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Zygodontomys sp. 1 Karyotype: 2n = 84 and FN = 96 to 98. Autosomal complement: two large submetacentric and subtelocentric pairs, four or five medium to small biarmed pairs, and the remaining being acrocentric. Sex chromosomes: X, a large submetacentric; Y, a medium subtelocentric. G-banding was also performed (Mattevi et al. 2002; Bonvicino et al. 2009).

Sigmodontomys Allen 1897 Monotypic genus represented by S. alfari (Allen 1897), found throughout trans-Andean lowland and lower montane forests in Colombia, Venezuela, and Ecuador, besides Central American lowland forests from Panamá to Honduras (Pine et al. 2012; Prado & Percequillo 2013; Weksler 2015b). Karyotype: 2n = 56 and FN = 54. Autosomal complement: 27 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large-medium acrocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 13, Fig. 6A)., 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 78, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Pine, R. H., Timm, R. M. & Weksler, M. (2012) A newly recognized clade of trans-Andean Oryzomyini (Rodentia, Cricetidae), with description of a new genus. Journal of Mammalogy, 93 (3), 851 - 870. https: // doi. org / 10.1644 / 11 - MAMM-A- 012.1","Prado, J. R. & Percequillo, A. R. (2013) Geographic distribution of the genera of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae) in South America: patterns of distribution and diversity. Archivos de Zoologia, 44 (1), 1 - 120. https: // doi. org / 10.11606 / issn. 2176 - 7793. v 44 i 1 p 1 - 120","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48."]}

Holochilus chacarius Karyotype: 2n = 48 and FN = 56. Autosomal complement: five metacentric pairs (four large and one small), and 18 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a medium acrocentric; Y, a small acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, with the exception of one large metacentric pair. The X chromosome presented pericentromeric heterochromatic blocks, the Y chromosome was almost entirely heterochromatic. G-banding was also performed (Nachman & Myers 1989, pp 6668, Fig. 1A). The karyotype of H. chacarius was highly variable, with diploid number ranging from 48 to 55, and fundamental number from 56 to 60. This variation occurs within and between populations from Paraguay and Argentina (Table 4, Fig. 5), and was resulted from multiple Robertsonian translocations (Nachman & Myers 1989; Nachman 1992a). Furthermore, two different types of supernumerary chromosome were reported: B1 was a small to large metacentric or submetacentric chromosome that contains only centromeric heterochromatin, and B2 was a small acrocentric chromosome that was largely heterochromatic. The authors reported a pericentromeric inversion of a single X chromosome in one female, terminal euchromatic addition to the short arm of the X chromosome in nine specimens, euchromatic addition adjacent to the pericentromeric region in one autosomal pair of two specimens, and one female with only one X chromosome (Nachman & Myers 1989; Nachman 1992a). In the original report, Nachman & Myers (1989), and latter 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 of autosomal arms, excluding sex and supernumerary chromosomes. A karyotype with 2n = 48 and FN = 60, was reported by Gardner & Patton (1976) for a sample from Paraguay, however this specimen presented a submetacentric X chromosome, that accounts for the difference from the former karyotype. Vidal et al. (1976) reported a karyotype variation for genus Holochilus, 2n = 50–54 and FN = 56–60, for samples from Argentina that seems to belong to H. chacarius. We assumed this correlation, as this variability of diploid and fundamental number was described only for H. chacarius, and due to the proximity of collection localities., 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 pages 18-19, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Nachman, M. W. & Myers, P. (1989) Exceptional chromosomal mutations in a rodent population are not strongly underdominant. Proceedings of the National Academy of Sciences, 86, 6666 - 6670. https: // doi. org / 10.1073 / pnas. 86.17.6666","Nachman, M. W. (1992 a) Geographic patterns of chromosomal variation in South American marsh rats, Holochilus brasiliensis and H. vulpinus. Cytogenetics and Cell Genetics, 61, 10 - 16. https: // doi. org / 10.1159 / 000133361","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48.","Vidal, O. R., Riva, R. & Baro, N. I. (1976) Los cromosomas del genero Holochilus. I. Polimorfismo en H. chacarius Thomas (1906). Physis, 35, 75 - 85."]}

Nephelomys pectoralis Karyotype: 2n = 66 and FN = 94. Autosomal complement: nine medium to small metacentric and submetacentric pairs, six subtelocentric pairs (three large and three small), and 17 acrocentric pairs (one large and the remaining medium to small). Sex chromosomes: X, a large acrocentric; Y, a small submetacentric (Gardner & Patton 1976, pp. 4, Fig. 1B)., 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 47, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48."]}

