Neosclerus vietnamensis, Assing, 2017

Assing, Volker, 2017, A revision of Neosclerus CAMERON VI. Three new species from India, Thailand, and Vietnam (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 49 (1), pp. 317-325 : 322-324

Neosclerus vietnamensis nov.sp. ( Figs 18-23 )

T y p e m a t e r i a l: Holotype Ƌ: "N-Vietnam - 6 km NW Sa Pa, 22°21'39''N, 103°47'19''E, 1810 m, pasture margin, 7.VIII.2013, V. Assing [8+2] / Holotypus Ƌ Neosclerus vietnamensis sp.n. det. V. Assing 2015 " (cAss). Paratypes: 2♀♀: same data as holotype, but leg. Wunderle (cWun, cAss).

E t y m o l o g y: The specific epithet is an adjective derived from Vietnam.

D e s c r i p t i o n: Body length 3.0- 3.5 mm; length of forebody 1.7-1.9 mm. Coloration: body black; legs and antennae dark-brown.

Head ( Fig. 18 ) moderately transverse, approximately 1.2 times as broad as long; punctation of dorsal surface coarse, non-umbilicate, moderately dense in anterior and median portions, and rather sparse posteriorly; interstices without microreticulation. Eyes very large and bulging, separated from posterior margin of head by less than the width of antennomere II.

Pronotum ( Fig. 18 ) approximately as broad as long and 0.9 times as broad as head; punctation similar to that of median portion of head; interstices without microsculpture and glossy; midline narrowly impunctate and with fine furrow of variable length posteriorly.

Elytra ( Fig. 18 ) 0.91-0.94 times as long as pronotum; punctation dense, fine, and weakly defined. Hind wings present, but possibly of reduced length. Metatarsomere I nearly as long as the combined length of metatarsomeres II and III.

Abdomen approximately as broad as elytra; punctation fine and dense; interstices with shallow microreticulation; posterior margin of tergite VII with palisade fringe.

Ƌ: sternite VII ( Fig. 19 ) weakly tranverse, 1.1 times as broad as long, posterior margin broadly and very indistinctly concave (nearly truncate) in the middle, in postero-median portion with slightly stouter black setae; sternite VIII ( Figs 20-21 ) very weakly oblong, extensively without pubescence in median and postero-median portions, without setae at margins of posterior excision, and with few setae in antero-median portion, posterior excision V-shaped, its depth approximately one-seventh the length of sternite; aedeagus ( Figs 22-23 ) 0.55 mm long; ventral process straight, apically acute, and subapically with a pair of small teeth.

C o m p a r a t i v e n o t e s: Based on the male primary and secondary sexual characters, N. vietnamensis belongs to the N. brevipennis group. The male sexual characters are highly similar to those of N. biangulatus ASSING, 2015 ( Thailand) , from which N. vietnamensis differs by distinctly shorter elytra ( N. biangulatus : elytra approximately 1.1 times as long as pronotum) with distinctly denser punctation, paler coloration of the legs ( N. biangulatus : legs dark-yellowish), the shape of the posterior margin of the male sternite VII, and a slightly more slender ventral process of the aedeagus. Even though the differences in the male sexual characters are not pronounced, N. vietnamensis is hypothesized to represent a distinct species, not only because the differences in external characters (especially the shape and punctation of the elytra) are conspicuous and apparently constant, but also because interspecific variation in the male sexual characters is generally low in the N. brevipennis group.

For illustrations of the external and male sexual characters of other species of the N. brevipennis group see ASSING (2011, 2013, 2015).

D i s t r i b u t i o n a n d b i o n o m i c s: Neosclerus vietnamensis represents the second record of the genus from Vietnam. The type locality is situated near a pass to the northwest of Sapa, North Vietnam. The specimens were sifted from leaf litter and the roots of herbs beneath bushes and small trees at the margin of a pasture at an altitude of 1810 m ( Fig. 24 ).

Figures

Figs 18-23: Neosclerus vietnamensis nov.sp.: (18) forebody; (19) male sternite VII; (20-21) male sternite VIII in lateral and in ventral view; (22-23) aedeagus in lateral and in ventral view. Scale bars: 18: 0.5 mm; 19-23: 0.2 mm.

Fig. 24: Type locality of Neosclerus vietnamensis nov.sp.