Nephelomys caracolus

Karyotype: 2n = 66 and FN = 90. Autosomal complement: two medium subtelocentric pairs, 11 metacentric and submetacentric pairs medium to small decreasing in size, and 19 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a medium metacentric; Y, a small subtelocentric (Kiblisky 1969, pp. 1339, Fig. 1; Aguilera et al. 1995). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, some acrocentric pairs presented a lightly stained C-band on distal regions of its long arm. The X chromosome presented a conspicuous pericentromeric heterochromatic block. The Y chromosome was totally heterochromatic. G-banding was also performed (Aguilera et al. 1995).