Problems presented by geographical variation in the African vine snakes, genus Thelotornis

Abstract

Analysis of variation in 771 specimens of the genus Thelotornis A. Smith (Colubridae) confirms the absence of intergradation between the taxa kirtlandii (Hallowell) and oatesii (Gunther) in northern Angola and southern Zaire, so 7. capensis A. Smith is accepted as a full species. The western race 7. capensis oatesii shows very little variation, but the eastern populations of 7. capensis are extremely variable and it is convenient to revive the name mossambicanus (Bocage) for the populations which occur from central Mocambique northwards. T. c. oatesii hybridizes extensively with T. c. capensis and 7. c. mossambicanus in southeastern Rhodesia and adjacent Mocambique. Northern populations of 7. c. mossambicanus show features of 7. kirtlandii, but these are apparently primitive characters retained since the original partition of Thelotornis into western and eastern forms. The highlands of Kenya and northern Tanzania isolate these northern mossambicanus from the nearest kirtlandii populations in Uganda.