Molecular phylogenetic classification of scleractinian corals from Weizhou Island, China

Scleractinian corals play important roles in the maintenance and restoration of coral systems. However, the evolutionary relationships among species remain unclear, mostly due to the limitations of traditional coral classifications because of their ecophenotypic variation and morphological plasticity. Thus, here we aimed to reconstruct the phylogenetic relationships of corals through single- and multi-gene analyses based on 116 colonies (14 families and 49 species) from Weizhou Island, China, and five molecular markers (CO1, 16S rRNA, 12S rRNA, H3, and ITS). The results reveal four cryptic species (Platygyra pini, Platygyra verweyi, Psammocora nierstraszi, and Coscinaraea columna). In single-gene analyses, mitochondrial genes can classify taxa at the family but not genus level, and vice versa for nuclear genes. Species are divided into complex and robust corals based on multi-gene analysis. Within robust corals, Merulinidae (Group XVII) is classified into eight subclades, and Dipsastraea, Favites, and Goniastrea are polyphyletic. Complex corals comprise the monophyletic Acroporidae (VI), Agariciidae (VII), Euphylliidae (V), Porites (III), and Dendrophylliidae (II). Notably, Turbinaria peltata is highly divergent from its congeners and clusters. Multi-gene analysis proved to be more accurate than single-gene analysis in elucidating phylogenetic relationships among corals. This study enhances our understanding of the diversity, evolution, and conservation of corals from Weizhou Island.