A new genus and species of large mussel (Mollusca: Bivalvia: Mytilidae) from the Kermadec Ridge: Tuhinga 21

Tuhinga 21: 59 - 73

ABSTRACT: A large mussel, Vulcanidas insolatus new genus and new species, is described from active venting sites on Macauley and Giggenbach submarine volcanoes off Macauley Island, Kermadec Islands, northeast of New Zealand’s North Island. Based on morphology, the phylogenetically basal position of the new species to other large mussels from hot vents and cold seeps is confirmed: Vulcanidas n.gen. is closer to small mussels associated with sunken wood and whale falls (Modiolinae, genera Idas Jeffreys, 1876, Adipicola Dautzenberg, 1927 and Benthomodiolus Dell, 1987). The new mussel has enlarged gills that support endosymbiotic sulphur-oxidising bacteria, a longer digestive tract than in other mussels from vents and seeps, and, uniquely, dendritically textured gonadal tissue on the inner mantle lobes. Vulcanidas insolatus lives in dense beds as shallow as 140 m, and is the shallowest-living vent or seep mussel.

KEYWORKDS: Mollusca, Bivalvia, Mytilidae, Modiolinae, Bathymodiolinae, mussel, Vulcanidas insolatus, new genus, new species, hot vent, chemoautotrophic bacteria, New Zealand, Kermadec Ridge, submarine volcano.