The Distribution and biogeography of the cryptic multimammate mice, mastomys natalensis (A. Smith, 1834) and Mastomys coucha (A. Smith, 1836) in southern Africa

Abstract

Univariate and multivariate analyses were performed on 17 cranial and dental measurements taken from cytogenetically identified specimens of Mastomys natalensis and M coucha. Interpopulation and intrapopulation variation were investigated, and, craniometric discrimination technique for distinguishing between the two species was developed. This discrimination technique was used to identify specimens of M natalensis s. l. from the southern African and distributions of the two species were determined. Intrapopulation analyses indicated a lack of significant sexual dimorphism, but size related age variation was pronounced. Subsequent analyses of inter – population variation indicated a high degree of geographic variation in both species, with subtle but significant shape related differences between Zimbabwe samples and South African and Namibian samples. Interspecific analyses supported the existence of two shape- related morphometrically distinct taxa within M natalensis (sensu lato) in southern Africa, which are herein taxonomically equated to M natalensis and M coucha. Since geographic variation was substantial it was necessary to develop regionally based discrimination techniques. The distributions of the two species based on this revised data, shows that both species are broadly sympatric in southern Africa. The current data also shows positive correlation between rainfall data and the distribution of the two species, but lack thereof with altitude, vegetation or plague data.