First zoeal stages of four Sesarma species from Panama, with identification keys and remarks on the American Sesarminae (Crustacea: Brachyura: Grapsidae)

was obtained from laboratory-hatched material in Panama. Zoeae I of the four Sesarma species are described and illustrated. Larvae of the other three species were used to complete or correct the chaetotaxy of the original descriptions. Larval features are compared among these species and with those of other American Sesarminae. In order to facilitate the study of plankton-collected material, two keys for identification of the known zoea I of sesarmine crabs from Panama are provided: one for Caribbean waters and the other for the Pacific coast. Remarks are given on the generic relation-ships within the American Sesarminae, the taxonomic position of the genera Cyclograpsus and Chas-magnathus, and the relevance of the reduction of larval stages