Surface features of the monogenean gill parasites Pseudodactylogyrus anguillae and Pseudodactylogyrus bini from the European eel Anguilla anguilla in Egypt.

In the present study, scanning electron microscopy is used to demonstrate the surface features of Pseudodactylogyrus anguillae Yin and Sproston (1948) Gussev, 1965 and Pseudodactylogyrus bini Kikuchi (1929) Gussev, 1965 from the European eel Anguilla anguilla. Specimens of the eel A. anguilla were collected from the River Nile, near Mansoura, Dakahlia Province, Egypt. Morphologically, P. anguillae could be distinguished from P. bini based on the total length, the shape and size of the haptor, and the constriction between the haptor and body proper. The general body tegument and the haptoral tegument of both species are microvillous. Possible functions of the microvilli associated with the tegument covering the anterior adhesive areas are discussed. The region of the body proper just anterior to the haptor of P. anguillae, appears to be highly folded and provided with many projections forming scale-like structures. Many surface ciliary sensilla presumed to be sensory structures are found on the tegument of the anterior adhesive area of P. anguillae. Secretory bodies and mucus-like substances are recorded on the tegument covering the anterior adhesive areas of P. anguillae and the haptor of P. bini. The possible role of these secretions in the attachment of the anterior adhesive areas and the posterior attachment haptor to the host tissues are also discussed.