Body small to large (1.5–5.7 mm); vertex flat; oc nearly as long as vt; face obviously narrower than frons; clypeus not obviously separate from face; antenna black, first flagellomere mostly prolonged, 2–10 times longer than wide, arista apical; propleuron with dense pale white hairs, without distinct bristle; hind coxa with or without 1 outer bristle at middle; vein M straight and not bifurcated, R₄₊₅ parallel or slightly convergent with M in wing apex, CuAx ratio less than 1; abdominal segments 1–3 usually with long pale hairs, abdominal segment 6 visible and pubescent; male genitalia connected tightly with pregenital segment, cap-like, cercus varied, often long and narrowed towards tip, sometimes bifurcate, with hairs and bristles at middle (Yang et al. 2011).

First flagellomere about 2.2 times longer than wide; arista with basal segment 0.1 times as long as apical segment. All postocular bristles black. All coxae and femora black; fore tibia mainly yellow, black dorsally, mid tibia yellow, hind tibia mainly black, yellow at middle dorsally; fore tarsomere 1 inflated apically. Fore and mid coxae with black bristles, mid coxa apically with a bunch of black bristles, hind coxa with one black outer bristle. CuAx ratio 0.5. Surstylus short and thick, nearly square, with one apical protuberance. Cercus bifoliate, outer lobe and inner lobe strip-like, inner lobe 1/4 as long as outer lobe, apically with strong bristles.

Male (Fig. 1). Body length 4.8 mm. Wing length 4.2 mm.

Head metallic green with pale gray pruinescence. Frons with white pruinescence. Face black with pale pruinescence, not as wide as first flagellomere (length). All postocular bristles black. Two oc, two vt, two pvt. Antenna (Fig. 4) black; first flagellomere elongated, about 2.2 times longer than wide, apically sharp; arista black, apical position, basal segment 0.1 times as long as apical segment. Proboscis black with black hairs, palpus black with black apical bristle and hairs.

Thorax metallic green with pale gray pruinescence. Mesonotum without dark spot. Hairs and bristles on thorax black. Five strong dc, four irregular pairs of acr, two strong npl, one strong sa, two strong pa; scutellum with two pairs of sc, medial pair pubescent, lateral pair strong.

Legs black, all coxae and femora black; fore tibia mainly yellow, black dorsally, mid tibia yellow, hind tibia mainly black,yellow dorsally at middle; fore tarsomere 1 inflated apically, fore and mid tarsi black from tip of tarsomere 2 onwards, hind tarsus entirely black. Hairs and bristles on legs black. Fore and mid coxae with bristles, mid coxa apically with a bunch of bristles, hind coxa with one outer bristle. All femora with ventral bristles, mid and hind femora each with one preapical bristle. Fore tibia with five ad, six pd, and four apical bristles, av absent,; mid tibia with two ad, five pd, three av, and four apical bristles; hind tibia with three ad, five pd, three av, and three apical bristles. Relative lengths of tibia and 5 tarsomeres of fore leg 2.5 : 1.2 : 0.7 : 0.4 : 0.3 : 0.4; mid leg 3.2 : 1.7 : 0.8 : 0.6 : 0.5 : 0.4; hind leg 4.3 : 1.3 : 1.2 : 0.8 : 0.5 : 0.4. Wing hyaline, veins black; M bent medially, M and R₄₊₅ parallel apically; CuAx ratio 0.5. Squama yellow with yellow hairs. Halter yellow.

Abdomen entirely metallic green with pale gray pruinescence. Hairs and bristles on abdomen black. Male genitalia (Fig. 5): epandrium black, nearly as long as wide. Surstylus black, short and thick, nearly square, with one apical protuberance. Cercus yellow, bifoliate, outer lobe and inner lobe strip-like, inner lobe 1/4 as long as outer lobe, both lobes with short bristles.

Female. Unknown.

Holotype male, CHINA, Qinghai, Gangchaxian, Shaliuhe, 3,200 m; collected by sweep net in grassland, 2015.VIII.06, leg. Liang Wang. Paratypes: one male, same data as holotype.

Palaearctic: China (Qinghai).

The new species is somewhat similar to R. heilongjiangense Wang, Yang & Masunaga, 2005, but the two species can be separated by several features. In R. gangchanum, all postocular bristles are black, the thorax has five dc, and the mid femur is black (Fig. 1), the cercus is bifoliate (Fig. 5). In R. heilongjiangense, the middle and lower postocular bristles are yellow, the thorax has eight dc, the mid femur is yellow, the cercus is not bifoliate (Yang et al. 2011: 1255, fig. 804).

