A taxonomic review of the genus Astrocladus (Echinodermata, Ophiuroidea, Euryalida, Gorgonocephalidae) from Japanese coastal waters

Japanese species of the genus Astrocladus (Echinodermata, Ophiuroidea, Euryalida, Gorgonocephalidae) are reviewed. Astrocladus coniferus recently has two junior synonyms, A. dofleini Doderlein and A. pardalis Doderlein, however, status of these species has long been questioned. These species concepts have not been reviewed in recent years and no molecular phylogenetic analyses have been performed. Observations of the lectotype of A. coniferus, as well as the lectotype and four paralectotypes of A. dofleini and the holotype of A. pardalis have revealed that A. coniferus and A. pardalis are conspecific and morphologically distinguishable from A. dofleini. Astrocladus coniferus and A. dofleini are supported as distinct species by our molecular data. Additionally, we re-describe A. exiguus and A. annulatus, based on recently collected specimens and the holotype. We conclude that four species, A. annulatus, A. coniferus, A. dofleini, and A. exiguus are present in Japanese waters.