Hercostomus triangulatus, Qian & Wang & Yang, 2022

Qian, Xingyang, Wang, Ning & Yang, Ding, 2022, The genus Hercostomus Loew (Diptera, Dolichopodidae, Dolichopodinae) from Inner Mongolia, China, with the description of two new species, ZooKeys 1118, pp. 119-131 : 119

Hercostomus triangulatus sp. nov.

Figs 8 , 12-14

Diagnosis.

Antenna mainly dark yellow; postpedicel blackish with basal ventral surface dark yellow, 1.2 times longer than wide, obtuse at tip; arista black, basal segment 0.25 times as long as apical segment. All coxae dark yellow. Male cercus nearly triangular with weak denticles and 3 relatively long finger-like processes.

Description.

Male (Fig. 8 ). Body length 3.7-4.1 mm, wing length 3.3-3.6 mm.

Head metallic green with dense pale grey pollinosity. Hairs and bristles on head black, middle and lower postocular bristles and posteroventral hairs yellow. Antenna (Fig. 12 ) dark yellow except scape blackish at base and postpedicel blackish with base and ventral surface dark yellow; postpedicel 1.2 times longer than wide, somewhat acute at tip; arista blackish with short pubescence, basal segment 0.25 times as long as apical segment. Proboscis brownish yellow with black hairs; palpus brownish, with dark yellow hairs and 1 dark yellow apical bristle.

Thorax metallic green with pale grey pollinosity. Hairs and bristles on thorax black; 6~8 irregularly biseriate acr short hair-like; 6 long strong dc. Scutellum with 2 pairs of sc, basal pair short hair-like. Propleuron with yellowish hairs and 1 black bristle on lower portion.

Legs yellow; all coxae yellow; all tarsi brown to dark brown from tip of tarsomere 1 onwards. Hairs and bristles on legs black; mid and hind coxae each with 1 outer bristle; mid and hind femora each with 1 preapical bristle; fore tibia with 1 ad, 2 pd and 2 short apical bristles; mid tibia with 4 ad, 2 short pd, 1 av and 4 short apical bristles; hind tibia with 3 ad, 3 pd, 4 short av (2 inner bristles thin, 2 outer bristles thick) and 3 apical bristles. Hind tarsomere 1 with 1 short ventral bristle at base. Relative lengths of tibia and 5 tarsomeres of legs LI: 2.0: 1.1: 0.5: 0.4: 0.3: 0.2; LII: 2.8: 1.5: 0.8: 0.7: 0.4: 0.3; LIII: 3.4: 1.0: 1.2: 0.5:?:?. Wing nearly hyaline, veins dark brown; R4+5 and M distinctly convergent apically; CuAx 0.5. Squama yellow with dark yellowish hairs. Halter yellow.

Abdomen metallic green with pale grey pollinosity. Hairs and bristles on abdomen black; tergite 1 with several short yellow hairs; sternites 2-3 with short yellow hairs. Male genitalia (Fig. 14 ): Epandrium distinctly longer than wide, narrowed at tip; epandrial lateral lobe relatively short and thick. Subepandrial process (Fig. 13 ) with two processes separated, narrowed at tip. Male cercus nearly triangular with some weak denticles and 3 relatively long finger-like processes bearing long bristles on apical margin. Hypandrium somewhat acute at tip.

Female. Body length 3.0-3.6 mm, wing length 3.6-3.7 mm.

Type material examined.

Holotype: male, China, Inner Mongolia, Tongliao, Daqinggou, 180m, 2014.VII.24, Ning Wang & Ding Yang (CAU). Paratypes: 3 males 1 female, same data as holotype (CAU); 8 males 3 females, China, Inner Mongolia, Tongliao, Daqinggou, 180 m, 2014.VII.23, Ning Wang & Ding Yang (CAU); 1 male 1 female, China, Tongliao, Daqinggou, 180 m, 2014.VII.22, Ning Wang & Ding Yang (CAU).

Distribution.

China (Inner Mongolia).

Remarks.

The new species is somewhat similar to the members of H. crassivena group, but the veins of H. triangulatus are not thickened ( Zhang and Yang 2007).

Etymology.

This species is named after the triangular cercus.

Figures

Figures 6 - 8. Habitus, lateral view 6 Hercostomus shennongjiensis Yang, 1997, male 7 Hercostomus sinicus Stackelberg, 1934, male 8 Hercostomus triangulatus sp. nov., holotype male. Scale bars: 1 mm.

Figures 12 - 14. Hercostomus triangulatus sp. nov., male 12 antenna, lateral view 13 subepandrial processess and postgonite, lateral view 14 genitalia, lateral view. Abbreviations: hyp = hypandrium, epan = epandrial lobe, cer = cercus. Scale bars: 0.1 mm.