Oecomys roberti

There were three different karyotypes from different localities (Table 8, Fig. 12). Karyotype 1: 2n = 80 and FN = 114. Autosomal complement: 15 metacentric and submetacentric pairs medium to small decreasing in size, three subtelocentric pairs of medium-sized, and 21 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a very large submetacentric (the largest chromosome of the complement); Y, a very small acrocentric (Patton et al. 2000, pp. 130, Fig. 90). Karyotype 2: 2n = 82 and FN = 106. Autosomal complement: 13 metacentric and submetacentric pairs medium to small decreasing in size, and 27 acrocentric pairs large to medium decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a small acrocentric (Langguth et al. 2005, pp. 188, Fig. 2; Suárez-Villota et al. 2017). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosome presented the short arm entirely heterochrmatic. The Y chromosome was slightly heterochromatic (Suárez-Villota et al. 2017). Karyotype 3: 2n = 82 and FN = 110. Autosomal complement: 15 biarmed pairs medium to small decreasing in size, and 25 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a medium acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of the majority of autosomal pairs. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome was almost entirely heterochromatic. Multiple NORs, were localized at the telomeric regions of the short arms of 1–2 medium to small acrocentric pairs (Andrades-Miranda et al. 2001b, pp. 272, Fig. 2C).