford, gravelly cobble­bank at edge of riffle of river, elev. 10 m, 37 ° 58 ' S, 147 ° 4 ' E, 19 September 1999, N. Porch (56) (1 ANIC); Holey Plains State Park, firedam on Crooke Track, fine sand and organics at the edge of a small firedam in dry sclerophyll forest, elev. 45 m, 38 ° 10 ' S, 146 ° 20 ' E, 16 April 2002, N. Porch (87) (12 ANIC). Representative specimens to be deposited in MCZ, MVMA, NMW, NPC, and QMBA.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF5FFC7FEC77CC26941F066.taxon	diagnosis	Differential Diagnosis. Recognized by the confluent anterior and posterior pronotal foveae, the shining dorsal reliefs, the moderately coarsely punctate pronotum, and the striate­impressed elytral series. This species shows some resemblance to G. semicylindrus, but is distinguished therefrom by the smaller size (ca. 1.75 vs. 1.86), the flatter body form, the confluent pronotal foveae, the arcuate lateral margins of the pronotum, and the slightly less coarsely punctate pronotum and elytra (Figs. 15, 17). The male genitalia of the two species also suggest a relationship, but in G. wattsi the duct is very large compared to the lobes, the lobes are rounded apically in ventral aspect, and the parameres do not extend beyond the tips of the lobes (Figs. 16, 18).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF5FFC7FEC77CC26941F066.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.75 / 0.75; head 0.33 / 0.44; pronotum 0.37 / 0.56; elytra 1.07 / 0.75. Form moderately ovate, moderately convex. Color dark brown to piceous, dorsal reliefs shining. Frons moderately finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal midlongitudinal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength: apical width as 7: 13, more densely punctate laterally than medially, pubescence denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum length: width as 5: 13; anterior margin arcuate, with low upturned apicomedian tooth. Maxillary palpomere 3 twice length of 4. Pronotum lateral hyaline border well developed, origin at base of lateral depression, sharply arcuate, almost angulate, to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly arcuate in midregion; each lateral depression with posterior in form of right angle, lateral margin arcuate from anterior angle then shallowly emarginate before posterior angle; lateral margin with very short fringe of setae; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, punctures on reliefs deep, moderately small and irregularly spaced; median groove deep, narrow, extending nearly to margins, constricted in midlength and tapering at ends, margins irregular, punctate; anterior foveae well developed, deep; posterior foveae oblique, linear impressions nearly 1 / 2 as long as and as wide as median groove; posterolateral angles with indistinct shallow impressions. Elytra moderately convex on disc, sides nearly vertical in basal 0.5, with six rows of punctures in well developed striae between suture and humeri; each puncture with a recumbent seta that overlaps base of following seta; intervals rounded, slightly wider than striae, smooth and shining; posterior declivity gradual, summit slightly past midlength; explanate margin narrow, without fringe of setae. Metasternal glabrous area length equal to or slightly greater than width (as 16: 15), subrhomboidal, shining, convex. Abdominal ventrites 1 – 3 and basally 4 with hydrofuge pubescence. Aedeagus (Fig. 16): Length of main­piece 0.28 mm, parameres not extended beyond tips of lobes; lobes in ventral aspect apically rounded, not barbed, tips bent in oblique aspect; ventral notch V­shaped, widest apically, dorsal notch U­shaped, not as deep as ventral notch; duct very wide, ca. 2 x width of lobes in lateral aspect, roundly, slightly expanded at tip; apical paramere seta elongate, ca. 2 x length of next longest seta. Females have the elytral explanate margin similar to that of males; the anterior margin of the labrum is weakly apicomedially emarginate.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF5FFC7FEC77CC26941F066.taxon	etymology	Etymology. Named in honor of the water beetle taxonomist, Chris Watts.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFF5FFC7FEC77CC26941F066.taxon	distribution	Distribution. Currently known from southern New South Wales, southern Victoria, and Tasmania (Fig. 80).