Polystoma vernoni n. sp. (Monogenea: Polystomatidae) from the sharp nosed grass frog Ptychadena oxyrhynchus (Smith, 1849) in South Africa.

Polystoma vernoni (Polystomatidae) is a new species in the urinary bladder of Ptychadena oxyrhynchus in KwaZulu-Natal province, South Africa. Ptychadena is a true African species and the 49 currently known species in Africa harbour 11 polystome parasites. Ptychadena oxyrhynchus has an extensive distribution through Africa and harbours Polystoma prudhoei in West Africa. This new parasite differs significantly from P. prudhoei. The new species is distinguished by its long body relative to its haptor length, its unique shape and its ratio of marginal hooklets. In a sample of 13 frogs, 53.8% were infected with up to 18 parasites per host (mean intensity 4.86).