Gerris species

Polhemus, J. T., 2012, The water skater genus Gerris Fabricius (Hemiptera: Heteroptera: Gerridae) in Vietnam, with the description of a new species, Zootaxa 3382, pp. 20-28 : 21

Key to Gerris species of Vietnam

1. Pronotal lobe rufous. Sternum 7 of male with hind margin broadly concave, not medially emarginated. Endosoma: ventral sclerite separated and small. Sternum 7 of female with hind margin slightly produced medially................................................................................................. Gerris (Macrogerris) gracilicornis

- Pronotal lobe black. Hind margin of sternum 7 of male with median notch. Endosoma not as above. Sternum 7 of female with hind margin broadly concave............................................................................ 2

2. Larger species (length more than 10mm). Posterior mesosternum, metasternum, and abdominal venter with narrow medial, longitudinal ridge. Male with median notch of sternite 7 narrow. Female with connexival spines short, triangular........................................................................................ Gerris (s. str.) latiabdominis

- Smaller species (length less than 9mm). Mesosternum, metasternum, and abdominal venter without median ridge. Male: median notch of sternite 7 wide ( Fig. 5). Female with connexival spines long and slender........................... 3

3. Male: sterna 6 and 7 without median impression. Female: posterior margin of tergite 7 subequal to anterior margin; connexival spines pointed caudad, parallel in dorsal view.......................................... Gerris (s. str.) nepalensis

- Male: sterna 6 and 7 with distinct median impression. Female: posterior margin of tergite 7 distinctly narrower than anterior margin; connexival spines pointed dorsocaudad and curved inwards in dorsal view ( Fig. 14)..... Gerris (s. str.) curvus sp. n.