Benthodytes palauta, a new species of deep-sea holothuroid (Elasipodida: Psychropotidae) from the western Pacific Ocean

A new species of Psychropotidae holothuroid, Benthodytes palauta sp. nov., was collected from the Kyushu-Palau Ridge at a depth of 2 666 m. This new species is characterized by a leathery body wall, red-violet skin, five pairs of dorsal papillae, nineteen pairs of tube feet, and a narrow brim. The internal organs include one Polian vesicle, two tufts of gonads, and no respiratory trees. Ventral ossicles are large and spinous, with crosses of four arms with central bipartite apophyses. Papillae ossicles are crosses with four arms with bipartite apophyses. The dorsal ossicles were few and large, and cross-shaped with four arms and central bipartite apophyses. Tentacle ossicles were large and rod-shaped or slender rods. Gonad ossicles were primary crosses of four arms and brim ossicles were cross-shaped with spines. The phylogenetic analyses of this species support that B. palauta sp. nov. belongs to Benthodytes. Furthermore, the paraphyletic relationships were confirmed; however, a revision of the genus Benthodytes is needed to resolve its phylogenetic relationship.