Key to species of Sisyrina

1. Antenna with several basal segments (seven or eight) darker than remaining ones.................................. 2

- Antenna with only scape and pedicel darker than flagellum.................................................... 4

2. Male gonocoxite 9 broad basally, rod-shaped distally and curved ventrad (Fig. 8)............. S. qiong Yang & Gao, 2002

- Male gonocoxite 9 long and elliptical......................................................................3

3. Antenna with basal eight segments black and remaining flagellomeres yellow; male gonocoxite 9 with a slender ventral spine distally and dorsal margin sinuous; female tergum 9 nearly 1.5 times as long as wide (Smithers 1973: Figs. 1, 3)......................................................................................... S. tropica Smithers, 1973

- Antenna with basal seven segments dark brown and remaining flagellomeres pale yellow; male gonocoxite 9 with a thick distal ventral spine and dorsal margin rounded; female tergum 9 nearly twice as long as wide (Monserrat 1981: Figs. 21–22; Smithers 1973: Figs. 2, 4).................................................................... S. nirvana Banks, 1939

4. Female tergum 9 with dorsal margin nearly as long as posterodorsal margin; gonocoxite 9 slightly curved distally, nearly four times as long as wide (Fig. 4D–E)......................................................... S. fashengi sp. nov.

- Female tergum 9 with dorsal margin nearly twice as long as posterodorsal margin; gonocoxite 9 abruptly curved distally into a hook-like apex, nearly three times as long as wide (Fig. 5D–E)................................ S. vietnamica sp. nov.