Stilicoderus chengrani sp. n.

(Figs 2, 8–12)

Type material. Holotype: male, " China, Xizang, Muotuo, alt. 1500–2000 m, 20.VIII.2013, Wen-Xuan Bi leg." (SNUC). Paratypes: 1 male, 1 female, " China, Xizang, Hanmi, 12–31.VII.2013, alt. 2100 m, Wen-Xuan Bi leg." (SNUC); 6 males, 7 females, "Hanmi, Motuo Coun., Xizang A. R. alt. 2200 m, 19.VIII.2005, TANG Liang leg." (SNUC); 1 male, "Hanmi, Motuo Coun., Xizang A. R. alt. 2200 m, 23-27.VIII.2005, TANG Liang leg." (SNUC); 1 male, "Dongjiu, Linzhi Coun., Xizang A. R., alt. 2800 m, 3.VIII.2005, TANG Liang leg." (SNUC).

Description. Body length: 5.4–5.9 mm; length of forebody: 3.5–3.8 mm.

Coloration: body blackish, elytra with obliquely oval dark-yellowish spot in anterior half; legs yellowish, femoral apices very narrowly blackish; antennae reddish with infuscate antennomere I.

Head (Fig. 8) 0.94–0.95 times as broad as long, widest across eyes, smoothly tapering behind eyes, somewhat produced posteriorly; lateral margins smoothly curving towards posterior constriction, posterior angles completely obsolete; punctation dense, relatively fine, and defined, somewhat sparser in median dorsal portion; interstices without microsculpture. Eyes moderately large and distinctly projecting from lateral contours of head, approximately one third as long as distance from posterior margin of eye to posterior constriction.

Pronotum (Fig. 8) 1.18–1.30 times as long as broad and 0.57–0.78 as wide as head; surface covered with tiny, setose tubercles; midline with broad impunctate band.

Elytra (Fig. 8) 0.68–0.75 times as long and 1.27–1.33 times as broad as pronotum; non-setiferous puncture-like impressions coarser, interspersed with fine and very dense setiferous punctures. Hind wings fully developed.

Abdomen narrower than elytra; punctation very fine and dense; interstices with distinct microsculpture, particularly on posterior tergites; posterior margin of tergite VII with palisade fringe.

♂: posterior margin of sternite VII (Fig. 9) weakly concave at middle; sternite VIII (Fig. 10) with posterior excision almost V–shaped and rather deep; aedeagus (Fig 11, 12) 0.61–0.65 mm long, with apical internal structures straight and long; ventral process long and sinuate, curved ventrally in apical portion in lateral view, strongly curved to the left in ventral view.

Comparative notes. Based on external and the male sexual characters, S. chengrani belongs to the S. signatus group. The similar male sexual characters suggest that S. chengrani is closely related to S. clayi Rougemont, 1986, from which it is distinguished by the narrower excision of male sternite VIII, and the ventrally curved apical portion of ventral process of the aedeagus.

Distribution and biological notes. The specimens were collected from two localities in Xizang Province, China, by sifting leaf litter at altitudes from 1500 to 2800 m.

Etymology. This species is named in honor of Ran Cheng, brother of the first author.