Among the portunid crabs collected during the Ilha Grande Project (1966-1969), one specimen of Polybius navigator (Herbst, 1794) was found. This species formerly known from the Eastern Atlantic, Mediterranean and Adriatic and Black Seas is redescribed, illustrated and comments on the new status of the genus is done. It is the first record of this species for the Brazilian coast and Western Atlantic.
Portunidae; Polybius navigator; Brazilian coast; Western Atlantic; first record