Detection of a highly divergent population structure and identification of a cryptic species in the East Asian dogwhelk Nucella heyseana

The dogwhelk (genus Nucella) includes intertidal carnivorous snails that are widely distributed on the North Pacific and North Atlantic coasts. There is little knowledge on the taxonomy of Nucella species in East Asia, and classification, naming and description of East Asian Nucella species is far from being established. We performed population genetics analyses on Japanese Nucella spp., including samples from the continental coast of the Sea of Japan. We used microsatellite DNA markers and mtDNA-COI sequencing to determine the species composition, the species' classification status, and the population structure within the species. The specimens were genetically divided into 2 species, Nucella heyseana and the cryptic N. freycineti. In addition, N. heyseana was found to exhibit a highly divergent population structure among localities, which is attributable to 2 possible factors: direct development and ocean currents. These findings provide new insights into the taxonomy of East Asian Nucella species and management strategies for intertidal organisms of this region.