The specific name refers to the type locality, Gangcha.

First flagellomere much elongated, about 7.0 times longer than wide; arista basal segment 0.5 times as long as apical segment. All coxae black, all femora mainly black except hind femur yellow ventrally at base. Fore and mid coxae with yellow bristles, mid coxa apically with a bunch of yellow bristles, hind coxa with one yellow outer bristle. CuAx ratio 0.4. Surstylus finger-like, curved apically and rounded, without distinct bristle. Cercus bifoliate, outer lobe strip-like; inner lobe thick, strip-like, apically with three long and strong bristles.

Male (Fig. 3). Body length 2.5 mm. Wing length 2.7 mm.

Head metallic green with pale gray pruinescence. Frons with white pruinescence. Face black with pale pruinescence, not as wide as first flagellomere (length). Upper postocular bristles black, middle and lower postocular bristles yellow. Two oc, two vt, two pvt. Antenna (Fig. 6) black; first flagellomere elongated, about 7.0 times longer than wide, apically sharp; arista black, apical position, basal segment 0.5 times as long as apical segment. Proboscis brown with yellow hairs. Palpus brown with black apical bristle and hairs.

Thorax metallic green with pale gray pruinescence. Mesonotum without dark spot. Hairs and bristles on thorax black. Five strong dc, four irregular pairs of acr, two strong npl, one strong sa, two strong pa; scutellum with two pairs of sc, medial pair pubescent, lateral pair strong.

Legs black; all coxae black, all femora mainly black except hind femur yellow ventrally at base. Hairs and bristles on legs black. Fore and mid coxa with yellow bristles, mid coxa apically with a bunch of yellow bristles, hind coxa with one yellow outer bristle. Mid and hind femora each with one preapical bristle. Fore tibia with one ad, one pd, one av, and two apical bristles; mid tibia with two ad, two pd, one av, and three apical bristles; hind tibia with three ad, four pd, two av, and four apical bristles. Relative lengths of tibia and 5 tarsomeres of fore leg 2.7 : 1.4 : 0.6 : 0.5 : 0.3 : 0.4; mid leg 4.0 : 2.1 : 1.0 : 0.5 : 0.4 : 0.5; hind leg 5.0 : 1.5 : 1.3 : 1.0 : 0.6 : 0.5. Wing hyaline, veins black; M bent medially, M and R₄₊₅ parallel apically; CuAx ratio 0.4. Squama yellow with yellow hairs. Halter yellow.

Abdomen entirely metallic green with pale gray pruinescence. Hairs and bristles on abdomen black. Male genitalia (Fig. 7): epandrium black, nearly as long as wide. Surstylus finger-like, curved apically and rounded, without distinct bristle. Cercus bifoliate, outer lobe strip-like, apically with long strong bristles; inner lobe thick, strip-like, apically with three long strong bristles.

Female. Unknown.

Holotype male, CHINA, Qinghai, Gangchaxian, Shaliuhe, 3,200 m, collected by sweep net in grassland, 2015.VIII.06, leg. Liang Wang.

Palaearctic: China (Qinghai).

The new species is somewhat similar to R. daqinggouense Tang, Wang & Yang, 2016, but the two species can be separated by several features. In R. shaliuhense, there are four pairs of acr, all coxae are black, and the surstylus is finger-like, curved apically (Fig. 7). In R. daqinggouense, there are eight pairs of acr, the all coxae are yellow, except mid coxa is black at basal half, the surstylus is oblanceolate, not curved apically (Tang et al. 2016: 587, fig. 14).

The specific name refers to the type locality, Shaliuhe.

Figures 1–3. 

Habitus, lateral view. 1 Rhaphium gangchanum sp. n. male 2 Rhaphium tianshuiense sp. n., male 3 Rhaphium shaliuhense sp. n., male. Scale bars: 1 mm.

Figures 4–7. 

Rhaphium gangchanum sp. n., male 4 antenna, lateral view 5 genitalia, lateral view. Rhaphium shaliuhense sp. n., male 6 antenna, lateral view 7 genitalia, lateral view. Abbreviations: sur = surstylus, cer (o) = outer lobe of cercus, cer (i) = inner lobe of cercus. Scale bars: 0.2 mm.

