Sybistroma Meigen, 1824

Key to the species of Sybistroma Meigen View in CoL View at ENA from Sichuan and Yunnan (males)

This key builds extensively on Yang et al. ( 2011) but has scattered modifications based on material examined for the present study in ZIN collection, plus the inclusion of a new species.

1. Antenna with postpedicel rather short, as long as wide, obtuse apically ............................ 2

– Postpedicel elongated, distinctly longer than wide, acute apically .................................... 3

2. Postocular setae wholly black ( Yunnan) ................. S. compressa (Yang et Saigusa, 2001) View in CoL

– Middle and lower postocular setae yellow ( Sichuan, Yunnan) ....... S. acutata (Yang, 1996) View in CoL

3. Cercus nearly quadrate, with a big apical incision, or nearly triangular with obliquely concave outer margin ........................................................................................................ 4

– Cercus not as stated above .................................................................................................... 7

4. Hind femur with 1 long ventral bristle basally; cercus somewhat triangular, with obliquely incised outer margin ( Sichuan) ............................................... S. emeishana (Yang, 1998) View in CoL

– Hind femur without ventral bristles; cercus somewhat quadrate, with a big apical incision ... ............................................................................................................................................ 5

5. Middle and lower postocular setae pale; arista-like stylus with black swollen apex ( Henan, Shaanxi, Sichuan) ........................................................................... S. flava (Yang, 1996) View in CoL

– Postocular setae wholly black; arista-like stylus not swollen apically ................................. 6

6. Antenna with only basal ventral area of postpedicel dark yellow; postpedicel long ( Sichuan) ...................................................................... S. binigra (Yang et Saigusa, 1999) View in CoL

– Antenna with postpedicel wholly yellow; postpedicel short, triangular ( Sichuan) ............... .............................................................................. S. longaristata (Yang et Saigusa, 1999) View in CoL

7. Middle and lower postocular setae pale; lower calypter with yellow hairs ......................... 8

– Postocular setae wholly black; lower calipter with black hairs ............................................ 9

8. Postpedicel 2.4 times longer than wide; arista-like stylus with two dark swellings ( Gansu, Ningxia, Sichuan, Shanxi) ............................................................... S. incisa (Yang, 1999) View in CoL

– Postpedicel 2.9 times longer than wide; arista-like stylus with one black and white swelling ( Yunnan) .................................................................................................... S. genriki View in CoL sp. n.

9. Arista-like stylus subapical; antenna blackish with extreme base of postpedicel yellow ( Sichuan) .............................................................................. S. sichuanensis (Yang, 1998) View in CoL

– Arista-like stylus dorsal or subdorsal .................................................................................. 10

10. Thorax and abdomen partly yellow; postpedicel with additional arista-like process apically ( Henan, Shaanxi, Yunnan) ........................................... S. biaristata (Yang, 1999) View in CoL

– Thorax and abdomen metallic green (at most with metapleuron yellow); apex of postpedicel swollen, wholly black, without additional arista-like process ( Yunnan) ............................. ............................................................................................... S. yunnanensis (Yang, 1998) View in CoL