Orphnebius (Deroleptus) triacuminatus, Assing, 2017

Assing, Volker, 2017, On the Lomechusini fauna of the East Palaearctic and Oriental regions, with a focus on the genera Orphnebius and Amaurodera (Coleoptera: Staphylinidae: Aleocharinae), Beiträge Zur Entomologie = Contributions to Entomology 67 (1), pp. 63-106 : 74-75

Orphnebius (Deroleptus) triacuminatus spec. nov.

urn:lsid:zoobank.org:act:A8C586C1-2037-4DE5-997C-7B5DFD7F8581

( Figs 1, 20–22 , 62–65 )

Type material: Holotype ♀: “NW Thailand, 23.– 31.5.1991, Mae Hong Son, Ban Si Lang , 1200 m, J. Horák leg. / Holotypus ♀ Orphnebius triacuminatus sp. n., det. V. Assing 2016” ( NMP).

Etymology: The specific epithet (adjective: with three tips) alludes to the shape of sternite VIII.

Description: Rather large species, body length 6.8 mm; length of forebody 2.6 mm. Coloration ( Figs 1, 20–21 ): head blackish; pronotum brown; elytra reddish with the postero-lateral portions extensively infuscate; abdomen brown with the anterior portions of the tergites more or less distinctly darker; legs dark-brown; antennae darkbrown with antennomeres I–II and the base of III pale brown and the apex of antennomere XI reddish.

Head ( Fig. 20 ) distinctly transverse, posteriorly vertically sloping ventrad towards neck; posterior angles completely obsolete; neck approximately 0.35 times as wide as head; punctation moderately coarse and rather dense in lateral portions of dorsal surface, absent along middle; microsculpture in median dorsal portion obsolete, very shallow in lateral portions. Eyes large, strongly bulging, and of oblong ellipsoid shape, not situated laterally, but dorsolaterally, posteriorly nearly reaching posterior margin of head. Antenna ( Fig. 1 ) approximately 2.2 mm long and slender; antennomeres IV oblong, V weakly oblong, VI–VII approximately as broad as long, VIII–X weakly transverse, and XI approximately as long as the combined length of IX and X.

Pronotum ( Fig. 20 ) moderately convex in cross-section, of transversely quadrangular shape, approximately 1.3 times as wide as long and as wide as head; anterior and posterior angles marked; disc with distinct impressions and elevation in median portion; punctation sparse and extremely fine, barely noticeable; pubescence short.

Elytra ( Fig. 20 ) distinctly widened posteriorly and approximately as long as pronotum; suture gaping posteriorly; punctation moderately sparse and distinctly granulose; interstices with pronounced microreticulation. Hind wings present. Legs conspicuously long and slender; mesotiba weakly, metatibia more strongly curved; metatibia 1.4 mm long.

Abdomen ( Fig. 21 ) wedge-shaped, distinctly tapering posteriad (lateral sternal processes not considered); sternite V postero-laterally with a conspicuous bifid process, those of sternites III and IV less pronounced ( Fig. 22 ); sternites VI–VIII without such processes; tergites III–V impunctate; tergite VI with four setiferous punctures at posterior margin; integument without microsculpture; posterior 3/5 of tergite VII and tergite VIII with coarse and dense non-setiferous punctation; posterior margin of tergite VII with distinct palisade fringe; sternite VIII ( Fig. 64 ) posteriorly with pair of lateral processes and pronounced median process.

♀: tergite VIII ( Figs 62–63 ) posteriorly with several denticles; spermatheca small in relation to body size, shaped as in Fig. 65 .

Comparative notes: As can be inferred particularly from the shape of sternite VIII, O. triacuminatus belongs to the O. draco group of the subgenus Deroleptus , which previously included two species from South China, O. draco ASSING, 2010 and O. multimpressus ASSING, 2015 ( ASSING 2016b). The new species is distinguished from them by smaller body size, paler coloration (particularly of the pronotum, the elytra, the abdomen, and the antennae), a different pattern of the impressions and elevations on the pronotum, and by less slender and shorter antennae. From O. multimpressus , with which it shares the similar shapes of the posterolateral processes of sternites III–V, it additionally differs by the shape and much smaller size of the spermatheca and by less numerous denticles at the posterior margin of tergite VIII. For illustrations of O. draco and O. multimpressus see ASSING (2010, 2015a).

Distribution: The type locality is situated in Northwest Thailand at an altitude of 1200 m.

Figures

Figs 1–30: Antenna (1–19), forebody (20, 23, 26), abdomen (21, 24, 27, 29), antero-lateral portion of abdomen in lateral-dorsal view (22, 25, 28), and abdominal segment VII (30) of Orphnebius triacuminatus (1, 20–22), O. gracilis (2, 23–25), O. protuberatus (3, 26–28), O. pertortus (4, 29–30), O. reticulipennis (5), Zyrastilbus almorensis (6), Pheidologitonetes bursata (7), Rabdotodrusilla vara (8), Amaurodera bicarinata (9), A. gilvicornis (10), A. latisulcata (11), A. brevipes (12), A. migritheca (13), A. longisetosa (14), A. calicitheca (15), Drusilla smetanai (16), D. nepalensis (17), D. lativentris (18), and Witteia tensa (19). Scale bars: 1–29: 1.0 mm; 30: 0.5 mm.

Figs 62–81: Orphnebius triacuminatus (62–65), O. niger (66–70), O. gracilis (71–74), O. protuberatus (75–78), and O. pertortus (79–81): female tergite VIII (62, 71, 75, 79); posterior margin of female tergite VIII (63); female sternite VIII (64, 72, 76, 80); spermatheca (65, 74, 78, 81); male tergite VIII (66); male sternite VIII (67); median lobe of aedeagus in lateral and in ventral view (68–69); paramere (70); medio-lateral portion of female sternite VIII (73, 77). Scale bars: 62, 64, 66–67:0.5 mm; 68–72, 75–76, 79–80: 0.2 mm; 63, 65, 73–74, 77–78, 81: 0.1 mm.