Diversity of Zoantharia (Anthozoa: Hexacorallia) at Dongsha Atoll in the South China Sea

Dongsha Atoll is the largest coral atoll in the South China Sea (SCS), and is expected to harbor high levels of biodiversity as the SCS is located adjacent to the recognized center of maximum marine biodiversity in the central Indo-Pacific (CIP). However, due to its relative isolation, the biodiversity of Dongsha Atoll has not yet been well investigated for most marine taxa. In this study, we report on findings from our survey in 2016 that focused on the order Zoantharia, for which only sporadic previous reports exist from the SCS. Our results indicate some species such as Palythoa tuberculosa are very common around Dongsha Atoll, as well as the presence of at least three undescribed species, including one species only found thus far at the atoll. Overall, we recorded 16 species of Zoantharia from Dongsha Atoll, bringing the total number of zoantharian species in the SCS to 22, close to numbers reported from the CIP (=24 spp.) and southern Japan (=28 spp.). These findings demonstrate the importance of protecting the biodiversity of Dongsha Atoll, and also, given the limited survey coverage, the potential for undiscovered biodiversity in the SCS.