Research Article |
Corresponding author: Ding Yang ( dyangcau@126.com ) Academic editor: Marija Ivković
© 2015 Ning Wang, Baohai Wang, Ding Yang.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Wang N, Wang B, Yang D (2015) Two new species of the genus Diostracus Loew from Tibet, with a key to the Himalayan fauna (Diptera, Dolichopodidae). ZooKeys 488: 91-104. https://doi.org/10.3897/zookeys.488.8919
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Previously only one species of the genus Diostracus was known to occur in Tibet. Here the following two new species are added to the fauna of Tibet: Diostracus acutatus sp. n. and D. tibetensis sp. n. Their relationships with similar species are discussed. A key to the species of Diostracus from the Himalayas is presented.
Diptera , Dolichopodidae , Diostracus , new species, Tibet
The genus Diostracus is a large genus in the subfamily Hydrophorinae and includes dolichopodids living on wet rocks and stones in mountain streams (
Only one species, Diostracus nebulosus Takagi, of the genus Diostracus was known to occur in Tibet (
Type specimens are deposited in the Entomological Museum of China Agricultural University (CAU), Beijing. Morphological terminology generally follows
(modified from
1 | Only posterior npl present, anterior npl absent (unisetosus-group) | 2 |
– | Anterior and posterior npl present | 4 |
2 | Discal cell with 1-2 accessory cellulae at anterodistal corner ( |
3 |
– | Discal cell without accessory cellulae at anterodistal corner ( |
Diostracus unisetosus Saigusa |
3 | 6 dc; mid femur without spine-like av | Diostracus nigrilineatus Saigusa |
– | 5 dc; mid femur with 3-5 spine-like av at basal 1/4 | Diostracus bisinuatus Saigusa |
4 | Empodium and pulvilli reduced into minute protuberance (fenestratus-group) | 5 |
– | At least empodium well developed, hair-like and ventrally ciliated | 14 |
5 | ph near transverse suture; vt absent (fenestratus-subgroup) | 6 |
– | ph near h; vt present | 8 |
6 | Mid and hind femora without long hairs and bristles; mid tibia long ciliated | 7 |
– | Mid femur with thick clump of erect golden yellow pv hairs between basal 1/3 and 1/2, hind femur with row of erect av except basal and apical 1/4; mid tibia simple | Diostracus ramulosus Takagi |
7 | Jet-black nodule of discal crossvein about 5 times as long as wide; 5 accessory cellulae formed at anterodistal corner of discal cell; cercus uniformly short yellow haired | Diostracus reticulatus Saigusa |
– | Jet-black nodule of discal crossvein about 2.6 times as long as wide; 3 accessory cellulae formed at anterodistal corner of discal cell; cercus with long golden hairs apically | Diostracus fenestratus Saigusa |
8 | Discal crossvein strongly sinuate, S-shaped; anterodistal corner of discal cell with an accessory cellula (pulchripennis-subgroup) | 9 |
– | Discal crossvein nearly straight; anterodistal corner of discal cell without accessory cellula (flex-subgroup) | 11 |
9 | Lateral portion of abdominal tergite 5 projected into an elongate process; mid tibia without row of erect fine posterior bristles | 10 |
– | Lateral portion of abdominal tergite 5 expanded into a broad triangular lobe; mid tibia with row of erect fine posterior bristles | Diostracus pretiosus Saigusa |
10 | Mid femur ventrally weakly raised subbasally, with modified hairs and bristles | Diostracus emotoi Saigusa |
– | Mid femur evenly flattened ventrally throughout and nearly bare | Diostracus pulchripennis Saigusa |
11 | Wing shape normal, without finger-like lobe at posterior margin | 12 |
– | Wing shape anomalous, with a finger-like lobe at posterior margin ( |
Diostracus pennilobatus Saigusa |
12 | Fore tarsomere 1 with an obtuse apicoventral corner, fore tarsomere 2 without finger-like process near extreme base ( |
