Eotrechinae

Nakthong, La-Au, Vitheepradit, Akekawat & Sites, Robert W., 2014, Key to the species of Eotrechinae (Hemiptera: Heteroptera: Gerridae) of Thailand and review of the fauna of the Phetchabun Mountain Range, Zootaxa 3860 (1), pp. 47-63 : 49

Subfamily Eotrechinae

Members of this subfamily are characterized by a body length of 3–11 mm, first antennal segment with preapical spine-like hairs, pronotal lobe of apterous form reduced, and claws inserted apically or close to apex ( Chen et al. 2005). In Thailand, Amemboa generally is found at the margins of streams, muddy tire ruts, and rock pools, whereas Onychotrechus and Eotrechus are generally found on vertical rock faces of waterfalls ( Vitheepradit 2008). Further, Onychotrechus is found close to water on vertical rock faces, whereas Eotrechus tends to occur in drier areas of the rock faces. During the dry season in northern Thailand, Onychotrechus esakii Andersen was found on emergent rocks and rocks at the margin of streams with the waterfalls almost completely dry (AV pers. obs).

Key to the genera of Eotrechinae of Thailand (modified from Polhemus & Andersen 1984)

1. Hind leg distinctly shorter than middle leg ( Fig. 3 ).................................................... Amemboa

1’. Hind leg subequal to or longer than middle leg ( Figs. 4, 5 )..................................................... 2

2. Claw inserted at apex of tarsus ( Fig. 6 ), body length 7.5–11.0 mm........................................ Eotrechus

2’. Claw inserted before apex of tarsus ( Fig. 7 ), body length less than 7.4 mm........................ Onychotrechus esakii

Figures

FIGURES 3 – 5. Genera of male Eotrechinae. (3) Amemboa, (4) Eotrechus, (5) Onychotrechus.

FIGURES 6 – 7. Distal leg segments showing pretarsal claws. (6) Eotrechus, (7) Onychotrechus.