An integrative approach distinguishes three new species of Abyssochrysoidea (Mollusca: Caenogastropoda) associated with organic falls of the deep south-west Atlantic

Two new species of Rubyspira and one of Cordesia (Gastropoda: Abyssochrysoidea) are described morphologically and genetically, based on specimens collected from whale bones and wood parcels artificially implanted in the deep southwest Atlantic Ocean, at c. 1500 and 3300 m depths. Rubyspira pescaprae sp. nov. and R. elongata sp. nov. occur preferentially on whale bones. Cordesia atlantica sp. nov. is dominant on wood parcels. Distribution of Cordesia was hitherto only associated with hydrocarbon seeps off West Africa. Stable isotopes and gut content analyses were carried out to check possible trophic pathways. Both Rubyspira species are bone eaters, while Cordesia atlantica seems to rely on a wider range of food sources, including juveniles of wood-specialized xylophagid bivalves. Morphological and genetic evidence suggest that Rubyspira and Cordesia are more closely related to Abyssochrysos than to any other Abyssochrysoidea snails. In the present study, Cordesia is considered part of the family Abyssochrysidae based on molecular and morphological evidence, such as the presence of a penis and pallial tentacles arrangement. (AU)