Apherusa delicata n. sp., a new suprabenthic amphipod (Crustacea, Eusiroidea, Calliopiidae) from the northern Bay of Biscay, with a discussion of the genus

A new calliopiid amphipod, Apherusa delicata n. sp., is described from specimens sampled with a suprabenthic sled in the ‘Grande Vasière’ area (northern Bay of Biscay). The new species can be distinguished from its sympatric congeners, A. bispinosa and A. ovalipes, mainly by the posterodorsal tridentate armature of pleosomites 2 and 3 and by the smooth posterior margin of epimeral plate 3. Its geographical distribution seems to be restricted to muddy sand bottoms of the ‘Grande Vasière’ fishing grounds. A key to the 20 known species of Apherusa is provided, followed by a discussion on the morphological characters to be considered for a future cladistic analysis of species within this genus.