Orphnebius bicuspis, 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 : 55-56

Orphnebius bicuspis spec. nov.

( Figs 9–10 , 34 , 44 , 253–260 )

Type material: Holotype ♂: “ Laos-N ( Louangphrabang ), 11–21.v.2002, 19°35'N, 101°58'E, Thong Khan , ~ 750 m, Vít Kubáň leg. / Holotypus ♂ Orphnebius bicuspis sp. n., det. V. Assing 2015” ( NHMB).

Paratypes: 12 exs. [3 teneral]: same data as holotype ( NHMB, cAss) ; 2 ♀♀: “ Laos, 1.–16.v.1999, Louangphrabang pr., 20°33–4'N 102°14'E, Ban Song Cha (5 km W), 1200 m, Vít Kubáň leg.” ( NHMB, cAss) ; 2 ♂♂: “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 ” ( ZFMK, cAss) .

Etymology: The specific epithet (Latin, adjective) alludes to the bifid ventral process of the aedeagus.

Description: Body length 2.7–4.1 mm; length of forebody 1.4–1.8 mm. Coloration: forebody black; abdomen red; legs with the femora blackish-brown, the tibae brown to dark-brown, and the tarsi reddish; antennae blackish with antennomeres II–III often, rarely also IV, slightly paler (brown to dark-brown); maxillary palpi pale-brown with the apical palpomere yellowish.

Head ( Figs 34 , 44 ) of transversely rectangular shape, approximately 1.4 times as broad as long; posterior angles nearly obsolete; posterior margin truncate or weakly convex; dorsal surface nearly impunctate. Eyes large, more than twice as long as postocular region in dorsal view. Antenna ( Figs 9–10 ) approximately 1.0 mm long; antennomere I very short, approximately as long as the combined length of antennomeres II and III; antennomere IV distinctly transverse and flattened; antennomere V much broader than antennomere IV; antennomeres V–X distinctly asymmetric, moderately flattened, and strongly transverse, more than twice as broad as long, and gradually increasing in width; XI approximately as long as the combined length of VIII–X.

Pronotum ( Figs 34 , 44 ) approximately 1.4 times as broad as long and as broad as head, moderately convex in crosssection; lateral and posterior margins together nearly forming a semi-circle, posterior angles completely obsolete; disc with a median pair of punctures, otherwise practically impunctate; lateral margins with one long and stout, and with two moderately long and rather fine erect black setae.

Elytra ( Figs 34 , 44 ) 0.70–0.77 times as long as pronotum; punctation sparse and fine; pubescence long, fine, pale, and sub-erect or depressed. Hind wings fully developed. Tibiae unmodified. Metatarsomere I slightly shorter than the combined length of II and III.

Abdomen: tergites III–VI with a lateral setiferous puncture on either side, VI with four additional punctures at posterior margin; tergite VII with dense non-setiferous punctures in posterior two-thirds, posterior margin with palisade fringe; tergite VIII ( Fig. 260 ) with a lateral cluster of fine setae on either side, posterior margin truncate in the middle and without teeth; sternite VIII with broadly convex posterior margin.

♂: segments IX–X distinctly modified (of the O. hauseri type), with dense and long pubescence; median lobe of aedeagus ( Figs 253–255 , 258–259 ) approximately 0.7 mm long; ventral process short and bifid; paramere ( Fig. 256 ) approximately 0.6 mm long, with slender condylite; paramerite of distinctive shape, external margin notched at apical two-fifths.

♀: segments IX–X distinctly modified ( O. hauseri type), with dense and long pubescence; proximal portion of spermathecal capsule simply curved, near distal portion distinctly modified ( Fig. 257 ).

Intraspecific variation: There are slight differences in the shape of the bifid apex of the ventral process of the aedeagus of the males from Arunachal Pradesh and from Laos. However, the external characters ( Figs 9–10 , 34 , 44 ) and the shape of the paramere are identical, so that the observed differences are attributed to intrarather than interspecific variation.