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEDFFDFFEC77AD96861F02B.taxon	materials_examined	Type Material. Holotype (male): Australia: Northern Territory: Finke River xing, Stuart Highway, flowing river (temporary), sandy base, over­hanging vegetation, 24 ° 33 ' S, 133 ° 14 ' E, 4 March 1995, T. Weir. Deposited in the ANIC. Paratypes: Same data as holotype (2 ANIC).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEDFFDFFEC77AD96861F02B.taxon	diagnosis	Differential Diagnosis. Recognized by elongate body form and legs, the comparatively large elytra, the large and deep pronotal foveae, the shining dorsal reliefs, the light brown to testaceous color, and the raised even­numbered elytral intervals which are distinctly higher than the odd­numbered intervals. Distinguished from similarly shaped species G. benesculptus and G. coruscus by the elytral sculpture, the smaller size (ca. 1.70 mm vs. 2.00 mm), and the non­barbed aedeagus (Figs. 46, 47).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEDFFDFFEC77AD96861F02B.taxon	description	Description. Size (length / width, mm) holotype: body (length to elytral apices) 1.67 / 0.76; head 0.31 / 0.36; pronotum 0.39 / 0.53; elytra 1.03 / 0.76. Form moderately ovate, moderately convex. Head piceous, pronotum and elytra light brown to testaceous. Dorsal reliefs shining. Head finely sparsely punctate, weakly pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, pubescence very sparse on disc, denser and longer laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum length 0.5 width, anterior margin strongly arcuate; apicomedian tooth strong, behind which is weak oval depression. Pronotum lateral hyaline border well developed, origin at base of lateral depression, margin straight then markedly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum weakly arcuate in midregion; each lateral depression wide, posterior angle produced to acute point, lateral margin arcuate, with very short fringe of setae; lateral fossulae deep, very effacedly if at all microreticulate; pronotal disc transversely weakly convex, finely sparsely punctate, each puncture with a very small recumbent seta; median groove wide and deep, markedly constricted slightly behind midlength, extending nearly to margins, tapering at ends; anterior foveae oval, deep and large, width about equal widest part of median groove; posterior foveae oblique, deep, slightly more than 1 / 2 as long as and as wide as median groove; posterolateral angles without impressions. Elytra moderately convex on disc, with six rows of punctures in deep striae between suture and humeri; punctures round, usually separated from each other by less than puncture width, sometimes narrow walls; even­numbered intervals raised, distinctly higher than odd­numbered intervals, width slightly greater than that of punctures; summit of declivity near apical 0.66; striae 2 and 3 terminating into 4 at about apical 1 / 4; intervals 4 and 6 continuing in raised condition to apices; sutural margin slightly raised; elytral explanate margin moderately developed, without fringe of setae. Metasternal glabrous area longer than wide (as 14: 12), oval, shining, convex. Abdominal ventrites 1 – 3 and basal part of 4 with hydrofuge pubescence. Aedeagus (Fig. 47): Length of main­piece 0.32 mm, length to tip of parameres 0.38 mm; lobes relatively wide, not barbed; notches U­shaped, narrowed slightly subapically; duct markedly arcuate subapically; apical paramere seta elongate, much longer than other setae. Females have the explanate elytral margin about twice as wide as it is in males, about equal to the width of the mesotibia; the elytral sutural margins are sometimes weakly emarginate just before the apices, forming a narrow gap between the elytra; the labrum is simple, lacking the apicomedian tooth found in males.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEDFFDFFEC77AD96861F02B.taxon	etymology	Etymology. Named in honor of the collector, Tom Weir.	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
975A7812FFEDFFDFFEC77AD96861F02B.taxon	distribution	Distribution. Currently known only from the type locality in the Finke River Gorge National Park area of central Australia (Fig. 74).	en	Perkins, Philip D. (2005): A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea. Zootaxa 1024 (1): 1-161, DOI: 10.11646/zootaxa.1024.1.1, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1024.1.1
