Orphnebius tridentatus, Assing, 2015

Assing, Volker, 2015, On the Orphnebius fauna of the East Palaearctic region. VI. Six new species from China and Taiwan, and additional records (Coleoptera: Staphylinidae: Aleocharinae: Lomechusini), Linzer biologische Beiträge 47 (1), pp. 101-125 : 106-108

Orphnebius tridentatus nov.sp.

( Figs 1-8 )

Type material: Holotype ♂: " CHINA: Yunnan, Lincang Pref., Wuliang Shan , old pass road, W side, 24°42'58.6''N, 100°29'52.0''E, 2200 m, small creek valley with primary forest remnant, litter sifted, 16.IX.2009, leg. M. Schülke [CH09-47a] / Holotypus ♂ Orphnebius tridentatus sp. n., det. V. Assing 2015" ( cAss).

Etymology: The specific epithet (Latin, adjective: with three teeth) alludes to the shape of the abdominal tergite VIII.

Description: Body length 4.7 mm; length of forebody 1.8 mm. Coloration: head and pronotum blackish; elytra blackish-brown; abdomen bicoloured, with segments III-V, VIII-X, and anterior fifth of segment VI yellowish-red, and with segment VII and posterior four-fifths of segment VI blackish-brown; legs dark-brown with paler tarsi; antennae with antennomere I-III reddish-brown, IV brown, and V-XI blackish.

Head ( Fig. 1 ) approximately as long as broad; punctation fine and sparse. Eyes large and bulging, but noticeably shorter than distance from posterior margin of eye to posterior constriction in dorsal view. Antenna ( Fig. 2 ) long and slender, 1.5 mm long, symmetric, somewhat resembling those of species of Calliceru s GRAVENHORST, 1802 and Ilyobates KRAATZ, 1856 ; antennomeres III conspicuously oblong, approximately three times as long as broad, IV-X cylindric, IV approximately 1.5 times as long as broad, V oblong, VI weakly oblong, VII approximately as long as broad, VIII-IX weakly transverse, X moderately transverse, and XI shorter than the combined length of IX and X.

Pronotum ( Fig. 1 ) weakly transverse, 1.1 times as broad as long and 1.22 times as broad as head, broadest at posterior angles; lateral margins weakly diverging posteriad and nearly straight; posterior angles obtusely marked; posterior margin strongly convex; disc with very few scattered setiferous punctures, laterally with sparse setiferous punctures and with two long black setae on either side; lateral margins without long black setae; microsculpture absent.

Elytra ( Fig. 1 ) slightly shorter, and at posterior margin much broader than pronotum; punctation fine and sparse; pubescence long, dark, and suberect. Hind wings present.

Abdomen ( Fig. 3 ) wedge-shaped, widest at base; tergites III-VI with sharp and pronounced paratergites gradually decreasing in height; tergites III-V impunctate except for some minute punctures at posterior margins, a long and stout black seta in posterolateral angles on either side, and with few setae on paratergites; tergite VI impunctate and without pubescence on disc, but with two long and black lateral setae on either side, with four long black setae at posterior margin, and with one long seta on paratergite on either side, near lateral margin with a longitudinal fold in posterior third; tergite VII with conspicuously coarse and dense non-setiferous punctures; posterior margin of tergite VII with pronounced palisade fringe.

♂: tergite VIII ( Fig. 4 ) posteriorly with a small median and two larger lateral projections of triangular shape; sternite VIII ( Fig. 5 ) of distinctive shape; median lobe of aedeagus ( Figs 6-7 ) small and slender, 0.35 mm long, and without sclerotized internal structures; parameres ( Fig. 8 ) slender, 0.35 mm long, and weakly modified.

♀: unknown.

Comparative notes: Based on the external characters (head approximately as long as broad; antennal morphology; modifications of abdominal tergites VI and VII; posterior margin of tergite VIII tricuspidate), O. tridentatus undoubtedly belongs to the O. nanlingensis group, which previously included O. tricuspis (male sexual characters unknown) and O. nanlingensis (Fujian, Guangdong). It differs from the former by less massive antennae with more slender antennomeres IIII and IV, by the paler coloration ( O. tricuspis : femora black; apex of abdomen darker), by the less slender and less convex (cross-section) pronotum ( O. tricuspis : pronotum 1.05 times as broad as long), the different sculpture of the abdominal segments VI and VII ( O. tricuspis : tergite VI with more pronounced and longer lateral fold and with additional median folds posteriorly), and by the smaller median projection of the abdominal tergite VIII. The new species is separated from O. nanlingensis by different coloration ( O. nanlingensis : abdomen not distinctly bicoloured, more or less uniformly dark-brown; antennae reddish-brown), the shape of the head ( O. nanlingensis : noticeably transverse), longer and more slender antennae, the shorter and less pronounced postero-lateral folds on the abdominal tergite VI, the differently shaped posterior margin of tergite VIII, as well as by the morphology of the aedeagus ( O. nanlingensis : median lobe 0.4 mm long; ventral process straight in lateral view and with longer and more acute apex in ventral view). For illustrations of O. tricuspis and O. nanlingensis see ASSING (2006b, 2009).

Distribution and natural history: The type locality is situated in the Wuliang Shan in West Yunnan. The holotype was sifted from leaf litter in a primary forest remnant at an altitude of 2200 m.

Figures

Figs 1-8: Orphnebius tridentatus nov.sp.: forebody (1); antenna (2); abdomen (3); male tergite VIII (4); male sternite VIII (5); median lobe of aedeagus in lateral view (6); median lobe of aedeagus in ventral view (7); paramere (8). Scale bars: 1-3: 1.0 mm; 4-5: 0.2 mm; 6-8: 0.1 mm.