Systenus digitatus, 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 : 158-160

3. Systenus digitatus sp. nov.

( Figs 3 , 11–12 )

Diagnosis. Postpedicel rather long, 3.0 times longer than wide, basally rather thick, apically finger-like; arista 0.65 times as long as postpedicel. All coxae yellow. Epandrial lobe short wide with six finger-like processes. Surstylus rather wide with narrow and slightly curved tip.

Description. Male ( Fig. 3 ). Body length 2.5 mm, wing length 2.0 mm.

Head metallic green with pale gray pollinosity. Frons metallic green with white gray pollinosity; face dark metallic green with dense silvery white pollinosity, narrower than width of postpedicel. Hairs and bristles on head black, but lower postocular bristles yellowish. 2 oc, 2 vt, 2 pvt. Antenna blackish; pedicel with blackish apical bristles; postpedicel rather long, 3.0 times longer than wide, basally rather thick, apically long finger-like, and with dense dark brown pubescence; arista apical, brown, 0.65 times as long as postpedicel, with very short dark brown pubescence ( Fig. 11 ). Proboscis short, brownish with brownish yellow hairs; palpus small, dark brown, with black hairs and 1 black apical bristle.

Thorax metallic green with pale gray pollinosity, but pleura blackish to black. Hairs and bristles on thorax black; 5 dc; 5 to 6 irregular pairs of acr; 2 strong npl, 1 strong sa, 1 strong pa; sc long and strong, lsc short and hair-like.

Legs mainly yellow to dark yellow; all coxae yellow; all tarsi brownish yellow with tarsomere 5 brownish. Hairs and bristles on legs black except those on coxae dark yellow and hind coxa with 1 brown strong outer bristle at middle. Hind trochanter with 1 blackish bristle. Mid tibia with 1 ad, 1 pd, 1 av, and 3 apical bristles; hind tibia with 2 ad and 2 apical bristles. Mid tarsomere 1 with 5 pv, tarsomere 2 with 3 pd and 2 apical bristles. Relative length of tibiae and five tarsomeres of legs LI 2.1: 1.0: 0.9: 0.6: 0.5: 0.5; LII 3.0: 1.5: 1.1: 0.8: 0.5: 0.4; LIII 3.5: 0.8: 1.5: 0.8: 0.6: 0.4.

Wing hyaline, weakly tinged brownish; veins dark brown; M 1 bent medially; R 4+5 and M 1 widened at first, then convergent apically; CuAx ratio 0.6. Squama yellow with blackish hairs. Halter pale yellow.

Abdomen dark metallic green with pale gray pollinosity, venter brownish yellow. Hairs and bristles on abdomen black. First tergum with very long black bristles at posterior margin.

Male genitalia ( Fig. 12 ): epandrium distinctly longer than wide; epandrial lobe basally short wide with six finger-like processes, apically long spine-like; surstylus rather wide with narrow and slightly curved tip. Cercus basally rather wide, apically finger-like. Hypandrium long finger-like. Phallus long and thin.

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) .

Distribution. China (Yunnan).

Remarks. Systenus digitatus sp. nov. is somewhat similar to S. basiflavus sp. nov. in having the postpedicel distinctly elongated and surstylus elongated with a small dorsal process near base, but can be easily separated from the latter by the following features: antenna wholly blackish; surstylus nearly straight with a very short dorsal process directed forward; cercus not furcated apically.

Etymology. The specific name refers to the epandrial lobe with six finger-like processes.

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 11–12. Systenus digitatussp. nov. (male). 11.Antenna; 12. Male genitalia, lateral view.Scale bar = 0.1mm. FIGURES 13–14. Systenus flavilateralis sp. nov. (male). 13. Antenna; 14. Male genitalia, lateral view. Scale bar = 0.1mm.