Molecular phylogenetic relationships of some common sweetlips (Haemulidae: Plectorhynchinae) and the synonyms controversy of two Plectorhinchus species.

Molecular phylogenetic topologies from 40 individuals of 17 sweetlips were constructed based on the mitochondrial cytochrome b (cyt b) and cytochrome c oxidase subunit I (COI) genes. All phylogenetic results strongly revealed the division of the sweetlips into three morphological distinct groups. Group I: sweetlips with colorful patterns, Group II and Group III: species with uniformly dark patterns. The relationships of those morphologically confused Plectorhinchus species were well-resolved in the phylogenetic results. We also confirmed that the genus Diagramma was placed inside the colorful Plectorhinchus groups, suggesting close relationship of Diagramma within Plectorhinchus. Additionally, we found that two species, P. orientalis and P. vittatus, which were traditionally considered as synonyms for oriental sweetlips, which were suggested to be two distinct species. Sequence divergence also revealed a great genetic variation between P. orientalis and P. vittatus (6.0% in Cyt b and 7.4% in COI), which was largely greater than the species diagnosis divergence value (2%) suggested by Hebert et al. This new finding suggested P. orientalis and P. vittatus might be two distinct species and should not be placed as synonyms.