A new Capitella polychaete worm (Annelida: Capitellidae) living inside whale bones in the abyssal South Atlantic

•A new Capitella species has been described for deep sea whale falls communities.•The new species is one of the most abundant polychaetes inhabiting the bones.•High genetic divergence between the new species and the other ones.•Occurrence of hermaphroditism due to the opportunistic life history of the group.•Population dynamics controlled by organic matter and high concentration of sulfide.

A new species of the genus Capitella, Capitella iatapiuna sp. nov., has been found in deep sea whale-fall samples, São Paulo Ridge-Southwest Atlantic. The new species is mainly characterized by a bluntly rounded prostomium and a very distinct peristomium forming a complete ring. Ribosomal 16S sequences were obtained and used for inter-specific comparisons. This species is herein described and compared to others species of the genus. Its ecological role in the whale-fall community is also discussed.