Chrysotus pallidus, Wei, Lianmeng & Zhang, Lili, 2010

Wei, Lianmeng & Zhang, Lili, 2010, A taxonomic study on Chrysotus Meigen (Diptera: Dolichopodidae) from southwest China: descriptions of eleven new species belonging to the redefined C. laesus - group, Zootaxa 2683, pp. 1-22 : 16-18

9. Chrysotus pallidus sp. nov.

( Fig. 9 )

Diagnosis. Face wider, narrowed below, at the lowest portion about as wide as first flagellomere. Postocular setae and occiput with setae pale. Proboscis blackish brown, palpus blackish brown. All coxae and femora metallic blue green, base of tibiae not brown. Squama pale with pale setulae. Halter pale. Male terminalia with ventral projection of epandrium with end flattened, remarkably withdrawn to level of distal margin of lateral epandrial lobe. Lateral epandrial lobe in form of equilateral triangle. Cercus longer oval. Hypandrium with enlarged apical part in a closed loop, denticulated marginally.

Description. Male: Body length 2.75 mm, wing length 2.25 mm. Head: Metallic dark green with pale gray pollinosity. Face wider, narrowed below, at lowest portion about as wide as first flagellomere. Setulae and setae on head black, postocular setae and occiput with setae pale. Antenna black; first flagellomere nearly rectangular, about 0.5 times as long as width ( Fig. 9 B). Proboscis blackish brown with black setulae; palpus blackish brown with 1 black apical seta. Thorax: Dark metallic violet green with dense brown pollinosity. Setulae and setae on thorax black; 6 dc, only hind 5 strong; 14 irregularly paired acr short and setula-like; scutellum with 2 pairs of setae, basal pair short and setula-like; propleuron with 1 pale setula and 1 pale seta on lower part. Legs: Yellow, all coxae, trochanters and femora metallic dark blue green, but latter with yellow apex; base of tibiae not brown, all tarsus from tip of tarsomere 1 onwards dark yellow to blackish brown. Setulae and setae on legs black, except setae on anterior face of fore coxae white. Mid and hind coxae each with 1 outer seta. Fore femur with 5 pv apically, mid femur with 5 posterior and 5 pv apically, former stronger than latter, hind femur with 3 av apically. Fore tibia without setae, apically with 3 short setae; mid tibia without setae (MSSC), apically with 4 setae, dorsal 2 short and weak; hind tibia with 1 ad and 3 pd, apically with 3 short setae. Relative lengths of tibia and 5 tarsomeres of legs LI 78: 40: 16: 10: 7: 10; LII 90: 43: 19: 12: 7: 9; LIII 90: 30: 20: 12: 8: 10. Wing: Hyaline, veins brown; R4+5 and M1+2 slightly divergent apically, CuAx ratio 0.4. Squama pale with pale setulae. Halter pale. Abdomen: Metallic greenish violet with thin brown pollinosity; setulae and setae on abdomen black. Male terminalia ( Fig. 9 A). Epandrium with angular projection posteriorly. Ventral projection of epandrium with end flattened, and remarkably withdrawn back to level of distal margin of lateral epandrial lobe. Lateral epandrial lobe is equilateral triangle, bearing short seta. Surstylus somewhat long and slightly curved. Cercus longer oval, with strong setae. Hypandrium with enlarged apical part in closed loop, denticulated marginally. Proximal portion of hypandrium with projection. Postgonite with strip-like arms and anterior process, former acute apically and latter rounded distally, and hidden deeply in epandrium. Female: Body length 2.3 mm, wing length 2.2 mm. Similar to male, but face wider than in male. Mid tibia with 1 ad near base; hind tibia with 2 ad and 4 pd (upper 1 pd as weak as setula). Relative lengths of tibia and 5 tarsomeres of legs LI 78: 40: 16: 9: 7:?; LII 90: 50: 20: 10: 10: 8; LIII 98: 30: 22: 13: 10: 10. Terminalia ( Figs. 9 C-D). In ventral profile: Tg6–7 with deep inverted U-shaped incisions; Tg8 divided into pair of rod-like sclerites, every one with short long triangular sclerite on inner margin mesally, very weakly sclerotized; Tg9 retrogressive; acanthophorites (Tg10) divided into two sclerites, each on dorsal surface with crest of 3 dull spines; posterior margin of St5 almost flat; St6 weakly sclerotized posteriorly, long pentagon with shallow inverted U-shaped incision; St7 long trapezoidal, with sclerotized narrow bands along two lateral sides, anterior margin of which almost flat, and posterior margin entirely flat, each of two posterior angles with rather long and narrow strip-shape projection; St8 divided into pair of rodlike sclerites, connected anteriorly by sclerotized bridge; St10 long and curved stick, enlarged apically, covered with setulae. In profile: both Tg8 and St8 touch each other anteriorly; Tg10 nearly rectangular; St8 with pair of angular processes apically; St9 nearly meniscus-like, pointed apically, with two rows of spinulae, densely with longer setae distally; St10 long straight stick-like, somewhat contracted basally, with setulae and group of long setae apically; cercus longer and narrower knife-like, distal part with developed seta and short seta, apical ventral side pale and setulose.

Type material. HOLOTYPE ɗ, Guizhou: Zhenning, Bahe, 1100 m, 25º45’N, 105º52.5’E, 28.VI.2008, LM Wei, SG Jiang, WP Chao, MH Liu and QL Xiao. PARATYPES: 5 ɗ, 1 Ψ same as holotype; 2 ɗ, 13 Ψ, Guizhou: Qianxi, Bailidujuan, 1700-1800m, 27º10’N, 105º26’E, 17-18.VII.2010, LM Wei, WP Chao, Biao Long, Kun Du, QD Wang and Hua Wang.

Etymology. From the Greek pallidus “pale”, meaning postocular setae and occiput pale.

Remarks. Based on the key of Becker (1922), the new species will run to couplet 3, but differs from all species under the couplet by blackish brown femora and yellowish brown tibiae.

According to the key of Negrobov et al. (2000), the new species will run to C. nudisetus Negrobov et Maslova, 1995 , but can be easily separated from the latter by male eyes separated widely on face and the structural features of the male terminalia.

Figures

FIGURE 9. Chrysotus pallidus sp. nov. (A) male terminalia, left lateral view; (B) male first flagellomere, lateral view; (C-D) female terminalia (C, dorsal view; D. lateral view). Abbreviations: cerc, cercus; St, sternite; Tg, tergite.