Two new species of Rhaphium from Qinghai Province, China (Diptera, Dolichopodidae, Rhaphiinae)

Abstract At present, there are 31 species of Rhaphium Meigen recorded in China. In this paper, two species from Qinghai Province of China are described as new to science: Rhaphium huzhuensesp. nov., Rhaphium minhensesp. nov. A key to the Chinese species of Rhaphium is provided.


Introduction
The genus Rhaphium Meigen belongs to the subfamily Rhaphiinae and contains 206 known species in the world (Yang et al. 2006;Yang et al. 2011;Grichanov 2017;Qilemoge et al. 2019;Grootaert 2019). Thirty-one species have been recorded in China, including 11 species distributed only in Oriental China, 17 species distributed only in Palaearctic China, two species from Oriental and Palaearctic China, and one species, R. dilatatum Wiedemann, 1830, with an unclear Chinese distribution (Yang et al. 2006;Qilemoge et al. 2019;Grootaert 2019).
The specimens upon which this study is based were collected in the Qinghai Province of China. The Qinghai Province is located in the northeastern part of the Tibetan First flagellomere about 2.0 times as long as wide; arista about 2.0 times longer than first flagellomere; fore femur with row of long pale yellow ventral bristles as long as width of fore femur; cercus narrowed at base and widened towards apex, with distinct marginal denticles (Yang et al. 2011: fig. 811 (Fig. 1). Body length 3.6-3.75 mm. Wing length 4.0-4.2 mm. Head metallic green with pale gray pruinescence. Face black with pale gray pruinescence. Frons brown with pale gray pruinescence. Upper postocular bristles black, middle and lower postocular bristles yellow. Two oc, two vt, two pvt. Antenna (Fig. 3) black; scape bare; pedicel with hairs; first flagellomere elongated, 7.5 times longer than wide, apically sharp; arista black, inserted at apex, basal aristomere 1/4 as long as apical aristomere. Proboscis and palpus black with yellow hairs.
Thorax metallic green with pale gray pruinescence. Hairs and bristles on thorax black. Four strong dc, four irregular pairs of acr, two strong npl, one strong sutural ial, two strong pa, one strong anterior pprn; scutellum with one pair of sc. Legs yellow, except for basal part of mid and hind coxae black; hind femur black dorsally near apex; fore and mid tarsi from tip of tarsomere 2 onwards black, tip of tarsomere 1 of fore and mid leg black, hind tarsus from tip of tarsomere 1 onward black. Most hairs and bristles on legs black, fore coxa with yellow bristles, and mid and hind coxae each with one black outer bristle. All femora without ventral bristles, mid and hind femora each with one black preapical bristle. Fore tibia with one ad, two pv, middle with one av, and two apical bristles; mid tibia with two ad, one pd, basal half with one av, and three apical bristles; hind tibia with two ad, two pd, three av (basal half with one av, apical half with two av), and three apical bristles. Relative lengths of femur, tibia and 5 tarsomeres, fore leg 2.6 : 2.8 : Abdomen metallic green with pale gray pruinescence with hairs and bristles black. Male genitalia (Fig. 4): epandrium black, nearly as long as wide. Epandrial lobe short, rounded apically, without distinct bristle. Surstylus on epandrium black, nearly triangular, outside margin with seven strong bristles and apex with four strong bristles. Cercus black, bifurcate, outer lobe long, slender, curved with strong bristles along length ventrally; inner lobe wider and shorter, strip-like, apically with three strong bristles.