Oecomys rutilus Karyotype: 2n = 54 and FN = 90. Autosomal complement: 12 metacentric pairs large to small decreasing in size, three submetacentric pairs (two medium and one small), four subtelocentric pairs large to medium-sized, and seven acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a medium subtelocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin, ranging from subtle to conspicuous, on the pericentromeric region of some chromosomal pairs. G-banding was also performed. NORs were localized at the telomeric regions of the short arms of one large and one small autosomal pair. FISH with 18S rDNA revealed signals at the telomeric regions of the short arms of one large and one small autosomal pair, while FISH with 5S rDNA revealed signals at the pericentromeric region of one large autosomal pair. FISH with telomeric sequences revealed signals exclusively at the ends of all chromosome arms and no interstitial signals were observed (Gomes-Júnior et al. 2016, pp. 412, Fig. 5)., 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 56, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gomes-Junior, R. G., Schneider, C. H., Lira, T., Carvalho, N. D. M., Feldberg, E., Silva, M. N. F. & Gross, M. C. (2016) Intense genomic reorganization in the genus Oecomys (Rodentia, Sigmodontinae): comparison between DNA barcoding and mapping of repetitive elements in three species of the Brazilian Amazon. Comparative cytogenetics, 10 (3), 401 - 426. https: // doi. org / 10.3897 / compcytogen. v 10 i 3.8306"]}

Oecomys cleberi There were three different karyotypes for this species that occur in different localities (Table 8, Fig. 12). Karyotype 1: 2n = 80 and FN = 140. Autosomal complement: 31 metacentric and submetacentric pairs, and eight acrocentric pairs. Sex chromosomes: X, a large submetacentric; Y, an acrocentric. C-banding was performed, the X chromosome presented the short arm entirely heterochrmatic and the Y chromosome was entirely heterochromatic (Suárez-Villota et al. 2017, pp. 12, Fig. 4B). Karyotype 2: 2n = 80 and FN = 134. Autosomal complement: 28 biarmed pairs, and 11 acrocentric pairs. Sex chromosomes: X, a large submetacentric; Y, a medium acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome presented an heterochromatic block on the distal region of the long arm (Suárez-Villota et al. 2017, pp. 12, Fig. 4C). Karyotype 3: 2n = 80 and FN = 124. Autosomal complement: one large subtelocentric pair, 22 biarmed pairs medium to small decreasing in size, and 16 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a medium acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of the majority of autosomal pairs. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome was almost entirely heterochromatic. Multiple NORs, were localized at the telomeric regions of the short arms of 1-2 medium-small acrocentric pairs (Andrades-Miranda et al. 2001b, pp. 272, Fig. 2B)., 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 54, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Suarez-Villota, E. Y., Carmignotto, A. P., Brandao, M. V., Percequillo, A. R. & Silva, M. J. J. (2017) Systematics of the genus Oecomys (Sigmodontinae: Oryzomyini): molecular phylogenetic, cytogenetic and morphological approaches reveal cryptic species. Zoological Journal of the Linnean Society, zlx 095, 1 - 29. https: // doi. org / 10.1093 / zoolinnean / zlx 095","Andrades-Miranda, J., Oliveira, L. F. B., Zanchin, N. I. T. & Mattevi, M. S. (2001 b) Chromosomal description of the rodent genera Oecomys and Nectomys from Brazil. Acta Theriologica, 46 (3), 269 - 278. https: // doi. org / 10.1007 / BF 03192433"]}

