A new genus and five new species of mussels (Bivalvia, Mytilidae) from deep-sea sulfide/hydrocarbon seeps in the Gulf of Mexico

Five new species of modioliform mussels in the family Mytilidae are describ ed from material collected at sulfide/hydrocarbon seeps in the Gulf of Mexi co. New definitive taxa, placed in the subfamily Bathymodiolinae, include t he genus Tamu and the species Tamu fisheri from hydrocarbon seeps on the Lo uisiana Continental Slope, Bathymodiolus heckerae from brine seeps at the b ase of the West Florida Escarpment in the eastern Gulf of Mexico, and Bathy modiolus brooksi from the West Florida Escarpment site and from hydrocarbon seeps at Alami (n) over tilde os Canyon in the western Gulf of Mexico. An additional two new mussel species, which exhibit combinations of morphologi cal characters unlike any existing mytilid genus but for which molecular da ta are equivocal, are provisionally placed in the genera Bathymodiolus and Idas, respectively. These are: "Bathymodiolus" childressi from hydrocarbon seeps at Alami (n) over tilde os Canyon and the Louisiana Continental Slope , and "Idas" macdonaldi (in the subfamily Modiolinae) from hydrocarbon seep s on the Louisiana Continental Slope.