Oligoryzomys rupestris (Weksler & Bonvicino, 2005)

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 : 75

Oligoryzomys rupestris

Karyotype: 2n = 46 and FN = 52. Autosomal complement: one small metacentric pair, one small submetacentric pair, two very large subtelocentric pairs, and 18 acrocentric pairs (one very large and 17 small). Sex chromosomes: X chromosome presented three different morphologies, a medium submetacentric, a medium subtelocentric, and a medium acrocentric; Y, a small acrocentric ( Silva & Yonenaga-Yassuda 1997; pp. 218, Fig. 2 ; Bonvicino et al. 2005; Weksler & Bonvicino 2005; Pereira & Geise 2007; Di-Nizo et al. 2015). Silva & Yonenaga-Yassuda (1997) reported another diploid number of 44 due to a centric fusion of the large acrocentric pair with one small acrocentric pair, and a mosaicism with 2n = 44/45 and FN = 52/53 due to the presence of a small acrocentric chromosome. These variations in diploid and fundamental number were reported only for specimens collected in Minas Gerais, state of Brazil ( Table 9, Fig. 17 ). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, with the exception of the subtelocentric pairs. The subtelocentric X presented a proximal heterochromatic block that extended to the short arm, the acrocentric X chromosome presented a large heterochromatic block on the proximal region and an interstitial lightly stained C-band on its long arm. The Y chromosome was entirely heterochromatic ( Silva & Yonenaga-Yassuda 1997). The G- and R-banding were also performed ( Silva & Yonenaga-Yassuda 1997; Di-Nizo et al. 2015). Multiple NORs, varying from two to twelve were localized at the telomeric regions of the short arms of acrocentric autosomes. FISH with telomeric sequences revealed signals exclusively at the ends of all chromosome arms and no interstitial signals were observed ( Silva & Yonenaga-Yassuda 1997).

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.

FIGURE 17. Distribution of diploid and fundamental number of karyotyped specimens of genus Oligoryzomys. (r) O. mattogrossae; (■) O. microtis; (○) O. moojeni; (☆) O. rupestris; (▲) O. stramineus; (l) O. utiaritensis.