13 |
– | Fore tarsomere 1 with a nearly acute apicoventral process, fore tarsomere 2 with a short finger-like ventral process near extreme base (figs 2, 5) | Diostracus acutatus sp. n. |
13 | Fore tarsomere 1 with apicoventral corner rounded ( |
Diostracus flexus Saigusa |
– | Fore tarsomere 1 with apicoventral corner angulated ( |
Diostracus nishidai Saigusa |
14 | Pulvilli atrophied, bare (impulvillatus-group) | 15 |
– | Pulvilli well developed, pad-like, pilose | 19 |
15 | Fore tarsomere 1 not furcate apically, fore tarsomere 2 shorter than tarsomere 1 ( |
16 |
– | Fore tarsomere 1 furcate apically, fore tarsomere 2 much longer than tasomere 1 ( |
Diostracus angustipalpis Saigusa |
16 | Wing without dark spot at discal crossvein; fore tarsomere 1 swollen apically ( |
17 |
– | Wing with a circular grayish spot at discal crossvein; fore tarsomere 1 not swollen apically ( |
Diostracus longiunguis Saigusa |
17 | Fore tarsomere 1 weakly dilated apically, 1.5 times thicker than its base ( |
18 |
– | Fore tarsomere 1 strongly dilated apically, 3 times thicker than its base ( |
Diostracus chaetodactylus Saigusa |
18 | Cercus 3 times as long as wide, parallel-sided ( |
Diostracus impulvillatus Saigusa |
– | Cercus about 1.5 times as long as wide, rather wide with narrow base ( |
Diostracus fulvispinatus Saigusa |
19 | Only 4 dc (quadrisetosus-group) | 20 |
– | 5–6 dc | 28 |
20 | Leg mostly yellowish | 21 |
– | Legs darkened, at most trochanters and knees tinged yellow | 23 |
21 | vt absent; fore tarsomere 1 without short erect av ( |
22 |
– | vt present; fore tarsomere 1 with row of short erect av ( |
Diostracus parvus Saigusa |
22 | Anterior npl absent | Diostracus janssonorum Saigusa |
– | Anterior npl present | Diostracus simplicipes Saigusa |
23 | Fore coxa subapically raised at anterior surface | 24 |
– | Fore coxa normal | 25 |
24 | Fore femur not strongly swollen basally ( |
Diostracus auripalpis Saigusa |
– | Fore femur strongly swollen basally ( |
Diostracus femoratus Saigusa |
25 | Face without grayish median stripe | 26 |
– | Face with a narrow grayish median stripe | Diostracus makiharai Saigusa |
26 | R4+5 distinctly thicker than R2+3; palpus at most 0.9 times as long as eye height | 27 |
– | R4+5 thinner than R2+3; palpus 1.1–1.2 times as long as eye height | Diostracus magnipalpis Saigusa |
27 | Palpus enlarged, about 3/4 as long as eye height ( |
Diostracus aurifer Saigusa |
– | Palpus not enlarged, about 1/3 as long as eye height | Diostracus quadrisetosus Saigusa |
28 | Lower postocular bristles including posteroventral hairs on head yellow | 29 |
– | Hairs and bristles on head wholly black (nigripilosus-group) | Diostracus nigripilosus Saigusa |
29 | First flagellomere triangular; arista subbasal | 30 |
– | First flagellomere not triangular; arista apical, subapical or dorsal | 31 |
30 | vt much shorter and thinner than pvt; wing broadly darkened along veins; fore tarsomere 1 slender ( |
Diostracus umbrinervis Saigusa |
– | vt almost as strong as pvt; wing not broadly darkened along veins; fore tarsomere 1 distinctly thickened apically ( |
Diostracus tangalensis Saigusa |
31 | Discal crossvein straight, without jet-black nodule or stripe (nebulosus-group) | 32 |
– | Discal crossvein bent, with a jet-black nodule or stripe | 33 |
32 | Mid and hind femora without ventral bristles; cercus long finger-like in lateral view ( |
Diostracus burmanicus Saigusa |
– | Mid and hind femora with ventral bristles; cercus short, subtriangular in lateral view ( |
Diostracus nebulosus Takagi |
33 | 5 dc | 34 |
– | At least 6 dc (unipunctatus-group) | 35 |
34 | M without dark cloud, discal crossvein with narrow jet-black nodule ( |
Diostracus alticola Saigusa |
– | M with a dark cloud, discal crossvein with rounded jet-black nodule ( |
