Lernaea cyprinacea Linnaeus, 1758, is reported based on specimens from two species of freshwater fishes, medaka, Oryzias latipes (Temminck and Schlegel, 1846) (Beloniformes: Adrianichthyidae) and stone moroko, Pseudorasbora parva (Temminck and Schlegel, 1846) (Cypriniformes: Cyprinidae), caught in a concrete-lined irrigation ditch at Kuroi-jinden-kami, Toyoura, Shimonoseki, Yamaguchi Prefecture, western Honshu, Japan. This represents the first specimen-based record of L. cyprinacea from the prefecture. Medaka were more frequently infected than stone moroko (prevalence, 39.1% vs. 4.8%), and the intensity of L. cyprinacea ranged from 1–5 (mean, 2.0) and was 2 (2.0) in these fish species, respectively. Some individuals of L. cyprinacea infecting medaka were found to be attached by an unidentified filamentous green alga on their body surface.

山口県産ミナミメダカとモツゴに寄生していたイカリムシと その体表に着生した緑藻類(長澤和也・久志本鉄平)