New species of bone-eating worm Osedax from the abyssal South Atlantic Ocean (Annelida, Siboglinidae)

Abstract

A new species of bone-eating annelid, Osedaxbraziliensis sp. n. , found in a sunken whale carcass at a depth of 4,204 m at the base of the São Paulo Ridge in the South Atlantic Ocean off the Brazilian coast is described. The organism was retrieved using the human-occupied vehicle Shinkai 6500 during the QUELLE 2013 expedition. This is the 26 th species of the genus and the first discovery from the South Atlantic Ocean, representing the deepest record of Osedax worldwide to date. This species morphologically resembles Osedaxfrankpressi but is distinguished by the presence of a yellow bump or patch behind the prostomium and its trunk length. Molecular phylogenetic analysis using three genetic markers ( COI , 16S , and 18S ) showed that O.braziliensis sp. n. is distinct from all other Osedax worms reported and is a sister species of O.frankpressi .