FIRST ZOEAL STAGES OF 4 SESARMA SPECIES FROM PANAMA, WITH IDENTIFICATION KEYS AND REMARKS ON THE AMERICAN SESARMINAE (CRUSTACEA, BRACHYURA,GRAPSIDAE)

The first zoeal stage of the grapsid crabs Sesarma aequatoriale Ortman n, 1894, S. rubinofforum Abele. 1973, S.rhizophorae Rathbun, 1906, S.c uracaoense de Man, 1892, Armases ricordi (H. Milne Edwards, 1853), A.r ubripes (Rathbun, 1897) and Cyclograpsus integer H. Milne Edwards, 183 7 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 s pecies and with those of other American Sesarminae. In order to facili tate the study of plankton-collected material, two keys for identifica tion 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 relationships within the American Sesarminae, the taxonomic position of the genera Cyclograpsus and Chasmagnathus, and the relevance of the reduction of larval stages.