LAUSR

Abstract The marine environments surrounding the Dongsha Islands have long been considered as important fishing grounds for fishermen from China and surrounding countries. Although considerable work has been done on marine fish taxonomy of the Dongsha Islands, there is still a significant gap between our knowledge and the true fish diversity in this ocean area. Here, by analyzing the mitochondrial COI gene, we explore the fish diversity across the Dongsha Islands using a molecular taxonomic approach. In total, we identified 46 morphological species in our samples based on current taxonomical keys, yet 153 DNA barcodes using the 676 base-pair fragments of the COI gene suggested 51 putative species (belonging to 43 genera, 28 families, and 11 orders) by two DNA taxonomic approaches. The average sequence variation (K2P distance) within species was 0.33% (range 0–0.81%), while the average genetic distance between congeners was 3.43% (range 0.74–8.39%). Our results suggest that COI-based barcoding can be effectively used at a species level resolution for the marine fishes in this ocean area and that it allows a realistic idea of the fish diversity.