Seven species of Gyrodactylus (Monogenea: gyrodactylidae) from Plecoglossus altivelis (plecoglossidae), Cyprinus carpio (Cyprinidae) and Anguilla spp. (Anguillidae).

Abstract

Descriptions and identifications are made of seven species of Gyrodactylus collected from four species of cultured freshwater fish. Three species of Gyrodactylus were obtained from the ayu (Plecoglossus altivelis); G. japonucus KIKUCHI, 1929, G. tominagai n.sp. and G. plecoglossi n.sp. G. tominagai n.sp. is closely related to G. japonicus, but may be distinguished mainly by the shape and size of the marginal book. G. plecoglossi n.sp. resembles G. japonicus and G. tominagai, but differs in the smaller anchor and different shape and size of the marginal hook. G. kherulensis ERGENS, 1974 and G. sprostonae LING, 1962 were collected from the carp (Cyprinus carpio); they are the first recorded cases in Japan. G. nipponensis n.sp. is described from the Japanese eel (Anguilla japonica). This differs in the larger anchor and the smaller sickle of the marginal hook from the most closely related species, G. anguillae ERGENS, 1960, which is redescribed for comparative study based on the specimens from the European eel (Anguilla anguilla) in England.