First record of the genus Eliberidens (Annelida: Dorvilleidae) from the Southwestern Atlantic Ocean and cladistic analysis of the genus

Knowledge on the family Dorvilleidae Chamberlin, 1919 is still limited, mainly due to the scarcity of studies and the rarity of many genera and species in samples collected from shallow waters to great depths. This work presents a two folds aim: i) report the first record of Eliberidens from the Southwestern Atlantic Ocean, with Eliberidens forceps Wolf, 1986 and Eliberidens hartmannschroederae Hilbig, 1995; ii) providing a morphological cladistic analysis to test the monophyly of Eliberidens and its relationship with related genera. These new records increase the taxonomic knowledge and distribution of dorvilleids in the Southern Hemisphere through a detailed description of Eliberidens species. The cladistic analysis supports the monophyly of the taxon Eliberidens by two synapomorphies: presence of geniculate chaeta with short distal end in the first parapodia and the absence of maxillary plates of superior row. The genus is a sister group of the clade formed by all dorvilleids included in the present analysis, excluding Gymnodorvillea.