A new genus and new species of the family Callistoplacidae from the bathyal zone near Guadeloupe Island in the Caribbean Sea are described. Caribbochiton guadeloupensis n. gen. et n. sp. is unlike other genera in the family Callistoplacidae: it has no ribs on end valves or on lateral areas of intermediate valves. According to other morphological features (thick shell, relatively narrow valves, noticeably raised lateral areas, similar slit formula, insertion plate teeth thickened at edges of slits, dorsal scales), this genus is closest to the family Callistoplacidae. Given that a number of species of the family do not have at a young age the ribs which appear later, we hypothesise that the new genus could have evolved as a result of paedomorphosis. An emended diagnosis of the family Callistoplacidae is hereby proposed. |
