Oecomys roberti (Thomas, 1904)

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 : 55

Oecomys roberti

There were three different karyotypes from different localities ( Table 8, Fig. 12 ). Karyotype 1: 2n = 80 and FN = 114. Autosomal complement: 15 metacentric and submetacentric pairs medium to small decreasing in size, three subtelocentric pairs of medium-sized, and 21 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a very large submetacentric (the largest chromosome of the complement); Y, a very small acrocentric ( Patton et al. 2000, pp. 130, Fig. 90). Karyotype 2: 2n = 82 and FN = 106. Autosomal complement: 13 metacentric and submetacentric pairs medium to small decreasing in size, and 27 acrocentric pairs large to medium decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a small acrocentric ( Langguth et al. 2005, pp. 188, Fig. 2 ; Suárez-Villota et al. 2017). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosome presented the short arm entirely heterochrmatic. The Y chromosome was slightly heterochromatic ( Suárez-Villota et al. 2017). Karyotype 3: 2n = 82 and FN = 110. Autosomal complement: 15 biarmed pairs medium to small decreasing in size, and 25 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a medium acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of the majority of autosomal pairs. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome was almost entirely heterochromatic. Multiple NORs, were localized at the telomeric regions of the short arms of 1–2 medium to small acrocentric pairs ( Andrades-Miranda et al. 2001b, pp. 272, Fig. 2C ).

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 12. Distribution of diploid and fundamental number of karyotyped specimens of genus Oecomys. (▲) O. auyantepui; (○) O. bicolor; (□) O. cleberi; (■) O. franciscorum; (ê) O. roberti; (l) Oecomys sp. 1; (r) Oecomys sp. 2.