In the present study, scanning electron microscopy revealed that the anterior attachment organ of Schilbetrema aegyptica consists of four head lobes, two on each side of the body. There are two types of secretion; red-shaped bodies and mucoid-like secretory bodies. The dorsal and ventral body surface showed transverse tegumental folds that are wider on the ventral side. The transverse tegumental ridges covering the dorsal surface of the middle region of the body was characterized by finger like projections, a feature which was found to be absent in other body regions. Two types of presumed tegumental sense organs, ciliary-like sensilla and dome shaped papilla were detected. The ciliary sensilla were more numerous than the dome-shaped papilla and distributed all over the body surface while the dome-shaped papilla were concentrated on the ventral and dorsal tegument of the anterior head region, as well as the ventral surface of the haptor. Regarding the site of attachment, some individuals of the parasite attach their haptors between two adjacent secondary gill lamellae while others were found attaching their haptors to the primary gill lamellae. In both cases, the hamuli and some marginal hooklets were inserted into the tissues of the host. A remarkable depression was observed in association with the established haptor of S. aegyptica on the gill tissues of the host.
Key words: Schilbe mystus, monogenea, Schilbetrema aegyptica, SEM, River Nile, Egypt
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