Host-specificity and distribution of cephalochlamydid cestodes: correlation with allopolyploid evolution of pipid anuran hosts



The taxonomy and distribution of cephalochlamydid cestodes are reviewed. This group is primarily specific to pipid anurans and occurs naturally across sub-Saharan Africa. Paracephalochlamys gen. nov. has two large lateral testes (sometimes doubled or absent on one side) on the anterior margin of each segment, while Cephalochlamys Blanchard, 1908 has three to 23 small testes scattered in lateral fields. Paracephalochlamys papilionis sp. nov. infects Pseudhymenochirus merlini in Sierra Leone. The distribution of Cephalochlamys species is inferred from the previous literature and numerous new records. Cephalochlamys namaquensis (Cohn, 1906) occurs in Xenopus laevis laevis in Namibia, South Africa, Lesotho and Zimbabwe, X. l. poweri (new host record) in Zambia and the Democratic Republic of Congo (D.R.C.), X. l. victorianus in Kenya, Uganda, Rwanda and D.R.C., X. l. sudanensis (new host record) in Cameroon and Sudan, and the ranid anuran, Rana angolensis, in Zimbabwe. Anthropogenic dispersal of C. namaquensis, together with X. l. laevis, has occurred to localities in the south-western United States and Isle of Wight, U.K. Cephalochlamys compactus sp. nov., differentiated from C. namaquensis by a less well developed median ovarian cavity and more compact vitellarium, occurs in Xenopus muelleri in Togo, Ghana, Nigeria, Cameroon, D.R.C., Zimbabwe and South Africa, X. borealis in Kenya, X. clivii in Ethiopia, R. angolensis in Ethiopia and R. occipitalis in Nigeria. Cephalochlamys representatives of uncertain specific status have been recorded in X. gilli (new host record) in South Africa, X. pygmaeus and X. fraseri-like hosts (new host records) in the D.R.C., X. tropicalis (new host record) in Nigeria and R. occipitalis in Gabon. Despite the ability of some species to infect distantly related amphibians, the distribution of cephalochlamydid taxa amongst their principal hosts, pipids, can be related to the allopolyploid evolution of this anuran family.