Taxonomic revision of the genus <i>Echinaster</i> (Spinulosida: Echinasteridae) in Japanese waters

Abstract The genus Echinaster in Japanese waters was revised, resulting in the discovery of two new species, E. crystallus n. sp. and E. toyoshiomaruae n. sp., and one newly recorded species, E. stereosomus , from Japan. Molecular phylogenetic analyses including 22 echinasterid species indicate that another newly recorded species, Metrodira subulata , is grouped with the other Echinaster species. Since the revised diagnostic characteristics of the genus Echinaster are consistent with the morphology of Metrodira , we newly synonymize this genus with Echinaster . Consequently, the genus Echinaster includes six species in Japanese waters. Morphological descriptions of all Japanese Echinaster species were provided.