Key to the species of Triuncina in China

1. Socii pointed..............................................................................2

- Social rounded............................................................................. ..4

2. Uncus not bifid..............................................................................3

- Uncus bifid........................................................................... T. nitida

3. Saccus swollen apically............................................................... T. brunnea

- Saccus not swollen apically........................................................ T. diaphragma

4. Saccus longer, slender, slightly swollen apically, about 1/3 length of the whole male genitalia......... T. xiongi

- Saccus shorter, thick, constricted basally, about 1/5 length of the whole male genitalia................. T. daii