Orsunius affimbriatus, Assing, 2015

Assing, Volker, 2015, On Orsunius III. Four new species from China and Thailand, and additional records (Coleoptera: Staphylinidae: Paederinae: Medonina), Linzer biologische Beiträge 47 (1), pp. 83-96 : 85-86

Orsunius affimbriatus nov.sp. ( Figs 1-5 )

T y p e m a t e r i a l: Holotype 3: " CHINA: Guangdong prov. [MF 16], W of Qixing, 1- 3.v.2011, Heishiding nature reserve, 23°27.9'N, 111°54.3'E, 190-260 m, Fikáček & Hájek / sifting of moist leaf litter in the dried-up streambeds and along the streams in the primary lowland forest / Holotypus 3 Orsunius affimbriatus sp.n. det. V. Assing 2015" (NMP). Paratypes: 2♀♀: same data as holotype (NMP, cAss).

E t y m o l o g y: The specific epithet (Latin, adjective) alludes to the absence of a palisade fringe at the posterior margin of the abdominal tergite VII.

D e s c r i p t i o n: Body length 3.7-4.3 mm; length of forebody 1.9-2.0 mm. Coloration: body, including antennae and mouthparts, more or less uniformly reddish; legs slightly paler, yellowish-red.

Head ( Fig. 1 ) weakly transverse, approximately 1.13 times as broad as long; lateral margins behind eyes subparallel in dorsal view; frons (between eyes) transversely impressed; posterior angles moderately marked; posterior margin distinctly concave in the middle; punctation non-umbilicate, dense and moderately coarse, sparse in median dorsal portion; interstices without microsculpture. Eyes relatively small, approximately 0.6 times as long as postocular portion in dorsal view. Antennae approximately 1.1 mm long; preapical antennomeres weakly transverse. Anterior margin of labrum with Ushaped excision in the middle. Right mandible with three molar teeth.

Pronotum ( Fig. 1 ) weakly transverse, approximately 1.05 times as wide as long and about as broad as head; posterior angles rounded, weakly marked; punctation moderately coarse and dense, similar to that of head; midline with rather narrow impunctate band; interstices without microsculpture.

Elytra ( Fig. 1 ) short, approximately 0.75 times as long as pronotum, noticeably dilated laterad; punctation fine and dense; interstices without microsculpture. Hind wings completely reduced. Protarsomeres I-IV not distinctly dilated. Metatarsomere I longer than II, but shorter than the combined length of II and III.

Abdomen slightly broader than elytra; punctation fine and dense on tergites III-IV, gradually sparser from tergite V to tergite VIII; interstices without microreticulation and glossy; posterior margin of tergite VII without palisade fringe.

3: sternite VII ( Fig. 2 ) nearly 1.2 times as broad as long and with distinctly concave posterior margin; sternite VIII ( Fig. 3 ) distinctly oblong and with shallow posterior excision; aedeagus ( Figs 4-5 ) 0.48 mm long, ventral process distinctly separated from median lobe in apical portion and somewhat asymmetric in ventral view.

C o m p a r a t i v e n o t e s: Based on external and particularly the male sexual characters, O. affimbriatus is closely related to O. wunderlei and allied species. It is easily distinguished from all other species of the genus by the shorter elytra, the completely reduced hind wings, the absence of a palisade fringe at the posterior margin of tergite VII, the distinctly concave posterior margin of the male sternite VII, the shape of the male sternite VIII, and by the shape of the aedeagus. For illustrations of other Orsunius species see ASSING (2011, 2014).

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: The type locality is situated in the northwest of Guangdong province, not far from the border with Guangxi, South China. As can be inferred from the adaptive reductions of the elytra, the hind wings, and the palisade fringe at the posterior margin of tergite VII, O. affimbriatus probably has a restricted distribution. The type specimens were sifted from moist leaf litter in and along dry streams beds in a lowland forest at an altitude of 190- 260 m.

Figures

Figs 1-5: Orsunius affimbriatus nov.sp.: (1) forebody; (2) male sternite VII; (3) male sternite VIII; (4-5) aedeagus in lateral and in ventral view. Scale bars: 1: 0.5 mm; 2-5: 0.2 mm.