Abstract / Introduction / Summary:
An adult female of Argulus coregoni Thorell, 1864 was collected from the body surface of a Sakhalin redfin Pseudaspius sachalinensis (Nikolskii, 1889) in the Hiranosawa Creek in Akita Prefecture, northern Japan. This represents a new host record for A. coregoni, and Sakhalin redfin is the second leuciscid host of this parasite. The specimen of A. coregoni is briefly described: it is characterized by three and four plumose setae near the posterior margin of the first leg coxa and 64 and 65 supporting rods in the marginal membrane of the first maxilla. The creek is a small mountain stream in a humid subarctic climate, and the water was running and very clear. Salmonids were dominant in the creek, where they most probably serve as the major hosts for A. coregoni. The climate and water conditions of the creek are inferred to provide both salmonids and A. coregoni with favorable habitats.
