THE DNA BARCODING, CLASSIFICATION, AND PHYLOGENY OF INDO-WESTERN PACIFIC PLECTORHYNCHINAE

To explore whether COⅠsequences could be used as the DNA barcodes in the identification of Plectorhynchinae species, we analyzed the 651 bp COⅠsequences from 51 individuals of 18 Plectorhynchinae fish in this study. The genetic distances between and within species were calculated using MEGA 5.0, and the molecular phylogenetic trees were constructed using the maximum likelihood and Bayesian inference methods. The results showed that the average inter-species genetic distance (0.142) was 47 times higher than the average intra-species genetic distance (0.003). All the interspecies genetic distances were larger than the minimum value 0.020 (2%) suggested by Hebert for the species identification. In the molecular phylogenetic trees, each individual of the same species could form an independent monophyletic group, indicating that COⅠcould be potentially used as an effective barcode gene in the rapid and accurate identification of Plectorhynchinae species. According to the genetic distance values, we found that two Plectorhinchus species, P. orientalis and P. vittatus which were conventionally regarded as synonyms, could be actually two distinct species because of their large COⅠgenetic variations (0.070). The average genetic distance between Diagramma and Plectorhinchus was lower than the values of intra-Plectorhinchus species, which implied that the genetic variation between Diagramma and Plectorhinchus might be below the significant level. This supported the notion that Diagramma could be classified into the Plectorhinchus genus.