Abstract：To investigate the availability of using COⅠsequences as DNA barcodes to identify Gymnothorax species, partial sequences of mitochondrial cytochrome oxidase subunitⅠ(COⅠ) gene of 10 Gymnothorax speices from China sea were obtained by PCR amplification and sequencing. Combining with COⅠ gene sequence of 3 Gymnothorax species from GenBank, a total of 31 individual COⅠ sequences of 13 Gymnothorax species were obtained. Genetic distances of inter-and intra-species were calculated using MEGA 5.0 and the molecular phylogenetic trees were constructed using neighbour-joining and maximum likelihood methods. The results showed that intra-species genetic distance within the 13 Gymnothorax species were between 0.000-0.007 and the average genetic distance was 0.003; the inter-genetic distances among species were 0.005-0.243. Except for the distance between Gymnothorax pesudothyrsoideus and Gymnothorax reevesii was 0.005, inter-genetic distances among other Gymnothorax species were more than 2% and the average genetic distance was 0.187, indicating that the COⅠ gene could be used as the barcode gene for the Gymnothorax identification, but also had certain limitations. In the molecular phylogenetic tree, 13 Gymnothorax species mainly formed four branches, species Gymnothorax thyrsoideus was first separated and located at the base of the tree, indicating its lowest evolutionary status. Individuals of species G. pesudothyrsoideus and G. reevesii were crossed clustering together and could not formed each species monophyletic branch. However, there were significant differences in morphological character, excluding the possibility of synonyms, gene penetration caused by natural hybridization might exist between the two species. In addition, the COⅠ sequence of our sample Gymnothorax formosus was 5.5% different from the G. formosus obtained from GenBank, and their evolutionary status could also be clearly distinguished from the phylogenetic tree, indicating that species G. formosus sampled in this study may possibly be a new cryptic species.
2020, Vol. 33 
