Orphnebius (Deroleptus) planicollis, 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 : 118-121

Orphnebius (Deroleptus) planicollis nov.sp.

( Figs 34-45 )

Type material: Holotype ♂: " CHINA [18] - Yunnan, mts S Jianshui, broad-leaved for., 23°25'20''N, 102°51'05''E, 1890 m, 22.VIII.2014, V. Assing / Holotypus ♂ Orphnebius planicollis sp. n., det. V. Assing 2015" ( cAss) . Paratype ♀: same data as holotype ( cAss).

Etymology: The specific epithet (Latin: adjective) alludes to the absence of impressions on the pronotum.

Description: Species of moderate and rather variable size ( Figs 34-35, 37-38 ), body length 5.2-6.0 mm; length of forebody 2.2-2.7 mm. Coloration: body brown to dark-brown, with the posterior and lateral margins of the abdominal segments paler; legs reddish with brown femora; antenna pale-reddish.

Head ( Figs 34-35 ) strongly transverse, approximately 1.45 times as wide as long, posteriorly vertically sloping ventrad towards neck, but not angled (lateral view); behind eyes abruptly curved; general outline of posterior margin transversely truncate, in the middle weakly, but distinctly concave; neck approximately 0.28 times as wide as head; punctation fine and rather sparse, absent along middle of dorsal surface; interstices without microsculpture. Eyes large, strongly bulging, and of oblong ellipsoid shape, not situated laterally, but dorso-laterally, nearly reaching posterior margin of head. Antenna ( Fig. 36 ) symmetric, 1.7-2.1 mm long, and slender.

Pronotum ( Figs 34-35 ) weakly convex in cross-section, of transversely trapezoid shape, 1.42-1.50 times as wide as long and 0.94-0.98 times as wide as head, broadest at or near anterior angles; anterior and posterior angles marked; posterior margin weakly concave in the middle; disc without impressions; punctation sparse and extremely fine, barely noticeable; pubescence fine, short, depressed, and whitish; laterally, anteriorly, and posteriorly distinctly margined and without long setae.

Elytra ( Figs 34-35 ) distinctly widened posteriorly and 1.31-1.38 times as long as pronotum; suture gaping posteriorly; along suture smoothly and weakly elevated; punctation moderately sparse, fine (but more distinct than that of pronotum), and not granulose; interstices without microreticulation; pubescence whitish, depressed, longer than that of pronotum. Hind wings present. Legs conspicuously long and slender; metatibia smoothly curved; metatibia 1.05-1.33 mm long; metatarsus 0.93-0.94 times as long as metatibia; metatarsomere I as long as, or slightly longer than, the combined length of II and III.

Abdomen ( Fig 37-39 ) wedge-shaped, distinctly tapering posteriad (lateral sternal processes not considered); sternites III and IV postero-laterally with conspicuous processes of distinctive, possibly sexually dimorphic shapes; tergites strongly transverse; tergites III-VI impunctate, except for a setiferous puncture in postero-lateral angles bearing a stout black seta; integument without microsculpture; tergite VII ( Fig. 40 ) with dense and coarse punctation nearly extending to anterior margin, near posterior margin with a transverse row of four to six coarse granules, posterior margin with palisade fringe; tergite VIII ( Fig. 40 ) with dense and coarse punctation (similar to those of tergite VII), posterior margin distinctly serrate and in the middle weakly to distinctly conave; sternite VIII posteriorly simply convex, without conspicuous processes.

♂: postero-lateral processes of sternites III and IV strongly developed, shaped as in Figs 37, 39 ; median lobe of aedeagus ( Figs 41-42 ) 0.65 mm long and of distinctive shape; lateral margins of ventral process furnished with numerous minute setae (best visible in ventral view); paramere ( Figs 43-44 ) 0.58 mm long; paramerite apically truncate, membranous, and with approximately three minute setae.

♀: postero-lateral processes of sternites III and IV less pronounced and of more simple shape than in male ( Fig. 38 ); spermatheca ( Fig. 45 ) 0.4 mm long and of highly distinctive shape.

Comment: At present, it is uncertain whether the differences in the shapes of the postero-lateral processes of the anterior abdominal sternites are related to body size or a sexual dimorphism. The female paratype is distinctly smaller than the male holotype.

Comparative notes: Orphnebius planicollis is easily distinguished from the other two Deroleptus species recorded from China ( O. draco , O. multimpressus ) by numerous characters, in particular its smaller size, the paler coloration of the body, the legs, and especially the antennae, the shape of the head (more transverse, posteriorly truncate and in the middle concave), the absence of impressions on the pronotum, the non-granulose punctation of the elytra, the absence of microsculpture on the elytra, the shapes of the postero-lateral processes of the anterior abdominal sternites, the coarsely, densely, and more extensively granulose sculpture of tergites VII and VIII, the simple sternite VIII (without pronounced posterior processes), and the distinctive shapes of the median lobe of the aedeagus, the paramere, and the spermatheca.

Distribution and natural history: The type locality is situated in a mountain range to the south of Jianshui, southeastern Yunnan, not far from the border with Vietnam. The specimens were sifted from litter in a subtropical broad-leaed forest at an altitude of 1890 m.

Figures

Figs 34-39: Orphnebius planicollis nov.sp. (34, 36-37, 39: holotype; 35, 38: paratype): male forebody (34); female foreboy (35); antenna (36); male abdomen (37); female abdomen (38); anterior portion of left side of abdomen in dorso-lateral view (39). Scale bars: 1.0 mm.

Figs 40-45: Orphnebius planicollis nov.sp.: (40); male abdominal segments VII-VIII in dorsal view (40); median lobe of aedeagus in lateral and in ventral view (41-42); paramere (43); apical portion of paramere (44); spermatheca (45). Scale bars: 40: 0.5 mm; 41-45: 0.2 mm.