Systenus basiflavus Lin & Zhang & Yang 2023, sp. nov.
Creators: name: Lin, Chen
name: Zhang, Chunmin
name: Yang, Ding
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Systenus
Systenus basiflavus

description: 2. Systenus basiflavus sp. nov.
(Figs 2, 9–10)
Diagnosis. Antenna brownish except scape and pedicel dark yellow; postpedicel 3.3 times longer than wide, with slightly thick portion at base. Fore and hind coxae yellow, but mid coxa dark brown. Surstylus geniculate with a finger-like dorsal process near base. Male cercus apically bifurcated with dorsal lobe slightly shorter than ventral lobe.
Description. Male (Fig. 2). Body length 2.58–2.7 mm, wing length 2.33–2.5 mm.
Head metallic green with pale gray pollinosity. Frons metallic green with white gray pollinosity; face dark metallic green with dense silvery white pollinosity, nearly as wide as the width of postpedicel. Hairs and bristles on head black, but postocular bristles yellowish. 2 oc, 2 vt, 2 pvt. Antenna [aristal apical segment broken] brownish except scape and pedicel dark yellow; pedicel with black apical bristles; postpedicel elongated, 3.3 times longer than wide, basally rather thick, apically distingtly narrowed, with dense dark brown pubescence (Fig. 9). Proboscis short, brownish yellow with short yellow hairs; palpus small, dark yellow with short yellow hairs.
Thorax metallic green with pale gray pollinosity, but pleura blackish to black. Hairs and bristles on thorax black; 6 dc; 8 irregularly paired 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 [fore tarsus and hind tarsomeres 2–5 broken] mainly yellow; fore and hind coxae yellow, but mid coxa dark brown. Hairs and bristles on legs black. Fore coxa with dark yellow hairs and bristles; mid coxa with blackish hairs and bristles; hind coxa with dark yellow hairs and 1 black outer bristle at middle. Hind trochanter with 1 black bristle. Mid tibia with 1 very long ad, 3 pd (one is strong at the base, the other two are weak), and 2 apical bristles (one is strong, the other is weak). Hind tibia with 5 pd and 2 apical bristles. Mid tarsomeres 1–3 each with 1 av at middle, tarsomeres 1–4 each with 4 apical bristles. Relative length of tibiae and five tarsomeres of legs LI 3.5: distal podomeres missing; LII 4.2: 2.0: 1.5: 1.0: 0.6: 0.4; LIII 5.5: 1.2 distal podomeres missing
Wing nearly hyaline; veins dark brown; R 4+5 and M 1 widened at first, then convergent apically; CuAx ratio 0.4. Squama yellow with blackish hairs. Halter pale yellow.
Abdomen dark metallic green with pale gray pollinosity, venter dark yellow; tergum 1 brown, but dark yellow laterally; tergum 2 dark yellow at basal margin and lateral portion; tergum 3 dark yellow at anterolateral portion. Hairs and bristles on abdomen black.
Male genitalia (Fig. 10): epandrium longer than wide; epandrial lobe thick with weakly narrow tip; surstylus geniculate with a finger-like dorsal process near base and a short obtuse denticles at extreme tip. Cercus basally slightly thick, apically bifurcated with dorsal lobe slightly shorter than ventral lobe. Hypandrium long finger-like. Phallus slightly thick, but apically narrowed and bent.
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). PARATYPE: 1 ♂, same as holotype except, 2019.III.19–IV.19 (CAU).
Remarks. Systenus basiflavus sp. nov. is somewhat similar to S. digitatus sp. nov. in having the postpedicel distinctly elongated and surstylus elongated with a small dorsal process near base among Asian species, but can be easily separated from the latter by the following features: antennal scape and pedicel dark yellow; surstylus geniculate with a long finger-like dorsal process near base directed backward; cercus bifurcated apically.
Distribution. China (Yunnan).
Etymology. The specific name refers to the antenna dark yellow at base.
description: Published as part of Lin, Chen, Zhang, Chunmin & Yang, Ding, 2023, The genus Systenus Meigen, 1803 (Diptera: Dolichopodidae) from Yunnan, China, with descriptions of six new species, pp. 153-166 in Zootaxa 5383 (2) on pages 156-158, DOI: 10.11646/zootaxa.5383.2.3, http://zenodo.org/record/10350971