Remarks.
The new species is similar to R. apicinigrum Yang & Saigusa, 1999, but these two species can be separated by several features. In R. huzhuense, the first flagellomere is about 7.5 times longer than wide (Fig. 3); the fore coxa is yellow, the mid and hind coxae are black with the yellow apex; the hind femur is black apico-dorsally; and the surstylus is nearly triangular, not bifurcated (Fig. 4). In R. apicinigrum, the first flagellomere is about 4.3 times longer than wide; all coxae are yellow; and the surstylus is long and apically bifurcated (Yang et al. 2011(Yang et al. : 1248 fig. 799a, b).
Etymology. The specific name refers to the type locality, Huzhu.
Thorax metallic green with pale gray pruinescence. Hairs and bristles on thorax black. Four strong dc, four irregular pairs of acr, two strong npl, one strong sutural ial, two strong pa, one strong anterior pprn; scutellum with one pair of sc. Legs black, except for fore and mid femora ventrally yellow at tip, hind femur ventrally yellow at basal 3/4. Most hairs and bristles on legs black. Fore and mid coxae with yellow bristles, hind coxa with one black outer bristle. Mid and hind femora each with one black preapical bristle. Fore tibia with one ad, one pd, basal half with two av, and two apical bristles; mid tibia with two ad, one pd, apical half with one av, and four apical bristles; hind tibia with two ad, two pd, three av (middle with one av, apical half with two av), and four apical bristles. Relative lengths of femur, tibia and 5 tarsomeres, fore leg 2.4 : 2.5 : 1.2 : 0.5 : 0.4 : 0.2 : 0.3; mid leg 3.1 : 3.0 : 1.6 : 0.7 : 0.5 : 0.4 : 0.4; hind leg 3.5 : 3.9 : 1.6 : 1.6 : 0.8 : 0.5 : 0.4. Wing hyaline, veins black; M bent medially, M and R 4+5 parallel apically; CuAx ratio 0.36. Calypteral fringe yellow with black hairs. Halter yellow.
Abdomen metallic green with pale gray pruinescence with hairs and bristles black. Male genitalia (Fig. 6): epandrium black, nearly as long as wide. Surstylus on epan-drium black, thin, finger-like, apically sharp, with two weak bristles, ventrally with one protuberance. Cercus bifurcate, outer lobe thick, twisted at middle, nearly triangular at apical half, apically with two long strong bristles; inner lobe strip-like, apically rounded, with three strong bristles, ventrally with five long strong bristles.

Remarks.
The new species is similar to R. shaliuhense Qilemoge et al., 2019, but both species can be separated by several features. In R. minhense, the body length is 4.0 mm; the thorax has four strong dc; the fore and mid femora are yellow ventrally at tip; the Calypteral fringe has black hairs; the outer lobe of cercus is twisted at middle, the apical half part is nearly triangular (Fig. 6). In R. shaliuhense, the body length is 2.5 mm; the thorax has five strong dc; the fore and mid femora are black; the Calypteral fringe has yellow hairs; the outer lobe of the cercus is strip-like (Qilemoge et al. 2019: 94, fig. 7).
Etymology. The specific name refers to the type locality, Minhe.

Discussion
Rhaphium is the largest genus in Rhaphiinae and including the species described here there are now 33 species documented to occur in China. Several species groups have been proposed within Rhaphium, for example Negrobov (1986) proposed a key to Palaearctic and Nearctic species of the R. nasutum group, having the following characters: hind coxa with a group of lateral hairs, fore tarsomere 1 with a row of short black bristles, cercus divided into lobes. Grichanov (2004) and Naglis (2009) mentioned the R. albifrons group, with the following combination of characters: hind coxa with a strong white lateral bristle; fore tarsomere 1 without comb of strong bristles; a key to males was provided. Negrobov and Grichanov (2010) described, and provided a key to, the R. crassipes group, diagnosed by: mid tarsomeres 4-5 black, dilated and flattened dorsoventrally. Naglis and Grootaert (2011) published the R. srilankensis group, with the sole nominal species notable for the arista being absent in males, and provided a key to Oriental genera of Rhaphiinae. Negrobov et al. (2011) proposed the R. tridactylum group, included four species, and provided a key to species. Negrobov et al. (2013) described the R. ensicorne group in which the cercus is bifoliate. Tang et al. (2016) mentioned the R. bilobum group with the defining characters: thorax with 5 dc; cercus bifurcate with two simple lobes and the R. flavilabre group, diagnosed by: thorax with 5 dc; male genitalia shorter than epandrium, with long pale apical bristles which are at least as long as epandrium. Grootaert et al. (2019) proposed the R. micans group, which differed by the following characters: cercus long, flattened, nearly twice as long as epandrium. The two new species described here do not fit the diagnoses of any of the above species groups. Previously, there were 31 species recorded from China. Here we report two new species of Rhaphium from the Qinghai Province of Palaearctic China. Rhaphium can be considered a widespread genus in China. However, Ningxia, Xinjiang and Shanxi have few species, which might be due to the relatively dry climates of these provinces. The sole species (R. heilongjiangense) was known from the northeastern provinces (Heilongjiang, Jilin, Liaoning) of China: inadequate collection might be another reason for lower species diversity (Yang et al. 2011).