DNA Barcode Identification for Gastropod and Bivalve Species in Coastal Bays and Islands of Vietnam

Vietnam, a coastal and tropical country, harbors a high diversity of marine mollusks, particularly gastropods and bivalves. However, the taxonomy of these groups is frequently confounded by their morphological similarities and pronounced plasticity. The aim of this study was to assemble the first comprehensive barcode reference library for marine gastropods and bivalves in Vietnam. The samples were collected from four different marine areas. We identified 31 morphospecies belonging to 28 genera, 24 families, and 11 orders. A total of 49 COI-5P sequences were obtained and categorized into 31 taxa (30 to species levels), 83.67% of which were found to be concordant with morphology-based identifications. The topology of Neighbor-Joining trees also grouped the sequences of the same species into monophyletic clusters, which were congruent with 31 taxa. Twenty eight species were placed in single Barcode Index Numbers (BINS) and three in two BINs. Barcode gaps were found for all species. As a result, the obtained COI-5P barcodes are suitable for species identification of 17 gastropod species and 14 bivalves. All COI-5P barcodes have been deposited in GenBank, BOLD, and the website for the national project “Development of DNA Database for Valuable Marine Invertebrates”.