The megalopa stage of the hydrothermal vent crab genus Bythograea (Crustacea, Decapoda, Bythograeidae)

The megalopa larva stage of the hydrothermal vent crab genus Bythograea Williams, 1980, is described and illustrated based on larval stages attributed to B. thermydron Williams, 1980, from vents on the East Pacific Rise. The megalopa of Bythograea is a large and generalized developmental stage, with virtually no obvious morphological adaptations that would indicate either an unusual habitat or clues as to the phylogenetic placement of bythograeid crabs within the Brachyura. Aspects of larval development and natural history of the megalopa and postlarval stages of vent crabs are summarized.