Review of the genus Chrysotimus Loew from Tibet (Diptera, Dolichopodidae)

Abstract A review of the species of the genus Chrysotimus from Tibet is provided. The following four species are described as new to science: C. motuoensis sp. n., C. tibetensis sp. n., C. xuankuni sp. n., C. zhui sp. n. A key to the eight Tibetan species is presented.


Introduction
The genus Chrysotimus Loew, 1857 belongs to the subfamily Peloropeodinae with following characters: often yellow or yellowish hairs and bristles, small first flagellomere, posterior mesonotum distinctly flattened, wing length usually distinctly longer than body length, femora II and III each with strong anterior preapical bristles, most males with hind tarsomere 1 bearing several short black ventral bristles at base, and males with mid tarsomere 1 at least as long as the total of corresponding tarsomeres 2-4, hypopygium with 1-2 epandrial bristles (not processes) for most Chinese species. The genus is distributed worldwide except for the Afrotropical region with 70 known species, of which 14 species are known from the Palaearctic (Negrobov 1978(Negrobov , 1991, and 27 species from the Oriental (Dyte 1975;Yang et al. 2011, Wang et al. 2012). Thirty-seven species are known from China including those newly described herein. Guzeriplia Negrobov, 1968, embodies the characters of Chrysotimus Loew in the head and thorax with the yellow hairs and bristles and biseriate acr, though it has large hypopygium and a long surstylus and long cercus. For these reasons, it was synonymized with Chrysotimus by Yang et al. (2006).
Tibet, together with the Qinghai-Xizang Plateau, Hengduan Mountains, the Himalayas and the Yarlung Zangbo River, is considered to be the one of the most active geological regions and the most sensitive and richest regions in biological diversity in Southeast Asia. Furthermore, southeastern Tibet, bordered by tropical and monsoon rainforest, provides diverse habitats for numerous Oriental insect species, a large number of which are endemic to this area. So, it is likely that more Dolichopodidae and other dipterans will be discovered in the future in this area.
All the specimens in this study were collected from the Oriental part of southeastern Tibet. Four new species are described and a key to the species of Chrysotimus from Tibet is presented.

Materials and Methods
Specimens were studied and illustrated with a ZEISS Stemi 2000-c stereo microscope. Genitalic preparations were made by macerating the apical portion of the abdomen in warm 10% NaOH for 17-20 min. After examination and drawing the hypopygium, it was transferred to 75% alcohol and stored in a microvial pinned below the specimen. All specimens are deposited in the Entomological Museum of China Agricultural University (EMCAU), Beijing, China.  Loew, 1861, des. Coquillett (1910. Guzeriplia Negrobov, 1968: 470. Type species: Guzeriplia chlorina Negrobov, 1968. Tarsomere III1 with more than 10 black ventral bristles on basal 1/6; epandrium with wide lateral process (Fig. 8)  Tarsomere II1 longer than total length of tarsomere II2-5; Tarsomere III1 with 4-6 black ventral bristles at base; cercus long and thick with long bristles (Fig. 12) Diagnosis. All coxae yellow. 6-7 irregularly paired acr short and hair-like. Tarsomere III1 with group of 10-12 short black ventral bristles on basal 1/5, and row of 8-9 pv. Cercus bifurcated. For a full description of this species, see Wang and Yang (2006). Specimens examined. Type holotype, ♂, Tibet: Bomi, alt. 3050m, 1978.VII.16, leg. Fasheng Li. This specimen was collected from the subtropical rainforest with a sweep net and is deposited in EMCAU.

Chrysotimus grandis
Distribution. Tibet (Bomi). Diagnosis. First flagellomere subtriangular, as long as wide. Tarsomere III1 with group of 10-11 short black ventral bristles on basal 1/6. For a full description of this species, see Wang and Yang (2006 Diagnosis. Palpus pale yellow. First flagellomere short, about 1.5 times wider than long. Tarsomere III1 with group of about 13 short black ventral bristles on basal 1/6. For a full description of this species, see Wang and Yang (2006). Specimens examined. Type holotype, ♂, Tibet : Linzhi, alt. 3050m, 1978.VI.1-3, leg. Fasheng Li. This specimen was collected from the monsoon rainforest with a sweep net and is deposited in EMCAU.

