PETROLISTHES TRIDENTATUS: THE DEVELOPMENT OF LARVAE FROM A PACIFIC SPECIMEN IN LABORATORY CULTURE WITH A DISCUSSION OF LARVAL CHARACTERS IN THE GENUS (CRUSTACEA: DECAPODA; PORCELLANIDAE)

¹ School of Marine and Atmospheric Sciences, University of Miami, 10 Rickenbacker Causeway, Miami, Florida 33149

Petrolisthes tridentatus is a shallow water amphi-Panamanian porcellanid crab. The complete development from hatching through meglopal stage for larvae obtained from a Pacific specimen is described and illustrated. The larval development under laboratory conditions consists of a pre-zoeal stage lasting about two hours, followed by two zoeal stages lasting from three to six and five to 11 days, respectively. The megalopal stage lasts from seven to 17 days. Data from the larvae cultured at different temperatures indicate that P. tridentatus can complete its life cycle under laboratory conditions in as little as two weeks at 29° C, and usually in less than a month at 20° C.

The zoeal and megalopal stages of P. tridentatus exhibit several features, notably on the coxopodite of maxilliped 1, the last three abdominal somites, and the elongate plumose processes on the telson in the zoeal stages, and on the distal segments of the pereiopods in the megalopal stage which may allow these stages to be recognized in the plankton. P. tridentatus zoeae also exhibit telsonic features which clearly place the larvae in the Petrolisthes-group of larvae established by Lebour.

The zoeae of P. tridentatus have several features in common with other known Petrolisthes spp. larvae. These features are discussed and compared in an attempt to provisionally delineate larval characters at the generic level. These characters are differentiated from those known to occur in larvae of Pachycheles and Megalobrachium, the other members presently belonging to the Petrolisthes-group of larvae.