DNA Barcoding of Arius Species (Siluriformes: Ariidae) in Laguna de Bay, Philippines Using the Cytochrome C Oxidase Subunit I Gene

Kanduli, a local name for fishes of the Family Ariidae in the Philippines, is an economically important fish in the country. Two species of kanduli, Arius manillensis and Arius dispar, were sampled from Laguna de Bay. These were sequenced for the 655-bp region of the mitochondrial cytochrome c oxidase subunit I gene (COI). Twenty-two sequences were generated: 14 for A. manillensis and eight for A. dispar. Thirty (30) additional COI sequences of fishes belonging to Family Ariidae, namely, those of A. arius, A. graeffei, A. jella, A. maculatus, A. midgleyi, A. subrostratus and Netuma thalassinus, were obtained from GenBank and Barcoding of Life Data Systems (BOLD). A neighbor-joining tree of the 52 COI sequences was generated using the Kimura 2-parameter model. The tree was not able to distinguish between A. manillensis and A. dispar. The mean interspecific distance between these two species was not even higher than the intraspecific distance within each of them. This finding suggests that they constitute only one species, or that introgression occurred between the two species. Although the neighbor-joining tree distinguished between A. arius and A. maculatus, the distance between them was low. The COI sequence of A. jella diverged from that of the rest of the Arius species and was more similar to that of N. thalassinus. These data warrant a review of the taxonomy of the Family Ariidae.