Polystomatidae (Monogenea) of southern African Anura: polystoma channingi n.sp. parasitic in two closely related cacosternum species

Abstract

Polystoma channingi is described as a new species of the polystomatid flatworm (Monogenea) parasitic in the urinary bladder of Cacosternum nanum in the Eastern Cape Province, South Africa. In localities where C. nanum and C. boettgeri occur sympatrically the parasite may be found in both species. This finding of a Polystoma in two closely related host species questions the strict host-specificity generally ascribed to the genus but supports the hypothesis that host-specificity is determined by the oncomiracidium’s ability to recognise the tadpole as a suitable host. This is the first polystome to be described from Cacosternum and the ninth species of Polystoma from South Africa. The species is distinguished by its huge haptor and suckers relative to the body size. The haptor length / body length ratio of 0.38 is by far the largest for the known Southern African polystomes. For C. boettgeri the prevalence was 28.6% and for C. nanum 25% while the mean intensity for infections of adult frogs were 1.5 for C. boettgeri and 1.0 for C. nanum