Oecomys paricola Four different karyotypes were reported by Rosa et al. (2012) and Suárez-Villota et al. (2017), some of occurring sympatrically (Table 8, Fig. 13). Karyotype 1: 2n = 70 and FN = 72. Autosomal complement: two medium to small bi-armed pairs, and 32 acrocentric pairs large to small decreasing in size (Rosa et al. 2012, pp. 271, Fig. 6). Karyotype 2: 2n = 68 and FN = 72. Autosomal complement: three medium bi-armed pairs, and 30 acrocentric pairs large to small decreasing in size (Rosa et al. 2012, pp. 269, Fig. 2). Karyotype 3: 2n = 70 and FN = 76. Autosomal complement: four biarmed pairs medium to small decreasing in size, and 30 acrocentric pairs large to small decreasing in size (Rosa et al. 2012, pp. 270, Fig. 4; Suárez-Villota et al. 2017). Karyotype 4: 2n = 70 and FN = 74. Autosomal complement: three biarmed pairs medium to small decreasing in size, and 31 acrocentric pairs large to small decreasing in size (Suárez-Villota et al. 2017, pp. 12, Fig. 4D). Sex chromosomes: X chromosome presented two different morphologies, a large subtelocentric, and a large submetacentric; Y, a small submetacentric or a biarmed chromosome. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosome C-band vary from a heterochromatic block on the distal region of the short arm to present the short arm almost entirely heterochromatic. The Y chromosome was almost entirely or slightly heterochromatic (Rosa et al. 2012; Suárez-Villota et al. 2017). G-banding was also performed. The NORs stained vary from two to three acrocentric pairs of medium and/or small sized in the karyotypes 1–3, but were always localized at the telomeric regions of the short arms (Rosa et al. 2012). The differences in the diploid and fundamental number of the four karyotypes can be explained by rearrangements that include fusion/fission and pericentric inversions.

Published as part of 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, pp. 1-111 in Zootaxa 4876 (1) on page 55, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612