New genus and species record of reef coral Micromussa amakusensis in the southern South China Sea

Abstract

BackgroundRecent taxonomic revisions of zooxanthellate scleractinian coral taxa have inevitably resulted in confusion regarding the geographic ranges of even the most well-studied species. For example, the recorded distribution ranges of Stylophora pistillata and Pocillopora damicornis, two of the most intensely researched experimental subjects, have been restricted dramatically due to confounding cryptic species. Micromussa is an Indo-Pacific genus that has been revised recently. The revision incorporated five new members and led to substantial range restriction of its type species and only initial member M. amakusensis to Japan and the Coral Triangle. Here, we report the presence of Micromussa amakusensis in Singapore using phylogenetic methods.ResultsA total of seven M. amakusensis colonies were recorded via SCUBA surveys at four coral reef sites south of mainland Singapore, including two artificial seawall sites. Colonies were found encrusting on dead coral skeletons or bare rocky substrate between 2 and 5 m in depth. Morphological examination and phylogenetic analyses support the identity of these colonies as M. amakusensis, but the phylogeny reconstruction also shows that they form relatively distinct branches with unexpected lineage diversity.ConclusionsOur results and verified geographic records of M. amakusensis illustrate that, outside the type locality in Japan, the species can also be found widely in the South China Sea. Moreover, our discovery provides a new genus and species record in Singapore and represents the southern-most occurrence of the species in the Indo-Pacific. Despite the extensive survey efforts in Singapore over the last three decades, taxonomic studies integrating morphological and molecular methods remain instrumental in quantifying the actual coral species diversity.