Studies on the biology ofProtopolystoma xenopodis(Monogenoidea): the oncomiracidium and life-cycle

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Abstract
Protopolystoma xenopodis(Price, 1943) Bychowsky, 1957 is a parasite of the African clawed toads, species ofXenopus. Adult worms in the host's urinary bladder produce up to 15 eggs/24 h; these are voided with the urine and hatch after 20–24 days (at 26 °C). The swimming oncomiracidia enter the cloaca of the toad and travel via the urinary ducts to the kidneys. Larval development in the kidneys lasts 8–12 weeks (at 22 °C) and the juvenile parasites then migrate to the urinary bladder where maturity is reached after a further 3–4 weeks,i.e. 3–4 months after invasion. Egg production is continuous and parasite longevity has been found to exceed1½ years. Rarely, the adult worms may undertake a return migration from bladder to kidneys.The morphology of the oncomiracidium is described and compared with available accounts of other polystomatid genera. Consideration of data for the genusPolystomasuggests that the arrangement of the epidermal ciliary cells is relatively constant at the inter-specific level. Comparison ofProtopolystomawithPolystoma,DiplorchisandOculotremareveals that whilst the ciliary cell patterns are clearly related there are important differences in both cell number and disposition at the inter-generic level. Differences are also evident in the distribution of epidermal sensillae inProtopolystomaandPolystoma.Protopolystomais distinguished from all other polystomatids infecting anuran hosts by the presence of two pairs of haptoral hamuli.