Ochosternus huttoni Rosas, Chan & Reid, 2025

Ochosternus huttoni Rosas, Chan & Reid , new species

( Figs 22–31 View FIGURE 22 View FIGURES 23–24 View FIGURES 25–26 View FIGURES 27–29 View FIGURES 30–32 )

Description (female only)

Length: 21 mm; greatest width of pronotum at hind angles 1.7× width of head; greatest width of elytra slightly broader than pronotum; blackish brown with reddish-brown appendages, antennomeres with dark brown median streak.

Head. Dorsum medially slightly depressed, with semi-erect setae, anteriorly directed; unevenly punctured, anterior punctures smaller and partly congruent, discal punctures larger but sparser, insterspaces 0.5–1.5× diameters; interspaces shiny, not microsculptured; anterior margin of head in dorsal view convex, slightly projecting laterally beyond eyes, smooth and impuncate but not carinate, abruptly raised above base of labrum; interocular space about 4.5× eye widths in dorsal view; labrum strongly and densely punctured, with long setae, anterior edge feebly concave; outer surface of mandibles strongly punctured and setose on proximal half, smooth and impunctate on distal half, with elongate depression at midpoint; antennae about 0.3× body length; scape and antennomeres 3–11 elongate, pedicel quadrate; antennomeres 3–11 expanded, elongate triangular, with apicolateral angle slightly projecting; relative lengths of antennomeres: female: 11> 3> 1> 4=7=8=9> 5=6=10> 2.

Thorax. Pronotal length and breadth about equal, sides expanded from anterior to middle, then slightly sinuate to posterior angles, width at posterior angles 1.5× width at anterior angles; disc convex, with deep circular depression either side and shallow midline groove; pronotal punctures similar to disc of head but less dense, interspaces 1.5–3× diameters; interspaces shiny, faintly microreticulate; setae of disc semierect, variably directed but mostly worn off so difficult to determine directions, generally similar to O. howensis ; anterior angles of lateral pronotal carina visible from above; posterior angles of pronotum about 40°; prosternal and hypomeral punctures larger and denser than pronotal disc, with anteriorly directed depressed setae; mesoscutellar disc slightly concave, sparsely finely punctured and setose; elytral striae with distinct elongate punctures, intervals closely stongly punctured, punctures similar to strial or pronotal punctures but shallow; apices of elytra rounded, with minute sutural angulation; metaventrite densely and strongly punctured and setose, punctures slightly smaller than on hypomeron, setae recumbent and posteriorly directed.

Abdomen. Ventrites with punctures and setae similar to metaventrite but punctures smaller; posterior margin of sternite 7 shallowly concave.

Female genitalia. Tergite 8 almost triangular but with rounded sides and deeply concave basal margin; sternite 8 almost circular, with close erect setae throughout, basal strut about 2.2× length of sclerite; coxites elongate-rectangular, not subdivided, overlapping along basal 2/3 of midline, with projecting narrow elongate-rectangular tips, which slightly diverge, and subapical cylindrical styli; paraprocts long, about 6× length of coxites, slightly expanded anteriorly towards rounded apices; internal surface of bursa copulatrix with two dense patches of short spines at anterior end, without distinct sclerotised plates, lateral lobe present, twisted with small patch of internal spines, globular spermatheca attached to apex of lobe.

Diagnosis. The following attributes distinguish O. huttoni from the other two species of Ochosternus on Lord Howe Island: anterior margin of head not carinate ( Fig. 25 View FIGURES 25–26 ); antennomeres 3–10 serrate in female ( Fig. 26 View FIGURES 25–26 ); pronotal disc with shallow circular depression each side of midline ( Figs 27–28 View FIGURES 27–29 ); lateral margins of pronotum entirely visible in dorsal view, slightly sinuate in posterior half ( Figs 27–28 View FIGURES 27–29 ); scutellar disc shallowly concave, sparsely punctured ( Fig. 27 View FIGURES 27–29 ); female sternite 8 without apical tuft of setae ( Fig. 30 View FIGURES 30–32 ); gonocoxites broad, parallel-sided for most of length then abruptly contracted to apical quarter ( Fig. 31 View FIGURES 30–32 ).

Material examined. Types. Holotype: f/ NSW, Mt Gower, Lord Howe Island, bottom of southernmost gully, -31.35.18, 159.4.21, 18-Jan-2002 to 31-Jan-2002, I. Hutton, ca. 670m; MG 16/01 (pit trap)/ Ochosternus huttoni Rosas, Chan & Reid 2025 Holotype / AM K187173/ ( AMS) [specimen missing both mesothoracic legs & tip of right antenna; apex of ovipositor damaged after habitus photography].

Etymology. Named for Ian Hutton, director of the Lord Howe Island Museum, who collected the unique specimen on behalf of the Australian Museum.

Notes. Ochosternus huttoni is only known from a deep gully in the stunted cloud forest on the summit of Mount Gower, which is protected as part of Lord Howe Island National Park. It does not overlap in distribution with O. howensis , which is confined to taller forest at lower elevation, 5–500 m asl ( Fig. 22 View FIGURE 22 ). Immature stages are unknown.