Rhyparus loughlini Skelley and Smith, 2024

Rhyparus loughlini Skelley and Smith , new species

Figures 13–17 View Figures 13–17 , 29 View Figures 26–29 , 41 View Figure 41

Diagnosis. A member of Rhyparus , distinguished from all other Western Hemisphere species by the following combination of characters: dorsal body weakly alutaceous, appearing glossy with weak opalescence ; elytron with outside margin of submarginal costa in lateral view turning upward at a 90° angle at caudal bulb ( Fig. 15 View Figures 13–17 , 29 View Figures 26–29 ); flattened discomedian costa with caudal apex bearing large, prominent trichome; posteriorly flattened discolateral costa making posterior half of elytral disc appear flat (compare Fig. 17 View Figures 13–17 with Fig. 5 View Figures 1–5 , 22 View Figures 18–25 ); third elytral costal interval with three rows of round, distinctly separated punctures in basal half, two rows in apical half; last abdominal ventrite with a central foveate depression; and distribution in Mexico (Hidalgo, San Luis Potosí) ( Fig. 41 View Figure 41 ) .

Description. Holotype female ( Fig. 13–15 View Figures 13–17 ). Body length 4.00 mm, width 1.50 mm. Elongate, flattened, dark brownish black, weakly alutaceous, weakly dull with weak opalescence; partly clothed with indistinct, fine, very short setae on head and all longitudinal costae on pronotum and elytra.

Head. Surface weakly dull, weakly alutaceous, transversely subhexagonal ( Fig. 16 View Figures 13–17 ). Clypeus trapezoidal, anteriorly truncate in anterior view, concave between teeth in dorsal view; anterior margin narrowly upturned with obtuse tooth on each side of medial third, lateral thirds concave to rounded obtuse tooth anterior of clypeo-genal junction. Gena moderately lobed laterally, distinctly excavated anterior of eyes. Clypeocentral disc convex with two indistinct, longitudinal costae weakly evident in dorsal profile; peridiscal impression strong basally; anteriorly narrowly, weakly grooved, appearing as row of punctures. Frons with four small, low frontodiscal costae, lateral costae longer than medial costae. Head with evenly scattered fine punctures; coarser punctures at base of head, smaller punctures on clypeal disc; punctures with short, pale yellow setae.

Pronotum. Surface and costae weakly dull, widest in middle; with paramedian, discolateral, and submarginal costae distinct, all with anterior portions roundly costate. Paramedian costae incomplete, prominent at anterior margin, obsolete at constriction near anterior third, distinct and weakly diverging to posterior margin. Discolateral costa nearly straight, distinctly interrupted by fovea on anterior third, present at anterior margin. Submarginal costa complete, sinuate; posterior lobe small, broadly rounded laterally. Median interval at constriction of paramedian costa lacking coarse punctures. Other costal intervals impunctate except for four large pores at anterior margin and at basal third on each side of paramedian costa. Interval between discolateral and submarginal costae flattened posterior of fovea. Lateral margin deeply notched, with prominent anterior and intermediate lobes; anterior lobe slightly smaller and more triangular than intermediate lobe, posterior lobe lacking. Posterior marginal groove broad, deep, and crenated by pronotal costae.

Scutellum. Scutellar shield minute, narrow, apex acute.

Elytra. Surface weakly alutaceous, costae somewhat glossy, intervals opaquely dull, weakly opalescent; widest in middle; flattened intervals with coarse punctures distinctly separated. Costae convex, each slightly different. Juxtasutural costa complete from base to apex, weakly flattened. Discomedian costa mostly straight from base to apex; medially depressed, distinctly flattened, lower medially than at ends and discolateral costa; gradually swelling at apex to moderately large postdiscal bulb; trichome of costa large, encroaching onto dorsal surface of costa. Discolateral costa prominent, gradually enlarging posteriorly for entire length; distinctly sinuate, medially concave; in caudal view costa low, with apex of discolateral costa projecting laterally which gives caudal half of elytral disc a flattened appearance ( Fig. 17 View Figures 13–17 ). Posthumeral costa distinct, complete to apex, narrower than discolateral costa. Submarginal costa narrow entire length; turning upward at 90° angle and abruptly inward to caudal bulb ( Fig. 15 View Figures 13–17 ), forming a lateral angulation or lobe. Costal interval 1 (between juxtasutural and discomedian costae) flattened, with 13 coarse, distinctly separated punctures in outer row. Costal interval 2 (between discomedian and discolateral costae) with two rows of coarse, rounded, distinctly separated punctures. Costal interval 3 (between discolateral and posthumeral costae) with three rows of coarse, rounded, distinctly separated punctures; median puncture row present on basal half, punctures smaller than outer rows. Costal interval 4 (between posthumeral and submarginal costae) with punctures somewhat transverse, connected or nearly so to adjacent row in basal half; rugose-washboard surface distinct medially, lesser so toward base. Caudal trichomes at end of discomedial costa large; trichome small at ends of discolateral and posthumeral costae, hidden; trichome of caudal bulb narrowed, transversely elongate. Caudal bulbs moderately large, transverse; in dorsal view, weakly prominent laterally, curving inward and caudally near juxtasutural costa; anterior margin projecting forward, dividing trichome opposite of discomedian costa; in caudal view, somewhat triangularly rounded dorsally, with posterior angulation of submarginal costa appearing somewhat bilobed laterally. Dorsal surface of caudal bulb alutaceous, weakly glossy, apparently impunctate, with scattered minute setae; surface between bulb and caudal margin of elytra concave with several foveate punctures.