Microakodontomys Hershkovitz 1993 Monotypic genus represented by M. transitorius (Hershkovitz 1993), that inhabits the fringe zone between open grassland and bordering scrubland of the Brazilian Cerrado (Hershkovitz 1993; Prado & Percequillo 2013; Paresque & Hanson 2015). Karyotype: 2n = 38 and FN = 46. Autosomal complement: five small pairs of biarmed elements, and 13 acrocentric pairs decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a small submetacentric, as mentioned by Paresque & Hanson (2015)., 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 pages 29-30, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Hershkovitz, P. (1993) A new central brazilian genus and species of Sigmodontine rodent (Sigmodontinae) transitional between akodonts and oryzomyines, with a discussion of Muroid molar morphology and evolution. Fieldiana Zoology, 75, 1 - 18. https: // doi. org / 10.5962 / bhl. title. 3370","Prado, J. R. & Percequillo, A. R. (2013) Geographic distribution of the genera of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae) in South America: patterns of distribution and diversity. Archivos de Zoologia, 44 (1), 1 - 120. https: // doi. org / 10.11606 / issn. 2176 - 7793. v 44 i 1 p 1 - 120","Paresque, R. & Hanson, J. D. (2015) Genus Microakodontomys Hershkovitz, 1993. In: Patton, J., Pardinas, U. F. J. & D'Elia, G. (Eds.), Mammals of South America. 2. Rodents. University of Chicago Press, Chicago, Illinois, pp. 354 - 355."]}

Nephelomys caracolus Karyotype: 2n = 66 and FN = 90. Autosomal complement: two medium subtelocentric pairs, 11 metacentric and submetacentric pairs medium to small decreasing in size, and 19 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a medium metacentric; Y, a small subtelocentric (Kiblisky 1969, pp. 1339, Fig. 1; Aguilera et al. 1995). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, some acrocentric pairs presented a lightly stained C-band on distal regions of its long arm. The X chromosome presented a conspicuous pericentromeric heterochromatic block. The Y chromosome was totally heterochromatic. G-banding was also performed (Aguilera et al. 1995)., 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 46, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Kiblisky, P. (1969) The chromosomes of two species of the genus Oryzomys (Rodentia-Cricetidae). Experientia, 25 (12), 1338 - 1339. https: // doi. org / 10.1007 / BF 01897538","Aguilera, M., Perez-Zapata, A. & Martino, A. (1995) Cytogenetics and karyosystematics of Oryzomys albigularis (Rodentia, Cricetidae) from Venezuela. Cytogenetics and cell genetics, 69, 44 - 49. https: // doi. org / 10.1159 / 000133935"]}

Drymoreomys Percequillo, Weksler & Costa 2011 Monotypic genus represented by D. albimaculatus (Percequillo, Weksler & Costa 2011), all known specimens were from the eastern slopes of the Serra do Mar, in the coastal Brazilian Atlantic Rainforest from Rio de Janeiro to Santa Catarina states (Percequillo et al. 2011; Delciellos et al. 2015). Karyotype: 2n = 62 and FN = 62. Autosomal complement: one small metacentric pair, and 29 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a large submetacentric slightly smaller than the X (Suárez-Villota et al. 2013, pp. 68, Fig. 1; Delciellos et al. 2015). C-banding metaphases exhibited pericentromeric constitutive heterochromatic blocks on all autosomes and on the long arm of Y. G-banding was also performed. FISH with telomeric sequences revealed signals at the ends of all chromosomes, and additional telomeric sequences were found on the pericentromeric region of both X and Y chromosomes (Suárez-Villota et al. 2013).

