A pair of an ovigerous female and an adult male of the cymothoid isopod Ceratothoa oxyrrhynchaena Koelbel, 1878 were found in the buccal cavity of a yellowback sea-bream, Dentex hypselosomus Bleeker, 1854 (Sparidae), from Tosa Bay (western North Pacific Ocean), Kochi Prefecture, Shikoku, Japan. This repre- sents the first record of C. oxyrrhynchaena from Kochi Prefecture, and the species is briefly described. The fe – male and the male were attached to the tongue and be- side the female, respectively, in the buccal cavity. Four individuals of polyopisthocotylean monogenean (Plat- yhelminthes) were found on the brood pouch of the fe- male. The biology of C. oxyrrhynchaena in Japanese waters is summarized based on the literature published between 1878 and 2020.

土佐湾産キダイから得たソコウオノエ Ceratothoa oxyrrhynchaena (等脚目ウオノエ科)と日本産ソコウオノエに関する知見の集約(長澤和也)