A New Asterinid Sea Star, Disasterina akajimaensis (Echinodermata: Asteroidea) from the Ryukyu Islands, Japan, with Notes on the Genus Disasterina

A new asterinid, Disasterina akajimaensis sp. nov., is described from a specimen collected at Akajima Island, the Ryukyu Islands, Japan. It is clearly distinguishable from its five congeners by the following diagnostic characters: body relatively low and flat, uncalcified interradial areas conspicuous on ventral interradii, papulae numerous in center of disc, abactinal plates mostly lacking spinelets, inferomarginal plates with 2-4 spinelets, actinolateral plates with 1 spine, oral plates with 4-5 oral spines and no suboral spine, adambulacral plates with 1-3 furrows and 1 subambulacral spine. This is the first report of this genus from Japanese waters. Notes on the genus Disasterina and a tabular summary of the characters of the currently known species are also given.