Key to genera and species of Corixidae from Pará

(adapted from Hungerford 1948; Nieser 1970)

1a. Head, in lateral view, with posterior margin of eye almost straight; hypo-ocular suture arising near midway along posterior margin of eye (Fig. 9A); apices of clavi not exceeding a line drawn through nodal furrows of hemelytra in females and slightly exceeding in males (Fig. 9B); male protibia strongly produced apically over pala (Fig. 9C); male abdomen without prestrigil, with sinistral asymmetry and strigil on the left side (Fig. 9D)................... Trichocorixa orinocoensis Sailer, 1948

1b. Head, in lateral view, with posterior margin of eye concave; hypo-ocular suture arising from posteroventral angle of eye (Fig. 10A); apices of clavi distinctly exceeding a line drawn through nodal furrows of hemelytra in both sexes (10B); male protibia not produced over pala (Fig. 11A, 12A); male abdomen with prestrigil on dorsal segment V, with dextral asymmetry and strigil on the right side (Fig. 11B, 12B, 13A) (Heterocorixa White, 1879).............................................. 2

2a (1b). Mesopretarsal claw at most as long as respective tarsus; hemelytra lacking short spines on corium; metaxyphus as long as or longer than inner line of metacoxae (Fig. 10C); metafemur with little more than basal end pilose, with no more than 10–12 spines on ventral side; male with long prestrigilar comb and median lobe of tergum VII rounded (Figs. 11B, 12B)........ 3

2b. Mesopretarsal claw longer than respective tarsus; hemelytra with both slender setae and short spines on corium, hemelytral pattern very fine; metaxyphus with half the length of inner line of metacoxae (Fig. 13B); metafemur pilose on basal two-fifths, with many spines on ventral side; male with short prestrigilar comb and median lobe of the tergum VII triangular (Fig. 13A)................................................................ Heterocorixa hesperia hesperia (White, 1879)

3a (2a). Posterolateral margin of head slightly sinuate; male protibia with a long flap resting in a depression of the pala (Fig. 11A); posterior pruinose area of the embolar groove a little longer than that of claval suture; left paramere not strongly hooked apically (Fig. 11C)................................................... Heterocorixa boliviensis Hungerford, 1928

3b. Posterolateral margin of head slightly convex, not sinuate; male protibia without a flap as described above but with a carina on caudal side (Fig. 12A); posterior pruinose area of embolar groove considerably longer than that of claval suture; left paramere strongly hooked apically (Fig. 12C)................................... Heterocorixa chapadiensis Hungerford, 1928