The first zoeal stages of the snapping shrimps Alpheus carlae and A. intrinsecus from Brazil were obtained from laboratory-hatched specimens and a detailed morphological description is provided. The morphological characteristics of both species are compared with available descriptions of other Alpheus species with a known first zoeal stage. Remarks from a semi-quantitative comparison of species belonging to A. armillatus species complex (A. carlae and A. brasileiro) and a comparison between larvae of A. intrinsecus from two localities in Brazil are presented. It was possible to distinguish first zoea of both species from the other congeners based on morphology. No intraspecific variability was detected between A. intrinsecus larvae obtained from two locations. Some structures showed differences between species of the A. armillatus complex. However, generalizations and conclusions based on larval morphology for taxonomic rearrangements at this point need to be made with caution and accuracy, since data of a sufficient number of species are not yet available for comparison.

We report the occurrence of the sponge-dwelling snapping shrimp Synalpheus dardeaui (Decapoda: Alpheidae) for the first time from Porto Seguro (Bahia, Brazil) and record an additional sponge host for the species, Ircinia cf. strobilina. Synalpheus dardeaui was previously known from Florida and some localities in the Caribbean Sea. Therefore, the present finding represents the first record of the species in the south-western Atlantic, extending its southern distribution limit by a latitude of 28° from Curaçao (12°N) to Porto Seguro (16°S). Variations between the Brazilian and Florida–Caribbean materials are discussed and illustrated.