The taxonomy of Gyrodactylus (Monogenea) parasitizing certain salmonid fishes of North America, with a description of Gyrodactylus nerkae n. sp.

Abstract

Specimens of Gyrodactylus Nordmann, 1832, both newly collected and deposited type material, from cultured and wild salmonid fishes from various localities in North America, are compared and five species are recognized: G. salmonis Yin and Sproston, 1948 status emended, on Salmo clarki, S. salar, S. aguabonita, S. gairdneri, S. trutta, Salvelinus fontinalis, S. namaycush, and Oncorhynchus kisutch from several localities throughout the continent; Gyrodactylus nerkae n. sp. on O. nerka from Vancouver Island; G. colemanensis Mizelle and Kritsky, 1967 on Salmo gairdneri from California, Arkansas, and insular Newfoundland, S. fontinalis from Nova Scotia and Ontario, and S. trutta, S. namaycush, and S. fontinalis × S. namaycush from Ontario; G. avalonia Hanek and Threlfall, 1969 on S. gairdneri from Nova Scotia; and G. brevis Crane and Mizelle, 1967 on S. gairdneri from California. Gyrodactylus salmonis, G. nerkae, and G. colemanensis are considered specific to salmonid fishes, whereas G. avalonia and G. brevis are considered "accidental" infections, acquired from nonsalmonid fishes. A diagnostic key to the five species is provided and gyrodactyliasis, as a disease of cultured salmonids in North America, is discussed briefly.