宮城県伊豆沼産コイから採集されたチョウと東北地方におけるエラオ類の記録

Morphological characters of female and male Argulus japonicus Theile, 1900 are reported using three specimens (one female and two males) collected from a common carp Cyprinus carpio Linnaeus, 1758 (Cypriniformes: Cyprinidae) in Lake Izunuma (38º43’09″N, 141º06’09″E), Miyagi Prefecture, northern Honshu, Japan. The specimens are particularly characterized by the first pair of legs each with a single plumose seta on the posterior margin of the coxa and 46–51 supporting rods per first maxilla. These characters are useful to differentiate A. japonicus from a morphologically similar species Argulus coregoni Thorell, 1864, that also occurs in the inland waters of the same prefecture. This paper compiles the records of fish disease-causing argulid branchiurans from northern Honshu published between 1982 and 2017. These branchiurans were mostly found on common carp, but they have not been identified based on morphological and/or molecular features.