Abstract / Introduction / Summary:
A pair of a gravid female and a male of Ceratothoa oxyrrhynchaena Koelbel, 1878 (Isopoda: Cymothoidae) were collected from the buccal cavity of a blackthroat seaperch, Doederleinia berycoides (Hilgendorf, 1879) (Perciformes: Acropomatidae), in the western North Pacific Ocean off Kinkasan Island, Miyagi Prefecture, northeastern Japan. This expands the geographical distribution range of C. oxyrrhynchaena from off Onahama (ca. 37°N), Fukushima Prefecture, northward to off Kinkasan Island (38°17′N) and represents the first record of the species from the southern subarctic waters. Based on the previous and present records of C. oxyrrhynchaena from Japan, the species is suggested to occur in a wide area ranging from the subtropical through temperate to southern subarctic waters.