Rhaphium bisectum, Tang, Chufei, Wang, Ning & Yang, Ding, 2016

Tang, Chufei, Wang, Ning & Yang, Ding, 2016, Rhaphium (Diptera: Dolichopodidae: Rhaphiinae) from China with six new species, Zootaxa 4162 (3), pp. 581-593 : 588

Rhaphium bisectum sp. nov.

( Figs 3 , 11–12 )

Diagnosis. First flagellomere twice longer than wide; arista black, twice as long as first flagellomere ( Fig. 11 ). 5 dc; 5–8 pairs of short irregular acr. Cercus bifurcated near base, with 3 long strong pale marginal bristles; ventral lobe bifurcated at apical 1/4; with long strong pale apical bristles ( Fig. 12 ).

Description. Male ( Fig. 3 ). Body length 2.7 mm, wing length 2.2mm. Head: Frons metallic green with grey white pollinosity; face dark metallic green with thick silvery white pollinosity, nearly as wide as first flagellomere; palpus and proboscis black with black hair, palpus with 1 black apical bristle; bristles and hairs on head black except postocular bristles and posteroventral hairs pale yellow; antenna black; first flagellomere nearly isosceles triangular, somewhat elongated, rounded at tip, twice longer than wide; arista apical, simple, twice as long as first flagellomere. Thorax metallic green with grey white pollinosity; propleuron covered by short pale yellow bristles; hairs and bristles strong and black; 5 strong dc; 5–8 pairs of short irregular acr, median sc normal, lateral sc weak and short. Legs mainly yellow except basal half of fore and mid coxae and entire hind coxa black, apical 1/3 of hind femur with black spot, fore and mid tarsi light brown, hind tarsus black. Hairs and bristles black except hairs on fore coxa. Fore coxa with pale yellow hairs dorsally and 1 thin bristle apically; mid coxa with 1 strong outer bristle at middle; hind coxa with 1 outer bristle at middle; bristles on coxae all black. Fore tibia with 3 thin ad; mid tibia with 2 ad and 2 pd; hind tibia with 2 ad, 2 pd and 4 apical bristles. Relative length ratio from tibia to tarsomere 5: LI: 3.0/1.5/1.6/0.5/0.2/0.3, LII: 4.0/2.5/1.2/0.8/0.5/0.4, LIII: 3.5/1.0/?/?/?/? (hind tarsus broken). Wing hyaline, somewhat grey; veins dark brown, R4+5 and M somewhat convergent apically; CuAx ratio 0.35. Squama yellow, with fan of pale white bristles; halter yellow. Abdomen metallic green with grey white pollinosity. Bristles and hairs black. Segments 1–5 with pale yellow hairs laterally, sternites 1–4 with pale yellow hairs ventrally. Male genitalia ( Fig. 12 ): epandrium slightly longer than wide. Surstylus irregular, with 1 long digitiform process which inflated at tip, with 2 small ventral processes. Cercus bifurcated near base, with 3 long strong pale marginal bristles; ventral lobe bifurcated at apical 1/4, with long strong pale apical bristles. Hypandrium and phallus simple. Female. Unknown.

Type material. HOLOTYPE, Ƌ labeled: China: Inner Mongolia, Daqinggou, Primeval forest (N42°82′18″ E122°17′41″), 180 m, collected by sweeping net in grass and brushes, 2014. VII.23, N. Wang & D. Yang ( CAU).

Distribution. Palaearctic: China (Inner Mongolia).

Remarks. The new species is somewhat similar to R. gansuanum Yang, 1998 from Gansu province of China, but may be separated from the latter by the length / width ratio of the first flagellomere, the color of the legs and the shape of the cercus. In R. gansuanum , the first flagellomere is 1.6 times longer than wide; the legs are mainly black but with yellow tibiae; the cercus is thin and long with the inflated base ( Yang et al. 2011).

Etymology. The word ‘ bisectum’ means being bifurcated twice. The new species is named after the shape of cercus.

Figures

FIGURE 1 – 6. 1. Rhaphium apophysatum sp. nov.; 2. R. bilobum sp. nov.; 3. R. bisectum sp. nov.; 4. R. daqinggouense sp. nov.; 5. R. dorsiseta sp. nov.; 6. R. neimengense sp. nov. All male. Scale bar = 1.0 mm.

FIGURES 11 – 12. Rhaphium bisectum sp. nov., male. 11. Antenna, scale bar = 0.2 mm; 12. Male genitalia, lateral view, scale bar = 0.2 mm. Abbreviations: hyp = hypandrium, epl = epandrial lobe, sur = surstylus, cer = cercus.