A review on the cytogenetics of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae), with the description of new karyotypes Author Moreira, Camila Do Nascimento Author Ventura, Karen Author Percequillo, Alexandre Reis 0000-0001-9490-5457 cmoreirabio@gmail.com Author Yonenaga-Yassuda, Yatiyo text Zootaxa 2020 2020-11-06 4876 1 1 111 journal article 7983 10.11646/zootaxa.4876.1.1 4ee8b608-7c73-4980-9e86-3e3719e91c7f 1175-5326 4423612 190EC586-E14B-4AEF-A5EF-3DA401656159 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 .