A preliminary account of the shallow-water echinoderms of Rodrigues, Mauritius, western Indian Ocean

Collections of echinoderms were made from the intertidal, lagoon and reef slopes of Rodrigues over a period of 3 weeks in September to October, 2001. A total of 74 species are reported here, including three species of Crinoidea, 10 species of Asteroidea, 17 species of Ophiuroidea, 15 species of Echinoidea and 29 species of Holothurioidea. These findings include 10 new records for the Mascarene Islands (Reunion, Mauritius and Rodrigues), four species (two in the asteroid genus 'Asterina', one in the ophiuroid genus Amphioplus and one species in the holothurioid genus Actinopyga) that remain unnamed due to the need to clarify unresolved taxonomic issues, and one species of crinoid which could not be identified because only the distal parts of four arms were collected. In the dendrochirotid holothurioid family Psolidae, the little-known species Psolus appendiculatus (de Blainville) 1821, P. boholensis Semper, 1868 and P. complanatus Semper, 1868 are referred to the genus Psolidium Ludwig, 1887. Despite its seniority, P. appendiculatus is treated as a (senior) synonym of the better known and described species Psolidium ornatum (Perrier, 1893). In the dendrochirotid holothurioid family Phyllophoridae, Thyonidiella cherbonnieri nom. nov. is proposed for misidentified specimens of Semperiella tenera (Ludwig, 1875) in the western Indian Ocean, and Semperiella Heding and Panning, 1954 is reduced to the synonymy of Thyonidiella Heding and Panning, 1954. In the apodid holothurioid family Chiridotidae the species Chiridota eximia Haacke, 1880 is reduced to the synonymy of C. rigida Semper, 1868. Given the small size of the area of shallow water around Rodrigues that has been sampled, the relatively small range of marine habitats present and the geographic isolation, this is an impressive diversity. The biogeography of the 69 identified species of Rodrigues is discussed.