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

Pseudodactylogyrus anguillae (Yin & Sproston, 1948) from the giant mottled eel Anguilla marmorata Quoy & Gaimard, 1824, in the Phongolo River, South Africa: an invader on the African continent

The global invasive anguillid gill parasite Pseudodactylogyrus anguillae (Yin and Sproston, 1948) has only recently been documented from eels in South Africa. As there is no known eel trade in South Africa, the source of introduction of this parasite has been debated, and its status as an alien parasite was rendered uncertain. We report on the first infection of Pseudodactylogyrus anguillae from the giant mottled eel Anguilla marmorata from the Phongolo River (South Africa) using classic morphological and molecular methodologies and clarify the introduction status category of this parasite as alien and invasive.

Scanning electron microscope observations on the monogenean parasite Paraquadriacanthus nasalis from the nasal cavities of the freshwater fish Clarias gariepinus in Egypt with a note on some surface features of its microhabitat

Surface features of the monogenean Paraquadriacanthus nasalis Ergens, 1988 (quoted by Kritsky, 1990) inhabiting the nasal cavities of the freshwater fish Clarias gariepinus were studied for the first time using scanning electron microscopy. The anterior adhesive areas possess two slit-like openings. Many small openings were detected on the tegument covering the anterior-most region of the head. Some considerably large openings were also found in the median region between the two slit-like openings of the adhesive sacs. A transverse slit-like mouth opening with two lip-like structures was detected on the ventral surface of the body. Three types of presumed sensory structures were found associated with the tegument of the anterior adhesive area and anterior region of the body. These are surface ciliary sensilla, dome-shaped structures, and many spherical structures. The possible functions of these presumed sensory structures were discussed. The tegument covering the anterior adhesive area lacks microvilli, while the tegument covering the haptor is associated with microvilli. The haptoral sclerites were found in two different positions. Some surface features of the nasal cavities of C. gariepinus (microhabitat of P. nasalis) were also studied using scanning electron microscopy. Many lamellae-like and spine-like structures were recognized. The epithelium lining in some regions of the nasal cavities has small and large openings and covered with mucus. The possible roles of some haptoral sclerites in the attachment of the parasite to the host tissues were discussed.