Taxonomic study on crustacean parasites of the flathead grey mullet (Mugil cephalus) and red seabream (Pagrus major) in Hiroshima Bay, Japan

Abstract

Crustacean fish parasites can be used as bio-indicators of pollution. This study examined the crustacean parasites of flathead grey mullet (Mugil cephalus) and red seabream (Pagrus major) landed at a fishing port in Hiroshima Bay. Specimens were collected from November 2015 to August 2016. Three species of parasitic crustaceans were identified. Caligus sp. (Copepoda: Siphonostomatoida: Caligidae) was collected from the gills of a male flathead grey mullet Mugil cephalus. The genus Caligus is the largest among the parasitic copepods, containing more than 250 species worldwide, and a total of 20 species have been found from marine fishes in Japan. Lernanthropus atrox Heller, 1865 (Copepoda: Siphonostomatoida: Lernaeopodidae) was collected from the gills of a female red seabream Pagrus. Copepods of the genus Lernanthropus are found attached to the gill filaments of marine fishes in the world. This species is known to occur in both Australian and Japanese waters; in Japan, it has been recorded from Tokyo Bay and the Seto Inland Sea. The cymothoid copepod Ceratothoa verrucosa (Schioedte and Meinert, 1883) (Isopoda: Cymothoidae) was found in the buccal cavity of a red seabream Pagrus major. Cymothoid isopods, including Ceratothoa verrucosa, are found in the buccal and gill cavities as well as on the body surface of fish hosts. This species is only known to occur in Japanese waters.