Systenus apicidigitatus, Lin & Zhang & Yang, 2023

Lin, Chen, Zhang, Chunmin & Yang, Ding, 2023, The genus Systenus Meigen, 1803 (Diptera: Dolichopodidae) from Yunnan, China, with descriptions of six new species, Zootaxa 5383 (2), pp. 153-166 : 154-156

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.

Figures

FIGURES 1–6. 1. Systenus apicidigitatus sp. nov.; 2. Systenus basiflavus sp. nov.; 3. Systenus digitatus sp. nov.; 4. Systenus flavilateralis sp. nov.; 5. Systenus huanglianus sp. nov.; 6. Systenus latimaculatus sp. nov. All male. Scale bar =1.0mm.

FIGURES 7–8. Systenus apicidigitatus sp. nov. (male). 7. Antenna; 8. Male genitalia, lateral view. Scale bar = 0.1mm. Abbreviations: hyp = hypandrius, ph = phallus, epl = epandrial lobe, sur = surstylus, cer = cercus. FIGURES 9–10. Systenus basiflavus sp. nov. (male). 9. Antenna; 10. Male genitalia, lateral view. Scale bar = 0.1mm.