Revealing a new eyeless Nereis (Nereididae: Annelida) clade from deep-sea organic falls

Abstract

Abstract Three new eyeless species of Nereis from organic falls (whale bones and wood parcels) in the Southwestern Atlantic from depths between 550 and 3285 m are described, and the eyeless species Neanthes shinkai is transferred to Nereis. All new species and Nereis shinkai comb. nov. can be distinguished from the majority of Nereis species by the absence of eyes and by the presence of small and delicate paragnaths. Interestingly, the species Nereis anoculepitoka sp. nov. presents epitoky, with sexual dimorphism and the morphological variations described herein. This is the first description of an eyeless epitoke form from organic falls in the deep ocean. We conducted molecular phylogenetic analyses using COI and 16S mitochondrial genes, confirmed the morphological identification and established an eyeless clade within Nereis including the three new species and Nereis shinkai comb. nov. The presence of different species in a relatively small geographical area can be explained, in part, by the action of different water masses in each sampling site and suggests that organic islands are potential hotspots for specialization of Nereis in the deep sea.