A new species of Ophiuroidea, Ophiacantha scissionis sp. nov., is described. It was collected from Munseom Island, Jeju-do, South Korea at a depth of 28-36 m, by SCUBA diving. Ophiacantha scissionis has unique and distinct morphological characteristics: small disk, densely covered by small trifid spines, radial shields completely concealed by disk spines, six arms with four arm spines proximally, fissiparous. In addition, this species is clearly distinguished from other species of Ophiacantha by mitochondrial COI. This species is usually hexamerous and reproduces asexually by fissiparity. It is the first report of fissiparous reproduction in the genus Ophiacantha.
Keywords: Brittle stars; Mitochondrial COI; Ophiacanthidae; Phylogeny; Taxonomy.