Three new species of Rhaphium from China, with an updated key to Chinese Rhaphium (Diptera, Dolichopodidae, Rhaphiinae)

Abstract At present, there are 26 species in the genus Rhaphium Meigen known from China. In this paper, three species from China are described as new to science: Rhaphiumgangchanumsp. n., Rhaphiumshaliuhensesp. n., and Rhaphiumtianshuiensesp. n. A key to the Chinese species of Rhaphium is provided.


Introduction
The genus Rhaphium Meigen belongs to the subfamily Rhaphiinae (Dolichopodidae) with 199 known species worldwide (Yang et al. 2006(Yang et al. , 2011Grichanov 2017). Twenty-six species have been recorded from China, with nine species only from Oriental China, 14 species only from Palaearctic China, two species from Oriental and Palaearctic China, and R. dilatatum Wiedemann, 1830 with an unclear Chinese distribution.
The specimens upon which this study is based were collected in Beijing as well as the Hebei, Qinghai, and Gansu regions of China. Gansu and Qinghai Provinces are located in northwestern China. Gansu Province has a temperate monsoon climate and lies between the Tibetan Plateau and the Loess Plateau. Qinghai Province has a plateau continental climate and is located in the northeastern part of the Tibetan Plateau. Beijing, the capital of China, is located in the north of the country and has a subtemperate climate. Hebei Province is also in the north, and its the climate is similar to that of Beijing. In the present paper, we describe three new species of the fauna of China and provide a key to all species of Chinese Rhaphium, except for R. dilatatum Wiedemann, 1830 and R. relates (Becker, 1922) because they are poorly described and the whereabouts of the holotypes are unknown.
Diagnosis. 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, R 4+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).

1
First flagellomere at least 4.0 times longer than wide (Fig. 6)  First flagellomere at most 7.0 times longer than wide (Fig. 6) (Fig. 9)  Diagnosis. 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 striplike, inner lobe 1/4 as long as outer lobe, apically with strong bristles. Description. 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. 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.

Distribution. Palaearctic: China (Qinghai).
Remarks. 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(Yang et al. : 1255 fig. 804).
Etymology. The specific name refers to the type locality, Gangcha.

Rhaphium shaliuhense sp. n.
http://zoobank.org/623CD00A-D4C1-44E2-9C60-A21AF345A650 Figures 3, 6, 7 Diagnosis. 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. Description. 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.
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. 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).
Etymology. The specific name refers to the type locality, Shaliuhe.
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.
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.   (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(Yang et al. : 1258 fig. 806).
Etymology. The specific name refers to the type locality, Tianshui.

Discussion
Rhaphium is quite a large genus in Dolichopodidae. Negrobov (1986) proposed a key to Palaearctic and Nearctic species of the R. nasutum group. Grichanov (2004) and Naglis (2009) mentioned the R. albifrons group. Negrobov and Grichanov (2010) published on the R. crassipes group. Naglis and Grootaert (2011) published the R. srilankensis group. In having the frons usually with white grey pruinosity, the hind coxa with a strong yellow outer bristle, the fore coxa without a comb of strong bristles, and the cercus usually bifoliated, R. shaliuhense sp. n. is included the R. albifrons group. The other two new species described in this paper do not match the diagnosis of any known group. As mentioned, there are 16 species previously recorded from Palaearctic China, and the three new species are all distributed in Palaearctic China. Rhaphium gangchanum sp. n. and R. shaliuhense sp. n. are collected from Qinghai province, and R. tianshuiense sp. n. is recorded from Gansu Province and Beijing City. Rhaphium can be considered a widespread genus in China (Fig. 10). However, Xinjiang, Xizang, and Inner Mongolia have few species, which might be because of the relatively dry climates of these three provinces. Inadequate collection might be another reason. check our English and for giving us valuable advice. This project was supported by National Natural Science Foundation of China (31672326), the Project of International Cooperation of Ministry of Agricultural, China (2016-X48), and the key project of Science-technology basic condition platform from the Ministry of Science and Technology of China (No.2005DKA21402).