Hylaeamys perenensis

Karyotype: 2n = 52 and FN = 62. Autosomal complement: six metacentric and submetacentric pairs medium to small decreasing in size, and 19 acrocentric pairs (one very large and the remaining large to small decreasing in size). Sex chromosomes: X, a large acrocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 6, Fig. 2C; Patton et al. 2000; Volobouev & Aniskin 2000). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes and on the X chromosome. The Y chromosome was entirely heterochromatic. G-banding was also performed (Volobouev & Aniskin 2000). A different fundamental number of 64 was reported by Musser et al. (1998, Malygin 1994 (congress abstract)).

The karyotype of H. oniscus and H. perenensis were very similar, however H. perenensis exhibits a distinctly large acrocentric chromosome that was not present in H. oniscus .