Chrysotimus lii
Distribution. Tibet (Linzhi).   Diagnosis. Antenna yellow, with both pedicel and 1st flagellomere both with brown dorsal surface; acr absent; abdomen with tergites brilliantly metallic green dorsally and yellow laterally, and with yellow sternites; tarsomere III1 without black ventral spinelike bristles at base. Dexcription. Male. Body length 1.9 mm, wing length 1.9 mm. Head metallic green with gray pollen; frons and face brilliant; eyes separated distinctly; face wide and slightly narrower towards clypeus. Hairs and bristles yellow. Ocellar tubercle weak, with 2 very long oc and 2 very short posterior hairs. Lower  postocular bristles (including ventral hairs) pale. Antenna yellow, with both pedicel and 1st flagellomere with brown dorsal surface; first flagellomere ( Fig. 9) rather short, about 0.6 times as long as wide; arista apical, with basal segment very short. Proboscis brown, with pale hairs; palpus pale yellow, with pale hairs and 2 brown apical bristles.
Thorax metallic green with pale gray pollen, with pleura yellow. Hairs and bristles yellow; 6 dc, acr absent; scutellum with 2 pairs of bristles. Propleuron with 1 pale bristle on lower part. Legs including coxae yellow with 5th tarsomeres brown. Hairs and bristles on legs pale yellow; coxa I with 3-4 anterior and apical bristles, coxa II with 2 anterior and apical bristles, coxa III with 1 brown outer bristle near middle. Femora II and III each with 1 apical av. Tibia II with 2 ad and 2 pd, apically with 3 bristles; tibia III with 1 ad and 2 pd, apically with 3 bristles. All tarsomere 1 each with row of v. Tarsomere III 1 without black ventral spine-like bristles at base. Relative lengths of tibia and 5 tarsomeres of legs. Abdomen metallic green with pale gray pollen, tergites brilliant, sternites and lateral portion yellow. Hairs and bristles on tergites dark brown, and pale yellow on sternites.
Female. Body length 1.8 mm, wing length 1.7 mm. Similar to male, but antenna entirely yellow.
Distribution. Known only from the type locality in Tibet.
Remarks. This new species is similar to Chrysotimus guangxiensis Yang & Saigusa, but may be separated from the latter by brown proboscis, pale yellow palpus, and the tergites metallic green, sternites and lateral portion yellow. In guangxiensis, it has yellow proboscis, brown palpus, and whole abdomen metallic green (Yang and Saigusa 2001).
Etymology. The specific epithet derives from the type locality Motuo (Tibet).
Head metallic green with gray pollen; frons and face brilliant; eyes separated distinctly. Hairs and bristles on head yellow. Ocellar tubercle weak, with 2 very long oc and 2 very short posterior hairs. Lower postocular bristles (including ventral hairs) pale. Antenna (Fig. 11) brown; first flagellomere with round apex, rather short, about 0.6 times as long as wide; arista dorsal, with basal segment very short. Proboscis brown, with pale hairs; palpus pale yellow, with pale hairs and 2 brown apical bristles.
Thorax metallic green with pale gray pollen, mesonotum and scutellum brilliant. Hairs and bristles on thorax yellow; 6 dc, 5-6 irregular paired acr; scutellum with 2 pairs of bristles. Propleuron with 1 pale bristle on lower portion. Legs including coxae yellow with 5th tarsomeres brown (some specimens with black legs, except for yellow femoral base and tip). Hairs and bristles on legs pale yellow; coxa I with 2-4 anterior and apical bristles, coxa II with 3-4 anterior and apical bristles, coxa III with 1 brown outer bristle near middle. Femur II with 1 av and 1 pv apically, femur III with 1 av apically. Tibia II with 2 ad and 1 pd, apically with 3 bristles; tibia III with 2 ad, 2 pd, and row of pv, api- Abdomen metallic green with pale gray pollen, tergites and sternites brilliant. Hairs and bristles on tergites dark brown.
Female. Body length 1.5-1.7 mm, wing length 1.9-2.0 mm. Similar to male, with whole abdomen metallic green. Distribution. Known only from the type locality in Tibet.

Remarks.
This new species is similar to Chrysotimus ningxianus Wang, Yang & Grootaert, but may be separated from the latter by rounded first flagellomere, and the epandrium with 1 lateral epandrial process. In ningxianus, it has triangular first flagellomere, and the epandrium has 2 lateral epandrial processes (Wang et al. 2005).
Etymology. The specific epithet derives from the type locality in Tibet.
Head metallic green with gray pollen; frons and face brilliant; eyes separated distinctly. Hairs and bristles on head yellow. Ocellar tubercle weak, with 2 very long oc and 2 very short posterior hairs. Lower postocular bristles (including ventral hairs) pale. Antenna blackish; first flagellomere ( Fig. 14) rather short, about 0.4 times as long as wide; arista dorsal, with basal segment very short. Proboscis blackish, with brown hairs; palpus brown, with brown hairs and 2 brown apical bristles.
Distribution. Known only from the type locality in Tibet.
Remarks. This new species is similar to Chrysotimus guangdongensis Wang, Yang & Grootaert, but may be separated from the latter by the rowed d on tibia I, and the epandrium bearing no distinct lateral process. In guangdongensis, it lacks distinct rowed d on tibia I, and features a lateral process of the epandrium (Wang et al. 2005).
Etymology. The specific epithet derives from the collector of type species Xuankun Li. Head metallic green with gray pollen; frons and face brilliant; eyes separated distinctly. Hairs and bristles on head yellow. Ocellar tubercle weak, with 2 very long oc and 2 very short posterior hairs. Lower postocular bristles (including ventral hairs) pale. Antenna brown; first flagellomere subtriangular, about as long as wide; arista dorsal, with basal segment very short. Proboscis blackish, with brown hairs; palpus yellow, with yellow hairs and 2 brownish apical bristles.
Abdomen metallic green with pale gray pollen, tergites brilliant. Hairs and bristles on abdomen dorsal dark brown. Hypopygium (Fig. 16) metallic green (except pale hypandrium): Epandrium distinctly longer than wide, apically with 3 epandrial bristles and round short finger-like lateral epandrial process; long and curved surstylus with long bristles; cercus long with wide basal part, with long hairs and bristles; hypandrium short, pale.
Female. Body length 2.0 mm, Wing length 2.8 mm. Similar to male, with whole abdomen metallic green.
Distribution. Known only from the type locality in Tibet.
Remarks. This new species is similar to Chrysotimus ningxianus Wang, Yang & Grootaert, but may be separated from the latter by the black spot at tarsomere III1 base, and the epandrium with 1 single finger-like lateral epandrial process. In ningxianus, it has no black spot at tarsomere III1 base, and the epandrium has 2 lateral epandrial processes (Wang et al. 2005).
Etymology. The specific epithet derives from the collector of types Dr. Chaodong Zhu (Beijing).