Abstract
In the present study, the morphology and morphometric characterization of four species of monogenean gill parasites infecting the skin and gills of Oreochromis niloticus belonging to family Cichlidae collected from the River Nile at Giza governorates, Egypt were described by means of light microscopy. Thirty six out of 68 specimens of this fish were found to be naturally infected at a rate of 53%. Two Cichlidogyrids (family: Ancyrocephalidae) and one Gyrodactylid (family: Gyrodactylidae) were identified. CIchlidogyrus tilapiae Paperna, 1960 was characterized by a copulatory organ found in the midline of the body, with accessory sclerite situated roughly parallel with the copulatory tube and never seen completely isolated from it. In all worms examined, the proximal end of the accessory sclerite was found in contact with the base of the copulatory tube, indicating that there was a connection between the base of the copuatory tube and the proximal part of the accessory sclerite. Cichlidogyrus longicornis longicornis which was characterized from all species of this genus by having two long projections of the complex bar and its copulatory organ had a slightly long ejaculatory tube. Cichlidogyrus tubicerrus magnus possessed a haptor with two pairs of anchors, its ventral anchor was attached to the V-shaped bar that had a number of tooth - like projections on the inner margin. The dorsal anchor was attached to a complex bar (dorsal bar), which consists of three articulated pieces. The central piece was slightly bent and the other two pieces were attached to the central one in such away that their points of attachments divide the bar in three equal parts. Gyrodactylus cichlidarum Paperna, 1968 possessed a haptor resembled a cub holding a variety of hamuli, bars and supportive additional sclerites. The hamuli withdrawn inside a transparent tegumental sheath, the hamulus blade emerged from an opening decorating the distal area of a cone-shaped, transparent, tegunental sheath. Oreochromis niloticus fish represents a normal host for all these species except for Cichlidogyrus tubicerrus magnus which represented as a new host for this parasite. These species were redescribed by using light micrographs, line drawings and measurements which can be used as a guide material for the identification of these species by following researchers. [Kareem Morsy; Fathy Abdel-Ghaffar; Abdel-Rahman Bashtar; Mohamed Shazli; Hamed Fayed; Faten Adel. Redescription of Three Cichlidogyrids (Monogenea: Ancyrocephalidae) and One Gyrodactylid (Monogenea: Gyrodactylidae) Infecting Oreochromis Niloticus (Cichlidae) From The River Nile. Life Sci J 2012;9(3):2600-2611] (ISSN:1097-8135). http://www.lifesciencesite.com. 377