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 Holochilus brasiliensis Karyotype: 2n = 40 and FN = 56. Autosomal complement: eight biarmed pairs large to small decreasing in size, one small metacentric pair, and 10 small acrocentric pairs. Sex chromosomes: X, a medium acrocentric; Y, a small acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of eight acrocentric pairs, and two biarmed pairs. The X chromosome presented constitutive heterochromatin on the centromeric region and on the short arm, while the Y chromosome presented a distal half heterochromatic region. G-banding was also performed ( Freitas et al . 1983 , pp. 16, Fig. 4 ).