Diostracus shimai Saigusa |
35 | First flagellomere short circular, nearly as long as wide ( |
36 |
– | First flagellomere distinctly or strongly elongated, distinctly longer than wide ( |
37 |
36 | Mid femur without very long yellow ventral bristles at base; first flagellomere with somewhat tapering apex ( |
Diostracus unipunctatus Saigusa |
– | Mid femur with several very long yellow ventral bristles at base ( |
Diostracus rotundicornis Saigusa |
37 | First flagellomere 1 apically strongly narrowed, not trapezoid | 38 |
– | First flagellomere 1 nearly trapezoid | 39 |
38 | Arista nearly apical ( |
Diostracus nepalensis Saigusa |
– | Arista subapical ( |
Diostracus gymnoscutellatus Saigusa |
39 | First flagellomere much elongated, about 2 times longer than wide ( |
40 |
– | First flagellomere 1.3–1.5 times longer than wide ( |
41 |
40 | Arista located at dorsoapical corner of first flagellomere ( |
Diostracus auripilosus Saigusa |
– | Arista dorsal ( |
Diostracus longicornis Saigusa |
41 | Arista subapical (Fig. |
42 |
– | Arista dorsal; vt extremely reduced, as long as diameter of lateral ocellus | Diostracus malaisei Saigusa |
42 | vt as strong as pvt; first flagellomere 1.5 times longer than wide ( |
Diostracus parvipunctatus Saigusa |
– | vt shorter and weaker than pvt; first flagellomere 1.3 times longer than wide (Fig. |
Diostracus tibetensis sp. n. |
vt rather short, 0.5 times as long as oc. First flagellomere somewhat triangular, 1.5 times longer than wide; arista apical (Fig.
Male. Body length 8.0 mm; wing length 8.5 mm.
Head metallic green with pale gray pollen. Eyes widely separated; face widened towards clypeus. Hairs and bristles on head black; lower postocular bristles including posteroventral hairs pale, mostly very long. Ocellar tubercle distinct, with pair of long strong oc, without posterior hairs; vt rather short, 0.5 times as long as oc, nearly as long as pvt. Antenna (Fig.
Thorax metallic green with pale gray pollen; mesoscutum with two pairs of dark brown longitudinal spots (middle pair strip-like). Hairs and bristles on thorax black; 6 mostly hair-like dc except posteriormost 1 dc longest and thick; acr absent; 1 h and 1 very short hair, 1 ph, 2 npl, 1 sa, 1 psa; scutellum with pair of long sc. Propleuron with short pale hairs on upper portion and long pale hairs on lower portion. Legs nearly entirely black except fore trochanter dark yellow; claws well developed, empodium and pulvilli reduced. Fore trochanter elongated, with hook-like posterior process (Fig.
Abdomen distinctly longer than head and thorax combined, metallic green with pale gray pollen. Abdomen with pale pubescence. Tergite 5 with lateral portion slightly extended downward. Sternite 1 with a nearly acute process at middle; sternite 4 medially with an obtuse anterior process and 2 short thin, contiguous posterior processes bearing bundle of brown hairs. Hypandrium not distinctly swollen.
Male genitalia (Fig.
Female. Unknown.
Holotype: male, China: Tibet, Nyingchi (N29°38'18", E94°21'46"), Sejilashan Mountain, Zhongshan Station, 4200 m, 20.VI.–10.VII. 2014, Malaise trap, leg. Baohai Wang and Zhaohui Pan (CAU).
China (Tibet).
The new species belongs to the flexus-subgroup of the fenestratus-group. It may be separated from D. flexus Takagi and D. nishidai Saigusa from Nepal by the fore tarsomere 1 with a nearly acute apicoventral process and fore tarsomere 2 with a short finger-like ventral process near the extreme base (Figs
The specific name refers to the fore tarsomere 1 with a nearly acute apicoventral process.
First flagellomere (
China (Tibet), Nepal.
This species belongs to the nebulosus-group.
vt rather short and weak, 0.4 times as long as oc. First flagellomere somewhat quadrate, 1.3 times longer than wide; arista subapical (Fig.
