Abstract / Introduction / Summary:
An ovigerous female and an immature male of a cymothoid isopod, Mothocya parvostis Bruce, 1986 were found in the branchial cavity of a Japanese halfbeak, Hyporhamphus sajori (Temminck and Schlegel, 1846) (Beloniformes: Hemiramphidae), sold at a local supermarket in Kashiwa, Chiba Prefecture, Japan. The label of the fish indicates that it was caught in Aichi Prefecture. Mothocya parvostis is widely distributed in the temperate waters around Japan, however, there are no records based on adult specimens in Aichi Prefecture. Therefore, this finding represents the first reliable record of M. parvostis in this prefecture.
