Euryoryzomys lamia (Thomas, 1901)

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 : 14

Euryoryzomys lamia

Karyotype: 2n = 58 and FN = 84. Autosomal complement: 14 biarmed pairs large to small decreasing in size, and 14 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a medium subtelocentric; Y, a submetacentric. G-banding was also performed (Bonvicino et al. 1998, pp. 254, Fig. 1 ; Bonvicino et al. 2005).

The same karyotype and two different cytotypes for this species were reported by Andrades-Miranda et al. (2000) for specimens from Goiás, Brazil. Cytotype 1: 2n = 64 and FN = 84. Autosomal complement: 11 biarmed pairs large to small decreasing in size, and 20 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a large subtelocentric; Y, unknown as only as two females were analyzed. Cytotype 2: 2n = 60 and FN = 84. Autosomal complement: 13 biarmed pairs large to small decreasing in size, and 16 acrocentric pairs (one large and the remaining small). Sex chromosomes: X, a large subtelocentric; Y, unknown as only a female was analyzed. C-banding metaphases exhibited pericentromeric constitutive heterochromatic blocks on all autosomes and on the X chromosomes (Andrade-Miranda et al. 2000, pp. 466, 3B and C). According to the authors, the two different cytotypes reported differs in that presented by Bonvicino et al. (1998), because they present karyotypes with six additional (cytotype 1) and two extra (cytotype 2) pairs of small acrocentric and less three pairs and one pair of biarmed chromosomes, respectively. This decrease of the number of acrocentric pairs suggests that Robertsonian rearrangement could differentiate the three cytotypes of E. lamia ( Andrades-Miranda et al. 2000) . The first karyotype described for this species (2n = 58 and FN = 84) was reported only for specimens collected in the northern region of Goiás, states of Brazil ( Table 3, Fig. 3 ), whereas the cytotype 1 (2n = 64 and FN = 84) and cytotype 2 (2n = 60 and FN = 84) occur sympatrically in the southern region of this same state ( Table 3, Fig. 3 ).

Figures

FIGURE 1. Collection localities of Oryzomyini species analyzed in this work. (1) Claúdia, Mato Grosso state; (2) and (3) Rio Japurá, Amazonas state; (4) and (5) Rio Içá, Amazonas state.

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..