Male. Body length 6.4 mm; wing length 7.6 mm.
Head metallic green with pale gray pollen. Eyes widely separated; face widened towards clypeus. Hairs and bristles on head black; lower postocular bristles including posteroventral hairs pale, mostly very long. Ocellar tubercle distinct, with pair of strong oc, without posterior hairs; vt rather short and weak, 0.4 times as long as oc, 0.7 times as long as pvt. Antenna (Fig.
Thorax metallic green with pale gray pollen; mesoscutum with two pairs of dark brown longitudinal spots (middle pair strip-like). Hairs and bristles on thorax black; 6 slightly long dc, posteriormost dc longest; acr bristles absent; 1 h and 1 short bristle, 1 ph, 2 npl, 1 sa, 1 psa; scutellum with pair of long sc and 4 very short marginal hairs (2 hairs between 2 sc). Propleuron with short pale hairs on upper portion and mostly long pale hairs on lower portion. Legs entirely black; claws well developed, empodium and pulvilli distinct. Hairs and bristles on legs black except those on coxae pale; fore coxa with bundle of short dense black anterior hairs bristle-like at extreme tip; hind coxa apically with 4 long blackish anterior hairs bristle-like. Mid and hind femora with some pale ventral hairs. Fore femur with two rows of black ventral bristles (longest ones slightly shorter than femur thickness), and with 3 long posterior bristles at extreme base. Mid femur basally with nearly two close rows of long pale ventral hairs (longest ones about 3 times as long as femur thickness), subbasally with 4 black short thick av. Hind femur with about two close rows of long pale ventral hairs (longest ones about 3 times as long as femur thickness) and with 5 black short thick av. Fore tibia with 4 ad and 4 pv on apical half; apically with 3 bristles. Mid tibia with 3 ad and 2 pd; apically with 3 bristles. Hind tibia with 4 ad, 5 pd, 3 av and 6 pv; apically with 3 bristles. Fore tarsomere 1 with row of short dense erect av spines and one row of dense thin pv (longer than av). Relative lengths of tibia and five tarsomeres: LI 3.3: 1.6: 1.6: 0.8: 0.55: 0.7; LII 5.8: 2.9: 1.1: 0.75: 0.5: 0.75; LIII 7.1: 3.2: 1.9: 1.2: 0.6: 0.8. Wing (Fig.
Abdomen rather short, nearly as long as head and thorax combined, metallic green with pale gray pollen. Abdomen with pale pubescence except dorsum with some black hairs at middle. Tergites 4 distinctly and tergite 5 weakly with lateral portion extended downward; lateral portion of tergite 4 with very long hairs apically bent, slightly shorter than those on sternite 3, but lateral portion of tergite 5 only with short hairs.
Male genitalia (Fig.
Female. Unknown.
Holotype: male, China: Tibet, Nyingchi (N29°38'18", E94°21'46"), Sejilashan Mountain, Zhongshan Station, 4200 m, 20.VI.-10.VII. 2014, Malaise trap, leg. Baohai Wang and Zhaohui Pan (CAU).
China (Tibet).
The new species belongs to the unipunctatus-group. It is somewhat similar to D. parvipunctatus Saigusa from Nepal in the shape of the first flagellomere and fore and mid femora with long ventral hairs, but may be separated from the latter in the following points: vt is shorter and weaker than pvt; the first flagellomere is shorter, 1.3 times longer than wide, and the abdominal tergite 5 has the short lateral hairs. In D. parvipunctatus, vt is as strong as pvt or stronger; the first flagellomere is 1.5 times longer than wide (
The specific name refers to the type locality Tibet.
We are very grateful to Dr. Zhaohui Pan (Nyingchi) for collecting specimens and to Ms. Chufei Tang (Beijing) for her help during the study. Two anonymous reviewers are thanked for providing useful comments on an earlier draft of this paper. The research was funded by the National Natural Science Foundation of China (41301049, 31272354), a special fund for basic scientific research project in the central scientific research institutes (Institute of Grassland Research of CAAS) (1610332014012), and the Ministry of Science and Technology of the Republic of China (2014FY210200).