The taxonomy of two trichodactyline genera of the Neotropical freshwater crab family Trichodactylidae are revised. The genus Avotrichodactylus Pretzmann, 1968, includes two species, A. constrictus (Pearse, 1911) and A. oaxensis Rodríguez, 1992; the genus Rodriguezia Bott, 1969, also has two species, R. mensabak Cottarelli and Argano, 1977, and R. villalobosi (Rodríguez and Manrique, 1967). The taxonomic statuses of all the species are discussed and a short diagnosis is provided for each. A complete list of the material examined and a map of geographic distribution of the species are furnished.
Brachyura; Crustacea; Mexico; Neotropical region; Systematics