Abbreviated development of Armases miersii (Grapsidae : Sesarminae), a crab that breeds in supralittoral rock pools

Armases miersii is the only crab known to complete larval development in su pralittoral rock pools. This habitat is characterized by harsh and highly v ariable abiotic and biotic conditions, requiring ecophysiological and ontog enetic adaptations. In this study, the complete larval development of Armas es miersii from laboratory-cultured and field-collected material from Jamai ca is described. Development consists of 3 zoeal stages followed by a megal opal stage. It is thus abbreviated in comparison to other species of the ge nus Armases and the closely related Aratus pisonii, which have 4 zoeae and 1 megalopa. Morphology of the zoeal and megalopal stages is compared with t hose of other species of the genera Armases and Aratus for which larval dev elopment has been described. The reduction of zoeal stages is discussed in relation to its ecological and evolutionary relevance.