Orphnebius (Deroleptus) sexcarinatus, 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 : 67

Orphnebius (Deroleptus) sexcarinatus spec. nov.

( Figs 57, 81–84 , 314–316 )

Type material: Holotype ♀: “ Sumatra: Aceh #25b, Mt Leuser NP , 300–500 m, Ketambe , 23–30.XI.1989, Löbl, Agosti, Burckhard / Holotypus ♀ Orphnebius sexcarinatus sp. n., det. V. Assing 2015” ( MHNG).

Etymology: The specific epithet (adjective) alludes to the six oblong setiferous tubercles at the posterior margin of the abdominal tergite VI.

Description: Body length 7.2 mm; length of forebody 3.3 mm. Coloration: head blackish-brown; pronotum dark-brown; elytra dark-yellowish with the posterolateral portions infuscate; abdomen reddish with segment VI slightly and segment VII distinctly darker; legs pale-reddish; antennae blackish-brown with antennomeres I–IV and the apex of antennomere XI reddish; maxillary palpi reddish with the apical palpomere yellowish.

Head ( Fig. 84 ) transverse, 1.25 times as broad as long (length measured from sclerotized portion of clypeus), lateral and posterior margins behind eyes broadly rounded; dorsal surface with a distinct lateral puncture on either side and with few scattered smaller punctures at or near dorsal margin of eyes, otherwise impunctate; interstices without microsculpture; sclerotized portion of clypeus very short. Eyes large, approximately as long as the distance from posterior margin of eye to posterior constriction in dorsal view. Antenna ( Fig. 57 ) 2.15 mm long and slender; antennomere IV strongly oblong, approximately twice as long as broad; V nearly twice as long as broad; VI approximately 1.5 times as long as broad; VII weakly oblong; VIII approximately as long as broad; IX and X weakly transverse; XI slightly longer than the combined length of IX and X.

Pronotum ( Fig. 84 ) weakly transverse, 1.07 times as broad as long and approximately as broad as head, strongly convex in cross-section; lateral margins subparallel and straight in dorsal view; anterior margin strongly concave in the middle; disc with a median pair of punctures, otherwise practically impunctate.

Elytra ( Fig. 84 ) approximately 0.8 times as long as, and much broader than pronotum; punctation fine and sparse, less sparse anteriorly than posteriorly, postero-sutural angles practically impunctate. Hind wings fully developed. Legs long and slender; mesofemur conspicuously modified: postero-ventral surface distinctly flattened, even slightly concave in cross-section; metatibia weakly curved in apical half; metatibia 1.55 mm, mesotarsus 1.3 mm long; metatarsomere I very long, nearly as long as the combined length of II–IV.

Abdomen ( Figs 81–83 ) broader than elytra; lateral margin of sternite III broadly, triangularly developed, with a short and acute spine-shaped apex; sternite IV with a pronounced long and spine-shaped postero-lateral process; paratergites III and IV very broad; tergites III– VI each with two lateral setiferous punctures on either side; tergite V additionally with a median pair of punctures slightly behind middle and with a pair of median punctures at posterior margin; tergite VI additionally with a median pair of setiferous tubercles slightly behind middle and with six oblong setiferous tubercles at posterior margin, the lateral tubercle anteriorly extending into a long carina; tergite VII with dense non-setiferous punctation anteriorly and with dense longitudinal striae in posterior third, near posterior margin with a transverse row of approximately six long black setae, posterior margin with palisade fringe; tergite VIII ( Fig. 314 ) oblong, flattened, with three pronounced tooth-like projections at posterior margin, and in anterior portion with two extensive clusters of numerous gland openings; sternite VIII ( Fig. 315 ) with a transverse band of gland openings at anterior third, posterior margin broadly produced and weakly convex.

♂: unknown.

♀: spermatheca ( Fig. 316 ) with short distal and proximal portions.

Comparative notes: This species differs from O. gracilior , with which it shares a similar habitus, by much larger body size, much less slender antennomeres IV–X, the coloration of the legs, less slender head and pronotum, modified mesofemora, the modifications of the abdominal sternites III–IV, the modifications of tergite VI, a much broader abdomen, the presence of a median pair of punctures on tergites V and VII, an oblong tergite VIII with much more pronounced posterior teeth, and by the shape of the spermatheca. Orphnebius sexcarinatus is readily distinguished from the three Orphnebius species previously recorded from Sumatra by much larger size and completely different coloration alone.

Distribution and natural history: The type locality is situated in Aceh, North Sumatra, Indonesia, at an altitude between 300 and 500 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 84–101. Forebody (84–90), abdomen (91–94, 97–98), lateral portion of abdominal segments III–V/VI (95, 99, 101), and tergite VII (96, 100) of Orphnebius spp. of the subgenus Deroleptus: sexcarinatus (84), spoliatus (85, 91), cultellatus (86, 92–94), septemcuspis (87, 95–96), tortus (88, 98–100), vates (89, 97), baccillatus (90, 101). Scale bars: 84–95, 97–99, 101: 1.0 mm; 96, 100: 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.