A New Asteroid (Echinodermata, Astropectinidae) and Ophiuroid (Echinodermata, Hemieuryalidae) from the Mid-Cretaceous of Southern Japan

Abstract

Fairly well-preserved external molds of articulated starfish and brittle stars from the upper Albian (mid-Cretaceous) Hokahira Member of the Enokuchi Formation (Goshoura Group) in Goshoura Island (Kumamoto, southern Japan), are described as new species; Coulonia hokahira sp. nov. and Ophiozonella tumidasquama sp. nov., respectively. Of Coulonia, three Early to mid-Cretaceous species are known to date from Texas (USA), Europe and North Africa. The new Japanese species differs from two of these (C. reidi and C. platyspina) in having a proportionally narrower marginal border, and from the third (C. neocomiensis) in having a broader disk. With regard to the brittle stars, it can be stated that the three extinct species previously assigned to Ophiozonella (O. stoehrae, O. eloy and O. thomasi), from Barremian and Aptian (Lower Cretaceous) strata in Europe and the USA, differ from O. tumidasquama sp. nov. in having four spine articulations on lateral arm plates.