Holochilus vulpinus (Brants, 1827)

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 : 20

Holochilus vulpinus

Karyotype: 2n = 36 and FN = 56. Autosomal complement: 11 metacentric and submetacentric pairs large to small decreasing in size, and six small acrocentric pairs. Sex chromosomes: X, a large acrocentric; Y, a small acrocentric. The acrocentric short arm was frequently visible on the X chromosome, but not on the Y. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosome presented constitutive heterochromatin on the pericentromeric region, while the Y chromosome was largely heterochromatic. G-banding was also performed. Furthermore, one to three supernumerary chromosomes were reported. All B chromosomes were small acrocentric, and largely heterochromatic. The authors reported an addition of euchromatin to the short arm of one X chromosome in a single female, plus one female with only one X chromosome ( Nachman 1992a, pp. 13, Fig. 4 ). In the original report Nachman (1992a) considered the fundamental number as the number of all chromosome arms, including sex and B chromosomes. Here the fundamental number was given as the number autosomal arms, excluding sex and supernumerary chromosomes. Riva et al. (1977) reported a karyotype variability of 2n = 36, 37 and FN = 56, 57 for samples from northern Argentina. These karyotypes seem to belong to H. vulpinus , because this variability of diploid and fundamental number was described only for H. vulpinus species, and because of the collection locality.

Figures

FIGURE 4. Karyotype of Euryoryzomys sp., male with 2n = 58 and FN = 92. (A) Conventional staining (JAP 228); (B) C-banding (JAP 228); (C) G-banding (JAP 228); (D) Metaphase plate after fluorescent in situ hybridization with telomeric probe (left) and DAPI staining (right) (JAP 228), arrows indicate the hybridization of interstitial telomeric sequence.