Polystoma australis (Monogenea): Life cycle studies in experimental and natural infections of normal and substitute hosts



A South African polystome parasite found in Kassina senegalensis (Dumeril & Bibron, 1841) was thought to be different from Polystoma australis Kok & van Wyk, 1986, which occurs in K. wealii Boulenger, 1882. The successful establishment and development of parasites, following experimental cross-infestations, indicated that both Kassina spp. are infected only by P. australis. Observations on naturally infected hosts showed a comparable prevalence of P. australis in larval populations of the two host species. Experimental cross-infestations also led to the establishment of branchial and vesical P. australis in larval and post-metamorphic Natalobatrachus bonebergi Hewitt & Methuen, 1913. Field observations showed the presence of branchial P. australis in tadpoles of Rana angolensis Bocage, 1866, occurring together with heavily infected K. wealii tadpoles. The findings are relevant to aspects of the taxonomy and host-specificity of the African anuran polystomes.


  • 1Polystoma australis, a parasite of Kassina wealii, was established experimentally in larval and post-metamorphic K. senegalensis. The results indicated normal host-parasite compatibility and it was concluded that natural infections of K. senegalensis also involve P. australis.
  • 2When tadpoles of the two host species occupied the same pools, the prevalence of P. australis in both populations was comparable. When K. senegalensis occurred alone, P. australis was absent. This gives the impression of host preference but may be due to differences in the population density of the two host species.
  • 3Data are given on the establishment, migration and mortality of branchial parasites developing towards neotenic maturity in the normal host. Migration from the left to the right branchial chamber occurs within the first eight days. Since parasite mortality is continuous, there is a great loss of reproductive potential.
  • 4Polystoma australis was established experimentally in larval and post-metamorphic Natalobatrachus bonebergi. Rana angolensis tadpoles were found to be naturally infected with predestined bladder stages of P. australis. These findings emphasize the complexity of host-parasite associations within the African anuran polystomes.