Species diversity of genera Peronia, Wallaconchis and Onchidella (Gastropoda: Onchidiidae) in intertidal coral reef environments of the Ryukyu Islands

Three genera of the family Onchidiidae, Peronia , Wallaconchis and Onchidella , are known to inhabit intertidal coral reef environments in the Ryukyu Islands, however, there have been only limited studies on their diversity. This study conducted surveys around 11 islands and 40 intertidal areas of the Ryukyus, elucidating species diversity utilizing DNA barcoding of specimens. Molecular data indicated that intertidal coral reef areas of the Ryukyu Islands harbor at least eight Onchidiidae species from three genera. The highest species cohabitation in the same intertidal areas was observed around Okinawa-jima Island; five species from three genera. Peronia spp. were found from all sites investigated in this study and the distribution ranges of four species of Peronia in the Ryukyu Islands were updated from past research. Three species of Wallaconchis ; W. ater , W. nangkauriensis , and Wallaconchis sp., were found in intertidal coral reef environments, mostly in flat areas with small rubble and rocks. Onchidella sp. inhabited intertidal areas and was found on many more islands of the Ryukyus than previously had been documented. All Onchidella sp. specimens collected from the Ryukyus were genetically distinct from described species. This study enhances the understanding of Onchidiidae diversity in intertidal coral reef environments of the Ryukyu Islands, providing a baseline dataset for better conservation of this understudied group.