Key to Stenus species of Zhuji City

1 Legs with tarsomeres IV distinctly simple.................................................................. 2

- Legs with tarsomeres IV distinctly bilobed................................................................. 11

2 Abdominal segments without paratergites....................................................... S. pilosiventris

- Abdominal segments with distinct paratergites............................................................... 3

3 Elytra each with an orange spot.................................................................. S. tenuipes

- Elytra entirely black................................................................................... 4

4 Abdominal tergites of segments III–V without longitudinal basal carina........................................... 5

- Abdominal tergites of segments III–V with longitudinal basal carinae............................................ 6

5 Basal half of femora distinctly lighter than apical half (applicable only on the population from Tianmushan Area), male sternite VII with posteromedian portion flattened, internal sac of aedeagus broad................................... S. eurous

- Basal half of femora slightly lighter than apical half, male sternite VII with posteromedian portion distinctly impressed, inter- nal sac of aedeagus narrow.................................................................... S. pubiformis

6 Abdominal tergites of segments III–V with three longitudinal basal carinae........................................ 8

- Abdominal tergites of segments III–V with four longitudinal basal carinae.................... S. melanarius melanarius