Taxonomic characterization of <i>Tanakia</i> species (Acheilognathidae) using DNA barcoding analyses

<p><i>Tanakia</i> is a bitterling genus with six species found in Far East Asia. Our aim was to construct the standard DNA barcode database available for the identification of six <i>Tanakia</i> species by comparing the range of intra- and inter-specific genetic distances, identifying the phylogenetic placement of each <i>Tanakia</i> species and providing the unique barcode characteristics that are specific to each species, using cytochrome oxidase I (COI) and cytochrome b (cyt <i>b</i>). Both loci failed to create a perfect barcoding gap between the ranges of inter- and intra-specific genetic distances, though interspecific COI distances were sufficiently greater than intraspecific values with only a few exceptions. In our phylogenetic analyses, <i>T. koreensis</i> and <i>T. signifer</i> did not form a monophyletic cluster of haplotypes in both loci. COI provided clear nucleotide characteristics that distinguish each species, whereas relatively fewer informative sites were found within the range of cyt <i>b</i>. Overall, COI could be regarded as appropriate species identification solution in <i>Tanakia</i>. Our analyses yielded some taxonomic issues that need the further investigation, and are expected to be helpful in the examination for the conservation status of <i>Tanakia</i> species that are on the verge of being endangered.</p>