Key to males of extant species of Parasycorax Duckhouse (modified from Santos et al., 2009)

1. Gonostylus with multiple branches....................................................................... 2

- Gonostylus simple, without branches...................................................................... 3

2. Gonostylus bifurcate at base; outer branch with five spiniform bristles inserted apically, one elongate spiniform bristle inserted at base; mesal branch simple, elongate, sigmoidal in shape, darkly sclerotized (Fig. 7); Brazil ....... P. sigmoidalis sp. nov.

- Gonostylus bifurcate at base; outer branch with two spiniform bristles inserted apically; mesal branch bifurcate, darkly sclerotized (Santos et al., 2009; Fig. 15); Brazil ................................. P. bidentis Santos, Ferreira & Bravo, 2009

3. Gonostylus with two spiniform bristles inserted at apex; Philippines ........................ P. filipinae (Quate, 1965)

- Gonostylus set with three or more spiniform bristles......................................................... 4

4. Gonostylus set with three spiniform bristles; one inserted at apex, two on mesal surface (Santos et al., 2009; Fig. 6); Brazil ............................................................................... P. satchelli (Barretto, 1956)

- Gonostylus set with at least fifteen bristles of varying shape; Colombia ....... P. utriensis (Bejarano, Duque & Vélez, 2008)