Oligoryzomys, Bangs, 1900

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 : 77

Oligoryzomys sp.

Karyotype: 2n = 56 and FN = 58. Autosomal complement: two small metacentric pairs, and 25 acrocentric pairs (one large and the remaining medium to small decreasing in size). Sex chromosomes: X, a large submetacentric; Y, a large metacentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of the majority autosomal pairs. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome was entirely heterochromatic. NORs were localized on the short arm of one pair. FISH with telomeric sequences revealed signals exclusively at the ends of all chromosome arms and no interstitial signals were observed ( Andrades-Miranda et al. 2001a, pp. 1084, Fig. 2A ).

The genus Oligoryzomys exhibits 15 different diploid numbers, varying from 44 to 72, and 16 different fundamental numbers, varying from 52 to 82, one of the widest cytogenetic variations within the tribe. These species also present autosomal and sex chromosome polymorphisms, in addition to the presence of B chromosomes. Presently, there was no cytogenetic information for six known species of the genus, and two karyotypes were described for still unnamed species.

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.