Mating in the Capsalid Monogenean Benedenia seriolae, a Skin Parasite of the Yellowtail, Seriola quinqueradiata, in Japan

Mating is described for the first time in a member of the genus Benedenia, namely in Benedenia seriolae from the skin of the yellowtail Seriola quinqueradiata, and is compared with mating in the related monogenean, Entobdella soleae. In adult specimens of B. seriolae separated from the host and attached to glass, mating is brief, the penis of one hermaphrodite individual being inserted into the relatively spacious vestibule of the vagina of the co-copulant and vice versa. There is no spermatophore similar to that attached externally during mating in E. soleae. After separation, the same two individuals of B. seriolae can sometimes be induced to mate for a second time within a few minutes, by pushing the parasites together. The reproductive system of the parasite is re-described.