Abstract
To examine species composition and population structures in sand lance (Ammodytidae) along the northern Pacific coast of Japan, genetic analysis were carried out for specimens collected in 2014 from Otsuchi Bay, Iwate, Ishinomaki Bay, Miyagi, off Soma, Fukushima and Ise–Mikawa Bays, Aichi. The samples consisted of Ammodytes japonicus and Ammodytes heian , of which the latter is a recently described species. Neither species exhibited significant genetic differences among localities. Only A. japonicus was found in the most southern locality at Aichi, but it decreased northward to A. japonicus and A. heian with modes of 65 and 63, respectively, but this characteristic did not differ significantly within a locality (Iwate). This suggests that the vertebral counts of Ammodytes spp. in Japanese waters are probably strongly determined by the environment than by a species‐specific genetic trait.