2021 年 23 巻 1 号 p. 17-35
About 80 species of Acropora corals have been recorded in Japan to date. However, there are few information on its diversity in Amami-Oshima Island, which is located in the northern part of the central Ryukyu Islands. Multiple studies, including molecular work, have looked at the species diversity of Acropora in Japan, but many of them have not been effective in successful differentiation at the species. This is the first study reporting the species diversity and molecular phylogeny of the Acropora species in Amami-Oshima Island. We collected 89 Acropora specimens, including 26 species within reef lagoon in the southwestern area (Funakoshi) of the island. We recorded A. spathulata for the first time in Japan, and A. acuminata and A. papillare for the first time in the Amami Islands. For eight species that were uncommon or difficult to identify, we described their morphological characteristics. To infer the phylogenetic relationships between the Acropora species in Amami-Oshima Island and Japan, we also reconstructed the phylongey of the specimens using a mitochondrial putative control region including published DNA data from other Japanese specimens. The results showed that Acropora species were genetically separated into seven clades. As previously reported, A. hyacinthus and A. cytherea were highly polyphyletic; nonetheless, most species were included in specific clades. In combination with previously published ecological data, the present data allowed us to propose a new species grouping (eight groups) for 36 Japanese Acropora species, which have morphological, molecular phylogenetic, and ecological similarities. This grouping will help identify the species and understand the species diversity of Acropora until a formal taxonomic revision of the genus is conducted.