The distribution of two medically and agriculturally important cryptic rodent species, Mastomys natalensis and M. coucha (Rodentia: Muridae) in South Africa

Abstract

The medically and agriculturally important Natal multimammate mouse, Mastomys natalensis (A. Smith, 1834) and the multimammate mouse, M. coucha (A. Smith, 1836), are sibling species and cannot easily be distinguished morphologically. As a consequence, their respective distributional ranges across South Africa remain uncertain. Consequently, locality data of positively identified (karyotyped and/or electrophoretically determined) specimens from South Africa were collated from museum records, the literature, and recently collected material in an attempt to: 1) delimit geographic distributions using positively identified specimens; 2) predict the most likely areas of occurrence of the two sibling species using a variety of selected eco geographic variables (EGVs) associated with verified locality data; and 3) assess both verified and predicted geographic distributions with reference to previously reported incidents of plague in South Africa. Both verified and predicted distributions are broadly similar and show a geographic separation along the eastern escarpment of South Africa that seems to be influenced by altitude and rainfall. M. natalensis occurs in the low altitude/high rainfall eastern coastal region, extending to northeastern South Africa, while M. coucha keeps to the high altitude/moderate rainfall central and northeastern South Africa. Although the two species were shown to be either sympatric or to occur in close proximity at four localities, additional research is needed to determine the zone of parapatry. Univariate and multivariate analyses showed statistically significant differences between eco geographic characteristics of collecting localities associated with each of the two species in South Africa. The derived distributions indicate previously reported cases of plague in South Africa, to some extent, coincide with the distributional range of M. coucha rather than M. natalensis.