“…Within the taxonomic group Mastomys natalensis (Smith, 1834) sensu latu (syn. Mastomys coucha Smith, 1834) an extreme degree of karyotype variability has been described with diploid numbers of 2n = 38, 36 and 32 (MATTHEY, 1954(MATTHEY, , 1955(MATTHEY, , 1958(MATTHEY, , 1965(MATTHEY, , 1966a(MATTHEY, , 1966b(MATTHEY, , 1967(MATTHEY, , 1970FoRD & HAMERTON, 1956;HuANG & STRONG, 1962;KRAL, 1971;LYONS et al, 1977;HALLETT, 1979;LEE & MARTIN, 1980). Nevertheless, MATTHEY (1955) thought that the 32 chromosome Mastomys specimens found at Oubangi (Central African Republic) belonged to a species different from Mastomys natalensis.…”