Cerradomys subflavus (Wagner, 1842)

Moreira, Camila Do Nascimento, Ventura, Karen, Percequillo, Alexandre Reis & Yonenaga-Yassuda, Yatiyo, 2020, A review on the cytogenetics of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae), with the description of new karyotypes, Zootaxa 4876 (1), pp. 1-111 : 9

Cerradomys subflavus

Karyotype: 2n = 54 and FN = 62. Autosomal complement: three large submetacentric pairs, two small metacentric pairs, and 21 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X chromosome presented two different morphologies, a large acrocentric (Xa), and a large subtelocentric (Xb); Y chromosome presented two different morphologies, a medium acrocentric (Ya), and a large acrocentric (Yb) ( Almeida & Yonenaga-Yassuda 1985, pp. 132, Fig. 2 ; Langguth & Bonvicino 2002). Two different morphologies of sex chromosomes were recognized by Percequillo et al. (2008), a medium acrocentric X and a small acrocentric Y. Variation in diploid (2n = 55 and 2n = 56) and fundamental number (FN = 63) were reported resulting from centric fusions affecting one large submetacentric pair ( Yonenaga et al. 1976; Almeida & Yonenaga-Yassuda 1985). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, with the exception of the three submetacentric pairs, in this case only a discrete staining was observed. The Xb exhibited constitutive heterochromatin on the short arm, on the centromeric and proximal region of long arm, and an interstitial C-band was observed on its long arm. The Ya presented a large heterochromatic block on the distal portion of its long arm, amounting to about two-thirds of its length, while no heterochromatin material was detected on the pericentromeric region. G- and Q-banding were also performed ( Almeida & Yonenaga-Yassuda 1985).

Another karyotype with 2n = 54 and FN = 64 was reported by Paresque et al. (2004) and Moreira et al. (2009). The difference in the fundamental number was due to the presence of one small metacentric pair instead of an acrocentric one. Moreira et al. (2009), presented another morphology for the Y chromosome, being a medium metacentric. These variations in diploid and fundamental number of C. subflavus occurs sympatrically on specimens collected in Bahia, Espírito Santo, Minas Gerais and São Paulo, states of Brazil ( Table 2, Fig. 2 ).

Figures

FIGURE 2. Distribution of diploid and fundamental number of karyotyped specimens of genus Cerradomys. (□) C. akroai; (■) C. goytaca; (ê) C. langguthi; (r) C. maracajuensis; (▲) C. marinhus; (○) C. scotti; (☆) C. subflavus; (l) C. vivoi.