Surface Morphology of Echinostoma revolutum (Digenea: Echinostomatidae): Excysted Metacercariae
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Abstract
The surface ultrastructure of Echinostoma revolutum (Digenea: Echinostomatidae), obtained from freshwater snails, Filopaludina spp., naturally infected with the metacercariae, was studied by scanning electron microscopy. The excysted metacercaria was elongated, ventrally concave and pointed posteriorly. The anterior half body surface was covered with numerous peg-like tegumental spines. The oral sucker was circular and was situated subterminally at the antero ventral side of the body. The lip of the oral sucker was devoid of spines. The lip of oral sucker exhibited wrinkled cytoplasmic processes and had ciliated knob-like structure papillae. The head crown was surrounded by 37 retractable, horseshoe-shaped collar spines, which were embedded in cytoplasmic pockets. The ventral sucker was medial at one third of the body. The excretory pore was terminal, and showed a smooth tegument. A number of the ultrastructural features revealed may prove to represent taxonomically informative characters, some of which may be useful at the genus and species level.
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References
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