Orphnebius (Deroleptus) gracilior, Assing, 2016

Assing, Volker, 2016, On some Lomechusini of the Palaearctic and Oriental regions (Coleoptera: Staphylinidae: Aleocharinae), Beiträge Zur Entomologie = Contributions to Entomology 66 (1), pp. 13-111 : 66-67

Orphnebius (Deroleptus) gracilior spec. nov.

( Figs 56, 72, 77–80 , 311–313 )

Type material: Holotype ♀: “ NE India , Arunachal Pr ., Etalin vicinity , 700 m, 28°36'56"N, 95°53'21"E, FIT (flight interception trap), L. Dembický leg., 12.–25.v.2012 / Holotypus ♀ Orphnebius gracilior sp. n., det. V. Assing 2015” ( ZFMK).

Paratype ♀: same data as holotype (cAss) .

Etymology: The specific epithet is the comparative of the Latin adjective gracilis (slender) and alludes to the conspicuously slender body, legs, and antennae.

Description: Body length 5.0– 5.7 mm; length of forebody 2.1–2.2 mm. Coloration: head and pronotum dark-brown; elytra pale-brown with the postero-lateral portions extensively dark-brown; abdomen with tergites III–V and VIII–X dark-reddish to brown and tergites VI–VII dark-brown to blackish-brown with reddish posterior margins; legs yellowish with the apical portions of the femora weakly infuscate; antennae with antennomeres IV–XI brown and I–III partly reddish; maxillary palpi brown to dark-brown with the apical palpomere yellowish.

Head ( Fig. 72 ) weakly transverse, 1.02–1.05 times as broad as long, tapering behind eyes, posterior angles obsolete; lateral dorsal portions with moderately sparse and extremely fine punctation; median dorsal portion extensively without punctation; interstices without microsculpture. Eyes large, as long as, or slightly longer than the distance from posterior margin of eye to posterior constriction in dorsal view. Antenna ( Fig. 56 ) 2.1 mm long and conspicuously slender; antennomere IV strongly oblong, more than three times as long as broad; V approximately three times as long as broad; VI approximately 2.5 times as long as broad; VII twice as long as broad; VIII–X of decreasing length and decreasingly oblong; X weakly oblong; XI slightly longer than the combined length of IX and X.

Pronotum ( Fig. 72 ) slender, 1.05 times as long as broad and as broad as, or slightly broader than head, strongly convex in cross-section; lateral margins in posterior half slightly sinuate in dorsal view; anterior margin strongly concave in the middle; disc with a median pair of punctures, otherwise practically impunctate.

Elytra approximately 0.85 times as long as, and much broader than pronotum; punctation distinct and moderately dense, denser anteriorly than posteriorly. Hind wings fully developed. Legs conspicuously long and slender; mesotibia weakly, metatibia distinctly curved in apical half; metatibia 1.3 mm, mesotarsus 1.1 mm long; metatarsomere I nearly as long as the combined length of II–IV ( Fig. 80 ).

Abdomen ( Figs 77–79 ) long and slender, narrower than elytra, gradually tapering posteriad; paratergites III each with acute, horizontal, and moderately long posterolateral process; posterior margin of tergite III with a more or less pronounced median spine; tergites III–VI each with two lateral setiferous punctures on either side; tergite VI with a long lateral keel on either side; tergite VII anteriorly with six pronounced oblong impressions separated by narrow carinae, in median third with conspicuously coarse non-setiferous punctation, in posterior third with longitudinal striae, in the middle of posterior portion with a pronounced median keel, on either side of this keel with a setiferous tubercle, posterior margin with a palisade fringe; tergite VIII ( Fig. 311 ) transverse, weakly tridentate posteriorly, anteriorly with numerous gland openings, in median portion with very short and fine setae, and in posterior portion with approximately ten setiferous tubercles.

♂: unknown.

♀: sternite VIII ( Fig. 312 ) transverse, laterally with a few stout setae inserting in blunt processes, posterior margin convex; spermatheca ( Fig. 313 ) small in relation to body size, approximately 0.23 mm long and with proximal portion of distinctive shape.

Comparative notes: Based on the similar external characters (habitus, punctation, tricuspidate posterior margin of tergite VIII; chaetotaxy of sternite VIII), this species belongs to the O. niger group. Among the species of this group it somewhat resembles O. tricuspis in size and body shape, but differs from this species by much longer and more slender legs and antennae, distinctly paler coloration (particularly of the legs), larger eyes, a more slender pronotum with sinuate lateral margins, and different modifications of the abdominal segments III, VI, VII, and VIII, and by the completely different shape of the spermatheca.

Distribution and natural history: The type locality is situated in Arunachal Pradesh, northeastern India, and identical to that O. spinans and O. dispar . The specimens were collected with a flight interception trap at an altitude of 700 m.

Figures

Figs 54–83. Antenna (54–69), forebody (70–73), abdomen (74–76), abdominal segments III–V (77, 81), lateral portion of abdominal segments III–V (78, 82), tergites VI–VII (79, 83), and hind leg (80) of Orphnebius spp. of the subgenus Deroleptus: discrepans (54, 73, 75), triapicalis (55, 71, 76), gracilior (56, 72, 77–80), sexcarinatus (57, 81–83), spoliatus (58), cultellatus (59), septemcuspis (60), vates (61), tortus (62), baccillatus (63), carinatus (64), dispar (65), laticeps (66), biimpressus (67), ulcerosus (68), falagrioides (69), siamensis (70, 74). Scale bars: 70–83: 1.0 mm; 54–69: 0.5 mm.

Figs 296–316. Orphnebius niger (296–298), O. siamensis (299–303), O. discrepans (304–306), O. triapicalis (307–310), O. gracilior (311–313), and O.sexcarinatus (314–316): tergite VIII (296, 302, 310, 311, 314); female sternite VIII (297, 312, 315); spermatheca (298, 313, 316); median lobe of aedeagus in lateral and in ventral view (299–300, 304–305, 307–308); paramere (301, 306, 309); male sternite VIII (303). Scale bars: 0.2 mm.