Ventral thorax. Surface alutaceous, dull, punctures bearing a short seta. Metaventrite flattened; median longitudinal groove on posterior two-thirds of ventrite, as wide as mesotarsi, weakly narrowing anteriorly; disc on either side of groove with minutely punctured area bounded laterally by longitudinal row of impressed coarse punctures, appearing like a groove; punctures on remainder off disc fine medially, becoming larger anterolaterally.

Abdomen. Abdominal ventrites 2–4 with narrow, transverse, anterior groove fluted, posterior margin with row of shallow small punctures; ventrites laterally with indistinct, shallow, triangular depression with coarse punctures, depression more distinct on posterior ventrites; rest of surface with scattered, fine punctures bearing a short seta. Abdominal ventrite 5 (last) as long as preceding three ventrites medially; surface evenly coarsely punctate, punctures separated by one puncture diameter or more; medially with small medial fovea; laterally with transversely elongate triangular fovea; anterior margin with wide, punctate groove extending to lateral margin. Apical half of pygidium apical half with central carina basally split, Y-shaped; top of Y prominent, tuberculate; depressed surface in lateral view angularly concave at base ( Fig. 29 View Figures 26–29 ); each side of median carinae with alutaceous, triangular depression.

Legs. All femora dull, with moderately deep, distinct punctures; all punctures bearing a very short seta. Profemoral punctures enlarged and prominent, mesofemoral and metafemoral punctures moderate in size and less distinct. Mesofemur robust medially; posterior margin weakly sinuate, weakly convex with swelling at middle and apical third. Metafemur narrow, moderately widened medially. Protibia with two distinct lateral teeth at apex; inner apical third tooth minute; medial margin straight in apical third. Mesotibia with apex truncate; female lacking large, medially projecting spine on inner apical angle; inner margin straight in apical quarter. Metatibia weakly widened to truncate apex; female lacking large, medially projecting tooth on inner apical angle; inner margin straight in apical third. Mesotarsomere 1 as long as mesotarsomeres 2–4; ventral setae fine, glossy surface visible. Metatarsomere 1 as long as metatarsomeres 2–5 combined.

Male. Unknown.

Variation. Paratype female body length 3.81 mm, width 1.31 mm. The row of punctures on each side of the median longitudinal groove of metaventrite not impressed, not notably groove-like. This character is known to vary in other species. Other characters do not differ notably.

Material examined. Holotype female deposited in CMNC: “MEX: SLP; 1600m / 20 Km W. Xilitla / 12.VI–6.VIII-83 / S&J.Peck, FIT / cloud forest // [bordered label] H & A Howden / COLLECTION / Ottawa , Canada // [large bordered label] [hand written] Rhyparus / n.sp. / [printed] DET / H.F. HOWDEN 96 [with year handwritten] // [red paper] HOLOTYPE ♀ / Rhyparus / loughlini / des. 2024 / Skelley & Smith”.

Paratypes. Only one additional female specimen was examined: “ MEXICO: Hidalgo / 2.5–3.5 mi. N. Tlan- / chinol, 50–5200 ft / vii.11.1973 // Newton / Collector // Berl. leaf litt. / cloud forest” ( FSCA).

Etymology. Named for Thomas Loughlin, a student from the University of Waterloo, who did an internship at the Canadian Museum of Nature.

Comments. Other undescribed Rhyparus in the group to which R. loughlini belongs, also have a central coarsely punctured foveate depression in the middle of the last abdominal ventrite. This depression varies in development between species, from being prominent to lacking. In addition, it is sexually dimorphic in some, were males have the punctures and the depression finely divided, appearing as two small depressions. This dimorphism is expected in R. loughlini .

The small size, somewhat glossy, opalescent surface, sharply angled submarginal costa, and other diagnostic characters make R. loughlini unique among Western Hemisphere Rhyparus . This species is one of several new species that do not appear to be attracted to lights, thus rarely collected. More focused collecting in leaf litter is needed to learn about this under-sampled fauna.