New decapod crustacean fossils collected from Eocene rocks of Algarrobo, Chile, have yielded a new genus and species of callianassid, Melipal chilensis. The large sample size makes it possible to recognize marked sexual dimorphism of the major cheliped and pronounced heterochely in the new taxon. Cretaceous fossils from Algarrobo are referred to Protocallianassa saetosa (Fo¨rster and Stinnesbeck, 1987) new combination. That genus is rather large and unwieldy as currently understood, but examination of type material will be necessary to revise it.