HETEROMYSIS SABELLIPHILA SP NOV (MYSIDA, MYSIDAE, HETEROMYSINAE) IN FACULTATIVE ASSOCIATION WITH SABELLIDS FROM THE CAPE VERDE ISLANDS (SUBTROPICAL NE ATLANTIC)

A survey of crustaceans associated with benthic invertebrates in near-shore habitats at islands of the Cape Verde archipelago yielded a new species belonging to the genus Heteromysis, subgenus Olivemysis: H. sabelliphila sp. nov. shows a non-obligatory association with the sabellid polychaete Branchiomma nigromaculatum only during the night. This is the first documented mysid-polychaete association. The mysids apparently took particles collected by the polychaete, suggesting a kleptoparasitic interspecific relationship. A set of three specifically modified setae on the antennular trunk is shared by the new species with two Heteromysis species from Madeira (subtropical N. E. Atlantic), suggesting a close morphological relationship within the subgenus Olivemysis: with H. wirtzi, commensal of the sea anemone Telmatactis cricoides, and with H. dardani, commensal of the hermit crab Dardanus calidus. A key to the Heteromysinae of the E. Atlantic and Mediterranean is given.