Isozyme and allozyme markers distinguishing two morphologically similar, medically important Mastomys species (Rodentia: Muridae)

Fifteen proteins or enzymes provided interpretable results at a total of 39 loci. Additional fixed allele differences between the species were detected at AAT-1, ADH, EST-1, PGD-1, Hb-1 and -2. Average heterozygosities for M. coucha and M. natalensis were calculated as 0.018 and 0.032 respectively, with a mean genetic distance between the species of 0.26.The confirmation of the isozyme and the detection of the additional allozyme markers are important contributions to the identification of these two medical and agricultural pest species.The Praomys/Mastomys species complex is a group of morphologically similar species that occur in very diverse habitats throughout sub-Saharan Africa [1]. The taxonomy of this group has been clouded by a diversity of opinions and this confusion has been further compounded by many external and cranial similarities between species, and thus the systematics of this group remains poorly understood, with many species yet to be described [1]. The genus Mastomys is well represented in southern Africa, especially by the ubiquitous multimammate mice, Mastomys coucha (Smith, 1836) and M. natalensis (Smith, 1834). The distribution of both species is only provisional at this stage [2], and the species are known to be sympatric in some areas, and allopatric in others. These common agricultural pests are also commensal with man, often sheltering in houses in order to safely rear their young. In African kraals they occur in very large numbers, living in the fabric and thatch of pole and mud huts [2].Because these mice carry important diseases, the medical implications of this cohabitation with man are obvious. Mastomys coucha acts as a reservoir for the Rickettsian Yersinia pestis, the organism causing plague [3]. The three forms of plague are bubonic, primary pneumonic and primary septicaemic. Bubonic plague, which is the most common type in epidemics, is fatal in about 25% to 50% of untreated cases. Pneumonic plague, a highly contagious (airborne)