1. Systenus apicidigitatus sp. nov.

(Figs 1, 7–8)

Diagnosis. Antennal scape and pedicel dark brownish yellow. Postpedicel 4.0 times longer than wide. All coxae yellow, but mid coxa basally brown. R 4+5 and M 1 strongly convergent apically. Surstylus basally rather thick, apically long thin and finger-like. Male cercus strongly bent, basally very thick, apically with short thin ventral process.

Description. Male (Fig. 1). Body length 2.67–3.33 mm, wing length 2.33–3.0 mm.

Head metallic green with pale gray pollinosity. Frons metallic green with white gray pollinosity; face dark metallic green with thick silvery white pollinosity, narrower than postpedicel. Hairs and bristles on head black except lower postocular bristles yellowish. 2 oc, 2 vt, 2 pvt. Antenna black, but scape and pedicel dark brownish yellow; postpedicel 4.0 times longer than wide, nearly rectangular at basal 1/3, very long and thin at remaining 2/3, and with dark brown pubescence; arista 0.38 times as long as postpedicel, apical, with very short dark brown pubescence (Fig. 7). Proboscis short, brown to dark brown with brown hairs; palpus small, dark brownish yellow with short black hairs and 1 black long strong apical bristle.

Thorax metallic green with pale gray pollinosity. Hairs and bristles on thorax black; 6 dc; 9–10 irregular pairs of short acr; 2 strong npl, 1 strong sa, 2 strong pa; sc long and strong, lsc short and hair-like. Propleuron with 1 brown bristle on lower portion.

Legs mainly yellow; all coxae yellow, but mid coxa basally brown; all tarsomere 5 dark brown. Hairs and bristles on legs black, but those on coxae yellow. Fore leg without distinct bristles. Hind coxa with 1 brown outer bristle at base. Mid tibia with 1 ad, 2 pd and 3 apical bristles. Hind tibia with 4 short pd and 2 apical bristles. Mid tarsomeres 1–4 each with 1 ad at middle and 4 apical bristles. Relative length of tibiae and five tarsomeres of legs LI 3.0: 1.6: 1.0: 0.7: 0.5: 0.4; LII 4.3: 2.0: 1.5: 1.0: 0.7: 0.6; LIII 4.9: 0.9: 2.1: 0.7: 0.5: 0.8.

Wing hyaline, somewhat brownish; veins dark brown, R 4+5 and M 1 strongly convergent apically; CuAx ratio 0.6. Squama yellow with long black hairs; halter pale yellow.

Abdomen dark metallic green with pale gray pollinosity, venter yellowish. Hairs and bristles on abdomen black. Terga 1–4 with long bristles at apical margin.

Male genitalia (Fig. 8): epandrium distinctly longer than wide; epandrial lobe rather narrow, apically hook-like; surstylus basally rather thick, apically long finger-like. Cercus strongly bent, basally very thick, apically narrowed with short thin ventral process. Hypandrium very long, apically long finger-like. Phallus long, somewhat thickened, distinctly curved inward.

Female. Unknown.

Type material. HOLOTYPE ♂, China: Yunnan, Lvchun, Yakou, Shuikuxiafang [23°3’25.2”N, 102°46’37.71”E, 1779 m], collected by Malaise trap, 2019.IV.19–V.19, Liang Wang and Xin Li (CAU) . PARATYPES: 5 ♂, same data as holotype (CAU); 3 ♂, same data as holotype except, 2019.III.19–IV.19 (CAU) .

Distribution. China (Yunnan).

Remarks. Systenus apicidigitatus sp. nov. is very similar to S. huanglianus sp. nov., but may be separated from the latter by the following features: antennal two basal segments dark brownish yellow; R 4+5 and M 1 strongly convergent apically; postpedicel 3.5 times longer than wide.

Etymology. The specific name refers to the surstylus apically finger-like.