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. B

Karyotype: 2n = 54 and FN = 66. Autosomal complement: seven metacentric and submetacentric pairs (five large and two small), and 19 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a medium acrocentric; Y, a small subtelocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosome presented a pericentromeric heterochromatic block. 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. 7, Fig. 3 ).

The authors established maps of chromosomal homology between the karyotype of Neacomys sp. A and Neacomys sp. B by using whole chromosome probes of H. megacephalus . The comparative genomic mapping between the two Neacomys species shows that these karyotypes differs by the occurrence of 11 fusion/fission events, one translocation, four pericentric inversions, and four heterochromatic amplification events ( Silva et al. 2017).

Figures

FIGURE 3. Distribution of diploid and fundamental number of karyotyped specimens of genus Euryoryzomys. (■) E. emmonsae; (□) E. lamia; (▲) E. macconnelli; (○) E. nitidus; (l) E. russatus; (r) Euryoryzomys sp. nov.; (ê) Euryoryzomys sp..