Discovery and description of a remarkable bathypelagic nudibranch, Bathydevius caudactylus, gen. et. sp. nov.

Abstract

We describe an exceptional nudibranch, new to science, from bathypelagic depths in the eastern North Pacific Ocean. More than 100 individuals of Bathydevius caudactylus gen. et. sp. nov. have been observed in the water column at depths between 1013 and 3272 m. Twenty spawning individuals were observed on the seafloor at depths between 2269 and 4009 m. Anatomy, diet, behavior, bioluminescence, and habitat distinguish this surprising nudibranch from all previously described species, and genetic evidence supports its placement in a new family.