Anoplodiscus tai sp. nov. (Monogenea : Anoplodiscidae) from Cultured Red Sea Bream Pagrus major

Abstract

The monogenean Anoplodiscus tai sp. nov. collected from the fins of red sea bream Pagrus major cultured in Nagasaki Prefecture, Japan is described. The new species is most similar to A. richiardii Sonsino, from Pagrus orphus in the Mediterranean reported in 1890, from which it can be distinguished by a considerably smaller body size and a larger cirrus accessory piece.
Gross signs of heavily infected fish included emaciation of body and partial loss of fins. Histologically, the parasite attached firmly to the basal membrane, and the epithelium was eroded at the site of attachment. Epithelial hyperplasia was evident around the parasite. Elevation of host tissue, associated with massive cell infiltration, beneath the haptor was a common feature. This was due to sucking and pinching function of the haptor. In some cases, a portion of dermal tissues which the parasite grasped was partly torn off, and remaining tissues were distorted and necrotic. Such pathological changes may eventually lead to partial loss of fins.