Comparative notes: Based on the shape of the head, the antennae, and the pronotum, the lateral clusters of setae on the abdominal tergite VIII, as well as on the bifid ventral process of the aedeagus and the morphology of the spermatheca, O. bicuspis belongs to the O. serratus subgroup. It is distinguished from O. serratus and other representatives of this subgroup by the non-dentate posterior margin of tergite VIII, as well as by the different shapes of the median lobe and the parameres of the aedeagus, from O. serratus additionally by smaller average body size, a narrower pronotum, and undilated protibiae. Regarding the bifid ventral process of the aedeagus, as well as the similar head shape, O. bicuspis is similar to O. incisus PACE, 2000 , which was originally described from Thailand and subsequently reported also from Yunnan ( PACE 2000, 2012b). Orphnebius bicuspis is distinguished from this species by slightly larger size ( O. incisus : 3.4 mm), the coloration of the antennae ( O. incisus : antennomeres I–V brown, VI–XI black), the more transverse head, by the larger median lobe of the aedeagus ( O. incisus : <0.5 mm, if the scale and the drawings are correct) and by the shorter and more broadly separated apices of the ventral process. For illustrations of O. incisus see PACE (2000).

Distribution and natural history: Orphnebius bicuspis is known from two localities in Louangphrabang province ( Laos) and one in Arunachal Pradesh; the type locality is identical to that of O. serratus . The specimens were collected at altitudes between 700 and 1200 m, in Laos together with O. dilatatus , O. extensus , O. serratus , O. latitibialis , O. lunatus , O. nigrapicalis , O. reductus , O. retunsu s, O. cultellatus , and O. carinatus , and in Arunachal Pradesh together with O. spinans and O. dispar . At least the material from India was collected with a flight interception trap. Three of the type specimens from Laos are teneral.

Figures

Figs 1–26. Antenna (1–21) and forebody (22–26) of Orphnebius spp. of the O. hauseri group: spinans (1, 23), cernens (2, 24), lunatus (3, 25), bakeri (4, 26), breviceps (5), extensus (6), serratus (7), integer (8), bicuspis, Laos (9), bicuspis, NE India (10), fusicollis (11), retunsus (12), fodens (13), opticus (14), dilatatus (15), fuscapicalis (16), grandicollis (17, 22), reductus (18), biformis, male (19), biformis, female (20), effeminatus (21). Scale bars: 22–26: 1.0 mm; 1–21: 0.5 mm.

Figs 27–39. Forebody (27–34), abdomen (35–37), mesotibia (38), and protibia (39) of Orphnebius spp. of the O. hauseri group: fuscapicalis (27, 35), dilatatus (28, 36), latitibialis (29, 38), breviceps (30), extensus (31), serratus (32, 39), integer (33, 37), bicuspis, Laos (34). Scale bars: 27–37: 1.0 mm; 38–49: 0.5 mm.

Figs 40–53. Forebody (40–50), abdomen (51), and antenna (52–53) of Orphnebius spp. of the O. hauseri group (40–49) and of the subgenus Deroleptus (50–53): opticus (40), effeminatus (41), biformis, male (42), biformis, female (43), bicuspis, NE India (44), retunsus (45), fusicollis (46–47), fodens (48), reductus (49), niger (50–52), siamensis (53). Scale bars: 1.0 mm.

Figs 236–257. Orphnebius serratus (236–243), O. integer (244–250), O. latitibialis (251–252), and O. bicuspis from Laos (253– 257): median lobe of aedeagus in lateral and in ventral view (236–237, 244–245, 253–254); apex of median lobe in ventral view (238, 246, 255); paramere (239, 247, 256); tergite VIII (240, 249, 252); spermatheca (241–243, 251, 257); apex of paramerite (248); postero-median portion of tergite VIII (250). Scale bars: 0.2 mm.

Figs 258–276. Orphnebius bicuspis (258–260; 258–259: India), O. opticus, syntype (261–262), O. fusicollis (263–268), O. reductus (269–273), and O. biformis (274–276): median lobe of aedeagus in lateral and in ventral view (258–259, 263–264, 269–270); tergite VIII (260, 261, 266, 272, 275); spermatheca (262, 268, 273, 276); paramere (265, 271, 274); anteromedian portion of sternite VIII (267). Scale bars: 0.2 mm.