Acanthostomum Spiniceps ( Digenea : Cryptogonimidae : Acanthostominae ) , a Parasite of the African Snook Lates Niloticus ( Perciformes : Latidae ) : A Light and Scanning Electron Microscopic Study

Abstract

The morphology of the adult stage of Acanthostomum spiniceps recovered from the African snook, Lates niloticus (Perciformes: Latidae) of the river Nile, Egypt was studied with both light and scanning electron microscopy.The most important morphological features differentiating this species are the number of circumoral spines, body shape, ratio of body length to width, sucker sizes, and the presence or absence of spines on the ventral sucker. Sixteen out of forty fish (40%) was found to be naturally infected with this digenetic trematode belonging to family: Acanthostominae. The infection was recorded in the intestinal wall of the host fish. Body was elongate, 1.203-2.074 mm long, maximum width 0.311-0.534 mm. Oral sucker was terminal, funnel-shaped, 0.201-0.353 mm long and 0.245-0.310 mm wide. Simple peribuccal spines 0.042-0.066 mm long. Ventral sucker was circular, 0.110-0.140 mm long, 0.120-0.204 mm wide, situated approximately at 1/3 of body length. Ratio of oral and ventral suckers was 1: 0.5. Testes tandem or slightly diagonal, located near posterior end of body being of irregular rounded shape. Size of anterior testis was 0.130-0.220 mm long, 0.314-0.358 mm wide, that of posterior testis was 0.180-0.274 mm long, 0.390-0.327 mm wide. Ovary transversely oval, smaller than testes, measured 0.102-0.166 mm long, 0.100-0.164 mm wide, situated just anterior to anterior testis. By comparison with some of the previously described species of this genus, the present one showed all morphological characters and the most morphologically similar species was A. spiniceps.