Mysids associated with sea anemones from the tropical Atlantic: Descriptions of Ischiomysis new genus, and two new species in this Taxon (Mysida, Mysidae, Heteromysinae)

The males of Ischiomysis gen. nov. are unique among the currently known genera of the order Mysida by peculiar modifications of the ischium and praeischium of the eighth thoracic endopod. The type species, I. telmatactiphila sp. nov., forms compact aggregations above the oral disc of the club-tipped sea anemone Telmatactis cricoides from the island of São Tomé in the Gulf of Guinea. Less compact aggregations are formed by I. peterwirtzi sp. nov. from the island of São Vicente in the Cape Verde archipelago. Such looser aggregations were found in marine (micro)caves, wherein they extended over the anemones and adjacent rock recesses. An undetermined, visually similar mysid with similar distribution above the oral disc is documented by a colour photograph from Trindade, a small oceanic island in the tropical south-west Atlantic. Potential morphological relationships between the new genus and certain species of Heteromysis from the Caribbean and the Indian Ocean are discussed.