Population genetic structure of the grass puffer (Tetraodontiformes: Tetraodontidae) in the northwestern Pacific revealed by mitochondrial DNA sequences and microsatellite loci

Abstract

The genus Takifugu comprises approximately 25 species that are closely related due to fairly recent speciation in the northwestern Pacific. The variety of coloration patterns within Takifugu has led to taxonomic confusion. A recent study treated Takifugu niphobles (Jordan and Snyder, 1901) as a junior synonym of Takifugu alboplumbeus (Richardson, 1845) based on morphological comparison of the type specimens. In an attempt to review the taxonomic status of grass puffer at a molecular level, 209 individuals from nine localities in the northwestern Pacific (two localities in the East Sea, five in the Korea Strait, and two in the Yellow Sea) were analyzed using mitochondrial DNA (mtDNA) and microsatellites. The mtDNA sequence analyses showed two distinct lineages (Kimura-two-parameter distance = 1.5–2.6% and 2.2–3.6% in cytochrome c oxidase subunit I and cytochrome b, respectively). The distributions of the two lineages tended to be separated; lineage 1 was located in the East Sea and lineage 2 in the Yellow Sea, but both lineages in the Korea Strait. STRUCTURE analyses using 13 microsatellite markers showed two distinct groups, which was consistent with the two subdivisions in mtDNA, except for the western Korea Strait. Our findings suggest that T. niphobles is a distinct species differing from T. alboplumbeus, unlike previous study. This requires further careful taxonomic revision.