Morphology of the megalopa and first crab stage of the mediolittoral crab Pachygrapsus marmoratus (Brachyura, Grapsidae, Grapsinae)

Megalopae of the grapsid crab Pachygrapsus marmoratus were captured from a mediolittoral rocky shore in the western Mediterranean and juveniles were obtained by rearing the megalopae in the laboratory. The megalopa and the first crab stage are described and illustrated. The morphological characters of the megalopa of P. marmoratus are compared with those of the other known megalopae of the subfamily Grapsinae.