First flagellomere about 1.8 times longer than wide; arista with basal segment 0.1 times as long as apical segment. Legs mainly yellow; fore coxa mainly yellow, black basally, mid and hind coxae mainly black, yellow apically; fore femur black dorsally, hind femur black apically; hind tarsus entirely black. Fore coxa with two black bristles, mid coxa with one black bristle at apical half, apically with a bunch of black bristles, hind coxa with one black outer bristle. CuAx ratio 0.52. Surstylus basally thick, apically sharp, with one protuberance. Cercus bifoliate, outer lobe long strip-like, apical curlily with one long strong bristle; inner lobe short, 1/4 as long as outer lobe.

Male (Fig. 2). Body length 3.8–4.0 mm. Wing length 3.1–3.3 mm.

Head metallic green with pale gray pruinescence. Frons with white pruinescence. Face dark metallic green with silvery white pruinescence, not as wide as first flagellomere (length). Upper postocular bristles black, middle and lower postocular bristles yellow. Two oc, two vt, two pvt. Antenna (Fig. 8) black; first flagellomere elongated, about 1.8 times longer than wide, apically sharp; arista black, apical position, basal segment 0.1 times as long as apical segment. Proboscis black with black hairs, palpus black with black apical bristle and hairs.

Thorax metallic green with pale gray pruinescence. Mesonotum without dark spot. Hairs and bristles on thorax black. Five strong dc, four irregular pairs of acr, two strong npl, one strong sa, two strong pa; scutellum with two pairs of sc, medial pair pubescent, lateral pair strong.

Legs mainly yellow; fore coxa mainly yellow, black basally, mid and hind coxae mainly black, yellow apically; fore femur black dorsally, hind femur black apically; fore tarsus black from tip of tarsomere 2 onwards, mid tarsus from tip of tarsomere 3 onward black, hind tarsus entirely black. Hairs and bristles on legs black. Fore coxa with two bristles, mid coxa with one black bristle at apical half, apically with a bunch of black bristles, hind coxa with one black outer bristle. Mid and hind femora each with one black preapical bristle. Fore tibia with two ad, three pd, and two apical bristles, av absent,; mid tibia with three ad, four pd, one av, and three apical bristles; hind tibia with two ad, three pd, and three apical bristles, av absent. Relative lengths of tibia and 5 tarsomeres of fore leg 2.2 : 1.3 : 1.2 : 0.5 : 0.5 : 0.3; mid leg 3.2 : 1.7 : 1.0 : 0.7 : 0.5 : 0.3; hind leg 4.2 : 1.2 : 1.3 : 1.0 : 0.7 : 0.4. Wing hyaline, veins black; M bent medially, M and R₄₊₅ parallel apically; CuAx ratio 0.52. Squama yellow with black hairs. Halter yellow.

Abdomen entirely metallic green with pale gray pruinescence. Hairs and bristles on abdomen black. Male genitalia (Fig. 9): epandrium black, nearly as long as wide. Surstylus yellow, basally thick, apically sharp, with one protuberance, without distinct bristles. Cercus bifoliate, outer lobe long strip-like, curled apically with one long strong bristle; inner lobe short, 1/4 as long as outer lobe, apically sharp with strong bristles.

Female. Unknown.

Holotype male, CHINA, Gansu, Tianshui, Maiji Mountain, 1,396 m, collected by sweep net in grassland, 2012.VII.16, leg. Zehui Kang. Paratypes: two males, same data as holotype; four males, Beijing, Miyunxian, Caojialucun, 561 m, collected by sweep net in grassland, 2013.V.23, leg. Xunkun Li.

Palaearctic: China (Gansu, Beijing).

The new species is similar to R. mediocre (Becker, 1922), but the two species can be separated by several features. In R. tianshuiense, the squama with black hairs, the surstylus is basally thick, apically sharp, has one protuberance and the cercus is bifoliate (Fig. 9). In R. mediocre, the squama with yellow hairs, the surstylus is short and thick, the cercus is not bifoliate (Yang et al. 2011: 1258, fig. 806).

The specific name refers to the type locality, Tianshui.

Figures 8, 9. 

Rhaphium tianshuiense sp. n., male 8 antenna, lateral view 9 Genitalia, lateral view. Abbreviations: sur = surstylus, cer (o) = outer lobe of cercus, cer (i) = inner lobe of cercus. Scale bars: 0.2 mm.