The First Zoeal Stage of Johngarthia Lagostoma (H. Milne Edwards, 1837) (crustacea: Brachyura: Gecarcinidae), with Comments on the Validity of the Genus

The land crab Johngarthia lagostoma is endemic to the Atlantic oceanic islands of Ascencion, Trindade and Martin Vaz, Fernando de Noronha and the Rocas Atoll. A previous study found significant genetic structure in J. lagostoma between the oceanic islands of Trindade and Fernando de Noronha/Rocas Atoll. Likewise, the first stage zoea, herein described and illustrated based on material from the remote oceanic of Trindade, is reported differ morphologically in minor details from J. lagostoma zoea I previously described from Fernando de Noronha and Rocas Atoll. Johngarthia lagostoma and J. planata from the eastern tropical Pacific are shown to differ in the setation of the antenna and coxae of the maxillule and maxilla. No characters from the first zoeal stage and from the adult morphology can be set forth as diagnostic for Johngarthia. The uncommon large eye of the first zoea of J. lagostoma is here suggested as an autapomorphy to J. lagostoma but future research may reveal that this character is actually more widely distributed within the genus Johngarthia.