Stilicoderus hainanus, 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 : 150-151

Stilicoderus hainanus nov.sp. ( Figs 1-8 )

T y p e m a t e r i a l: Holotype 3: " CHINA: Hainan isl. [MF23], Bawangling Nat. Forest Park, 12.3 km SEE of Baotie, 19°5.20'N 109°11.80'E, 1050 m, 8.v.2011; Fikáček / siftings: moist accumulations of leaf litter along a stream in a primary forest / Holotypus 3 Stilicoderus hainanus sp. n. det. V. Assing 2014 " ( NMP).

E t y m o l o g y: The specific epithet is an adjective derived from Hainan, the name of the island where the species was discovered.

D e s c r i p t i o n: Body length 4.8 mm; length of forebody 2.8 mm. Coloration: body black; legs dark-reddish; antennae with antennomeres I-IV blackish-brown, antennomeres V-XI gradually paler, apical antennomeres reddish-brown.

Head ( Fig. 1 ) approximately as broad as long; lateral margins immediately behind eyes subparallel, broadly curving towards posterior constriction of head in dorsal view, posterior angles practically obsolete; punctation very dense, rather fine, and not umbilicate, interstices very narrow ( Fig. 6 ); dorsal surface with very weak shine. Eyes moderately large and strongly bulging, approximately 0.35-0.40 times as long as distance from posterior margin of eye to posterior constriction in dorsal view. Antenna 1.6 mm long

Pronotum ( Fig. 1 ) approximately as broad as long and as broad as head; punctation very dense and distinctly granulose ( Fig. 7 ); interstices barely noticeable; surface practically matt; midline without impunctate band.

Elytra ( Fig. 1 ) 0.93 times as long as pronotum; humeral angles marked; punctation dense and granulose, somewhat less dense than that of pronotum, with numerous additional coarser, irregularly spaced, and non-setiferous puncture-like impressions ( Fig. 8 ); interstices without microreticulation; surface less matt than that of pronotum. Hind wings fully developed.

Abdomen noticeably narrower than elytra; posterior margin of tergite VII with palisade fringe.

3: sternite VII ( Fig. 2 ) strongly transverse, approximately twice as broad as long, posterior margin broadly concave, in the middle indistinctly bisinuate, with fringe of numerous long and thin marginal setae; sternite VIII ( Fig. 3 ) strongly transverse, 1.5 times as broad as long, with broadly and moderately deeply concave posterior margin, and with a postero-lateral cluster of long thin setae on either side, median portion with longitudinal sculpture ( Fig. 4 ); aedeagus ( Fig. 5 ) 0.65 mm long, with pair of ventroapical structures and with sclerotized internal structures of various shapes (partly extruded in holotype).

C o m p a r a t i v e n o t e s: Based on the external and male sexual characters, S. hainanus belongs to the S. variolosus group. It is distinguished from other species of this group by the morphology of the aedeagus and by the shapes and chaetotaxy of the male sternites VII and VIII, from the geographically close and externally similar S. trapezeiceps (ROUGEMONT, 1986) additionally by different head shape ( S. trapezeiceps : head distinctly dilated posteriad) and by the coloration of the legs ( S. trapezeiceps : legs dark-brown to blackish-brown. According to ROUGEMONT (pers. comm.), S. hainanus is more similar to S. parvus (CAMERON, 1936) (Java, Sumatra) in external characters and in the shape of the ventral process of the aedeagus than to S. trapezeiceps . It differs from S. parvus particularly by the much more deeply concave posterior margin of the male sternite VIII and by the strongly bent apico-ventral sclerotized structures of the aedeagus. For illustrations of S. parvus and S. trapezeiceps see ROUGEMONT (1986a).

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: Stilicoderus hainanus is the first representative of the genus to be recorded from the Chinese island Hainan. The type locality is situated in the west of the island, near Baotie. The holotype was sifted from moist leaf litter along a stream in a primary forest at an altitude of 1050 m.

Figures

Figs 1-5: Stilicoderus hainanus nov.sp.: (1) forebody; (2) male sternite VII; (3) male sternite VIII; (4) median portion of male sternite VIII; (5) aedeagus in lateral view (internal sac partly extruded). Scale bars: 1: 1.0 mm; 2-5: 0.2 mm.

Figs 6-14: Stilicoderus hainanus nov.sp. (6-8) and S. wrasei ASSING (9-14; 9, 12: holotype; 10, 13: Xundian env.; 11, 14: Wuding env.): (6) median portion of head; (7) median portion of pronotum; (8) left elytron; (9-11) aedeagus in lateral view; (12-14) male sternite VIII. Scale bars: 9-15: 0.5 mm; 6-8: 0.2 mm.