Neacomys, Thomas, 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 : 36

Neacomys sp. A

Karyotype: 2n = 58 and FN = 68. Autosomal complement: six metacentric and submetacentric pairs of medium size, and 22 acrocentric pairs (one large and the remaining medium to small decreasing in size). Sex chromosomes: X, a medium submetacentric; Y, a small submetacentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, three biarmed pairs presented a conspicuous heterochromatic block. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome was almost entirely heterochromatic. G-banding was also performed. FISH with telomeric sequences revealed signals exclusively at the ends of all chromosome arms and no interstitial signals were observed ( Silva et al. 2017, pp. 6, Fig. 2 ). According to the authors, this karyotype was similar to those described by Silva et al. (2015) for specimens identified as Neacomys sp. (2n = 58 / FN = 70, and 2n = 58 / FN = 64). The comparative analysis of C-banding revealed that the difference among the three karyotypes were due to blocks of heterochromatin affecting the number of chromosome arms ( Silva et al. 2017).

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.