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 Cerradomys scotti Karyotype: 2n = 58 and FN = 70. Autosomal complement: seven small metacentric and submetacentric pairs, and 21 acrocentric pairs large to small decreasing in size. Sex chromosomes: X chromosome presented three different morphologies, a large submetacentric (Xa), a large subtelocentric (Xb), and a large subtelocentric shorter than Xb (Xc); Y chromosome presented three different morphologies, a medium submetacentric (Ya), a medium subtelocentric (Yb), and a medium acrocentric (Yc). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosomes presented their short arms and centromeric regions heterochromatic, besides two interstitial bands on its long arms. The three types of Y chromosomes presented their long arms almost entirely heterochromatic. G- and R-banding were also performed. Multiple NORs, varying from three to eleven, were localized on the short arms of acrocentric autosomes ( Svartman & Almeida 1992a , pp. 317, Fig. 1 ). FISH with telomeric sequences revealed signals exclusively at the ends of all chromosome arms and no interstitial signals were observed ( Andrades-Miranda et al . 2002 ). The same diploid number was reported by Bonvicino et al . (1999) , Langguth & Bonvicino (2002) and Bonvicino et al . (2005) . These authors reported a different fundamental number of 72 due to a presence of one medium subtelocentric pair instead of a medium acrocentric one, and two males carrying one additional B chromosome. These variation in fundamental number occurs sympatrically on specimens collected in Goiás , state of Brazil ( Table 2 , Fig. 2 ).