Nephelomys keaysi

Karyotype: 2n = 80 and FN = 92. Autosomal complement: seven medium to small metacentric and submetacentric pairs, and 32 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a very large subtelocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 4, Fig. 1C).