Stilicoderus daweianus, Assing, 2015

Assing, Volker, 2015, On Stilicoderus and Stiliderus IV. Two new species from China and additional records (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 47 (1), pp. 145-161 : 154-157

Stilicoderus daweianus nov.sp. ( Figs 15-28 )

T y p e m a t e r i a l: Holotype 3: " CHINA [22a] - Yunnan, SE Pingbian, primary forest, 22°54'31''N, 103°41'44''E, 2100 m, 28.VIII.2014, V. Assing / Holotypus 3 Stilicoderus daweianus sp. n. det. V. Assing 2015" (cAss). Paratypes: 233, 2♀♀ [one female slightly, one female distinctly teneral]: same data as holotype (cAss).

E t y m o l o g y: The specific epithet is an adjective derived from the name of the mountain where the type locality is situated.

D e s c r i p t i o n: Body length 7.8-8.7 mm; length of forebody 5.0- 5.1 mm. Habitus as in Fig. 15 . Coloration: body black; legs blackish with blackish-brown tarsi; antennae blackish-brown with blackish antennomere I.

Head ( Fig. 16 ) 1.03-1.07 times as broad as long; lateral margins behind eyes smoothly curving towards posterior constriction of head in dorsal view, posterior angles obsolete; punctation very dense and moderately coarse, not umbilicate ( Fig. 17 ), interstices very narrow; dorsal surface with very weak shine. Eyes moderately large and moderately convex, less than half as long as distance from posterior margin of eye to posterior constriction in dorsal view. Antenna ( Fig. 18 ) 2.5-2.6 mm long.

Pronotum ( Fig. 16 ) approximately 1.05 times as long as broad and 0.95 times as broad as head; punctation very dense and distinctly granulose; interstices barely noticeable; surface practically matt; midline with narrow impunctate band.

Elytra ( Figs 16, 19 ) approximately 0.9 times as long as pronotum; humeral angles marked; punctation moderately dense, irregularly spaced, coarse, and non-granulose, laterally arranged in indistinct series; interstices without microreticulation, but with scattered micropunctation. Hind wings present. Tarsi simple. Metatarsomere I approximately as long as the combined length of II and III.

Abdomen much narrower than elytra ( Fig. 15 ); anterior impressions of tergites III-V with moderately coarse and irregularly spaced macropunctation and with pronounced microreticulation; remainder of tergal surfaces with very dense and fine punctation and with fine, but distinct microreticulation; posterior margin of tergite VII with palisade fringe; posterior margin of tergite VIII weakly convex ( Fig. 24 ).

3: sternite VII ( Fig. 25 ) strongly transverse, posterior margin in the middle with concavity, this concavity furnished with very dense dark setae ( Fig. 26 ); sternite VIII ( Fig. 27 ) transverse, posterior excision broadly triangular, pubescence along midline denser than in lateral portions and directed posteriad, in lateral portions diagonally latero-posteriad, near posterior excision with very dense pubescence ( Fig. 28 ); aedeagus ( Figs 20-23 ) 1.3-1.4 mm long (measured from apices of apical structure to base of aedeagal capsule); ventral process very short and laterally compressed; apical internal structure strongly sclerotized, apically bispinose (ventral view), and basally with wingshaped lateral projections.

C o m p a r a t i v e n o t e s: Stilicoderus daiwanus is readily distinguished from all its congeners by the highly distinctive morphology of the aedeagus and the conspicuous shapes and chaetotaxy of the male sternites VII and VIII. In fact, these structures are so different from those of all other Stilicoderus species that closer affiliations to other species or to any of the existing species groups are not evident. Based on the external characters (habitus; punctation of the forebody), S. daweianus is tentatively assigned to the S. signatus group. In this context, it seems noteworthy that a new Lathrobium species found at the same locality, L. coadultum ASSING , in press, similarly represents a monotypical and most distinctive species group (ASSING in press).

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 Dawei Shan near Pingbian in southeastern Yunnan, China, not far from the border with Vietnam. The partly teneral type specimens were sifted from moist leaf litter and soil between stones under a bush in a subtropical primary forest at an altitude of 2100 m. Numerous other undescribed species were found in the same locality.

Figures

Figs 15-22: Stilicoderus daweianus nov.sp.: (15) habitus; (16) head and pronotum; (17) anteromedian portion of head; (18) antenna; (19) elytra; (20-21) aedeagus in lateral and in ventral view; (22) aedeagus in dry preparation in lateral view. Scale bars: 15-16, 18-19: 1.0 mm; 17, 20-22: 0.5 mm.

Figs 23-28: Stilicoderus daweianus nov.sp.: (23) aedeagus in dry preparation in ventral view; (24) male tergite VIII; (25) male sternite VII; (26) postero-median portion of male sternite VII; (27) male sternite VIII; (28) median portion of male sternite VIII. Scale bars: 23-25, 27: 0.5 mm; 26, 28: 0.2 mm.