Key to species of genus Symplanella (modified from Yang and Chen, 2014) (males)

1. Frons and clypeus mostly blackish or dark brown........................................................... 2

- Frons and clypeus mostly not blackish or dark brown........................................................ 5

2. Head in lateral view with the apex acute (Yang and Chen, 2014: fig. 16)................. S. hainanensis Yang and Chen

- Head in lateral view with the apex rounded................................................................ 3

3. Anal segment short (Figs 22–23)........................................................ S. nigricans sp. nov.

- Anal segment rather long............................................................................... 4

4. Frons and clypeus mostly blackish brown (Yang and Chen, 2014: fig. 29); pygofer with one stout process at middle (Yang and Chen, 2014: fig. 32)............................................................. S. zhongtua Yang and Chen

- Frons and clypeus mostly dark brown (Chen et al., 2014: fig. 2–101, E); pygofer with one lobe-like process at dorsal posterior angle (Chen et al., 2014: figure 2–101, I)................................. S. brevicephala (Chou, Yuan and Wang)

5. Body mainly reddish yellow (Figs 1–2)....................................................... S. fulva sp. nov.

- Body mainly not reddish yellow......................................................................... 6

6. Median of forewing with three branches (Fennah, 1987: fig. 6); genital style long in posterior view, posterior margin broadly concave (Fennah, 1987: fig. 5)........................................................... S. breviceps Fennah

- Median of forewing with four branches; genital style short in posterior view, posterior margin not concave or slightly convex ................................................................................................... 7

7. Posterior margin of pygofer with one process (Zhang and Wang, 2009: fig. 6)............ S. unipuncta Zhang and Wang

- Posterior margin of pygofer without process (Yang and Chen, 2014: fig. 9)................. S. recurvata Yang and Chen