Heterobothrium lineatus (Monogenea: Diclidophoridae) infecting the gills of the Nile puffer Tetraodon lineatus (Pisces: Tetraodontidae) from the River Nile, Egypt with a new localit record: a light and scanning electron microscopic study.

Heterobothrium lineatus (Monogenea: Diclidophoridae) is described from the gills of Tetraodon lineatus collected from the River Nile at Helwan governorate, Egypt as a new locality record. The morphology and morphometric characterization of the recovered worms were described by means of light and scanning electron microscopy. Twenty two out 35 with a percentage of 62.9% of the examined fish were infected with Heterobothrium sp. (the intensity of infection was about ten worms per fish in general). Most of the infected fish had very pale gills and showed symptoms of anemia. Morphologically, the adult worms were elongated with anterior pointed and posterior broad ends, it measured 1.15-1.76 (1.52 +/- 0.02) mm in length x 0.28-0.39 (0.29 +/- 0.02) mm in width. Two buccal organs situated anteriorly around mouth opening were shown by light and scanning electron microscopy. Haptor subdivided into four pairs of clamps without isthmus separating it from body. The recovered worm differed from the previously species in the same genus by small dimensions of the measurements and presence of a copulatory organ armed with 7-11 genital hooks. Also, it is distinguished from H. tetrodonis and H. okamotoi by absence of a distinct isthmus, and resembled H. lamothei from gills of Sphoeroides testodineus in Mexico and H. lineatus from T. lineatus in Egypt in general appearance and presence of rectangular haptor with the fourth pair of clamps smaller than the previous ones.

Ultrastructural studies of the spermatogenesis and spermiogenesis of the caryophyllidean cestode Wenyonia virilis (Woodland, 1923).

Spermatogenesis and spermiogenesis of the monozoic caryophyllidean cestode Wenyonia virilis (Woodland, 1923), an intestinal parasite of Synodontis schall (Pisces: Siluridae), have been investigated by means of transmission electron microscopy for the first time in Egypt. Spermatogenesis is of a rosette type; each spermatogonium undergoes four mitotic and two meiotic divisions resulting in the formation of sixty four spermatids. These spermatids undergo spermiogenesis and transform into mature spermatozoa. The process of spermiogenesis begins by the formation of the zone of differentiation, at one end of the spermatid cell, with one pair of centriole but without an intercentriolar body. The left-handed centriole, firstly, forms a basal body but aborts forming a flagellar bud. The right-handed one develops externally into an axoneme growing parallel to a cytoplasmic extension protruding from the differentiating zone. The nucleus penetrates this extension followed by the proximodistal fusion of the axoneme in the sperm shaft. The spermatozoon of W. virilis lacks mitochondria and consists of five regions showing gradual increase in the nucleus width and the presence of glycogen granules. Some important differences between the present study and others done on monozoic and polyzoic worms are recorded and discussed.