The biology and systematics of a new species of Xenopus (Anura: Pipidae) from the highlands of Central Africa

A new species of clawed toad, Xenopus wittei sp. nov. is described from highland areas overlapping the borders of Rwanda, Uganda and Zaire. A comprehensive morphological analysis of the species has been carried out. X. wittei sp. nov. is very closely related to X. vestitus and both have a tetraploid chromosome complement (2 n = 72), the only examples within the genus. Nevertheless, the two species may be distinguished by easily observed features, including head morphology and dorsal body colours and patterns, and are also identified by their karyotypes and mating calls.
Data on distribution, ecology and parasite infection are derived from both museum collections and fieldwork in Central Africa. X. wittei sp. nov. is sympatric in parts of its range with X. vestitus, X. laevis victorianus and X. I. bunyoniensis , with up to three of the taxa sharing the same habitats. The implications of potential species interactions are discussed. Experimental hybridization has confirmed the reproductive isolation of the two tetraploid species. Parasitological studies show that they may be distinguished from one another by host specific species of the nematode Chitwoodchabaudia and from other Xenopus species by the absence of the tapeworm genus Cephalochlamys . Large scale population movements of the Xenopus species have apparently occurred in the Central African highlands during the period of available records. Sympatry observed amongst the present day representatives of Xenopus may have been an important factor in the evolution of these toads since X. wittei sp. nov. and X. vestitus are interpreted as allopolyploids, the products of interspecies hybridization.