Neacomys sp. Cytotype 1: 2n = 58 and FN = 70. Autosomal complement: seven medium metacentric and submetacentric pairs, and 21 acrocentric pairs. 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, on two biarmed pairs the heterochromatic blocks were bigger, and other three biarmed were almost heterochromatic. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome was almost entirely heterochromatic (Silva et al. 2015, pp. 4, Fig. B1; Silva et al. 2019). Cytotype 2: 2n = 58 and FN = 64. Autosomal complement: four small metacentric pairs, and 24 acrocentric pairs. 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, and three biarmed pairs were almostly heterochromatic. The X chromosome presented the short arm entirely heterochromatic. The Y chromosome was almost entirely heterochromatic (Silva et al. 2015, pp. 4, Fig. B2). These two cytotypes occurs in different localities of Pará, state of Brazil (Silva et al. 2015; Silva et al. 2019). G-banding was also performed. FISH with 18s rDNA sequences revealed signals of NORs on the distal region of the long arm of three autosomal pairs, one metacentric and two small acrocentric pairs of both cytotypes. FISH with telomeric sequences revealed signals exclusively at the ends of all chromosome arms and no interstitial signals were observed in either cytotypes (Silva et al. 2015). Silva et al. (2019) established maps of chromosomal homology between cytotype 1, and cytotype 2 of Neacomys sp., by using whole chromosome probes of H. megacephalus. The comparative genomic mapping showed that these cytotypes differs by the presence of blocks of constitutive heterochromatin on the short arms of metacentric chromosomes 22, 23, and 26 of cytotype 1, that was absent on acrocentric chromosomes 22, 24, and 23 of cytotype 2. Di-Nizo et al. (2017) also reported a diploid number of 58 for a Neacomys species from Mato Grosso, state of Brazil, with a different fundamental number of 66 (Di-Nizo et al. 2017, pp. 859, Fig. 1)., 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 34, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Silva, W. O., Pieczarka, J. C., Rossi, R. V., Schneider, H., Sampaio, I., Miranda, C. L., Silva, C. R., Cardoso, E. M. & Nagamachi, C. Y. (2015) Diversity and karyotypic evolution in the genus Neacomys (Rodentia, Sigmodontinae). Cytogenetic and Genome Research, 146 (4), 296 - 305. https: // doi. org / 10.1159 / 000441173","Silva, W. O., Pieczarka, J. C., Costa, M. J. R., Ferguson-Smith, M. A., O'Brien, P. C. M., Mendes-Oliveira, A. C., Rossi, R. V. & Nagamachi, C. Y. (2019) Chromosomal phylogeny and comparative chromosome painting among Neacomys species (Rodentia, Sigmodontinae) from eastern Amazonia. BMC evolutionary biology, 19 (1), 184. https: // doi. org / 10.1186 / s 12862 - 019 - 1515 - z","Di-Nizo, C. B., Banci, K. R. S., Sato-Kuwabara, Y. & Silva, M. J. J. (2017) Advances in cytogenetics of Brazilian rodents: cytotaxonomy, chromosome evolution and new karyotypic data. Comparative cytogenetics, 11 (4), 833 - 892. https: // doi. org / 10.3897 / compcytogen. v 11 i 4.19925"]}

Oligoryzomys andinus Karyotype: 2n = 60 and FN = 70. Autosomal complement: six metacentric and submetacentric pairs (two large, one medium and three small), and 23 acrocentric pairs (one large and the remaining small). Sex chromosomes: X was a large acrocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 8, Fig. 3E)., 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 60, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48."]}

Neacomys guianae Karyotype: 2n = 56, the G-banding karyotype was performed by Baker et al. (1983)., 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 33, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Baker, R. J., Koop, B. F. & Haiduk, M. W. (1983) Resolving systematic relationships with G-bands: a study of five genera of South American Cricetine rodents. Systematic zoology, 32 (4), 403 - 416. https: // doi. org / 10.2307 / 2413167"]}

Microryzomys Thomas 1917 The genus Microryzomys comprises two species, M. altissimus (Osgood 1933), and M. minutus (Tomes 1860). These species were endemic to the northern and central Andes, from northern Venezuela, through Colombia, Ecuador and Peru, to central Bolivia (Carleton & Musser 1989; Carleton 2015)., 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 30, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Carleton, M. D. & Musser, G. G. (1989) Systematic studies of oryzomyine rodents (Muridae, Sigmodontinae): a synopsis of Microryzomys. Bulletin of the American Museum of Natural History, 191, 1 - 83."]}

Nephelomys levipes Karyotype: 2n = 76 and FN = 88, mentioned by Percequillo (2015e) based on information provided by J. L. Patton., 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 46, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Percequillo, A. R. (2015 e) Genus Nephelomys Weksler, Percequillo, & Voss, 2006. In: Patton, J., Pardinas, U. F. J. & D'Elia, G. (Eds.), Mammals of South America. 2. Rodents. University of Chicago Press, Chicago, Illinois, pp. 377 - 390."]}

Transandinomys Weksler, Percequillo & Voss 2006 The genus Transandinomys comprises two species, T. bolivaris (Allen 1901), and T. talamacae (Allen 1891). Both occur in tropical lowland and premontane trans-Andean rain forests from north-eastern Nicaragua throughout much of Costa Rica and Panama to Colombia, western Ecuador, and northern Venezuela (Musser et al. 1998; Weksler et al. 2006). All cytogenetic data available for the genus was presented on Table 10. The distribution of diploid and fundamental number of karyotyped specimens were presented on Fig. 21., 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 80, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Weksler, M., Percequillo, A. R. & Voss, R. S. (2006) Ten new genera of oryzomyine rodents (Cricetidae: Sigmodontinae). Bulletin of the American Museum of Natural History, 3537, 1 - 29.","Musser, G. G., Carleton, M. D., Brothers, E. M. & Gardner, A. L. (1998) Systematic studies of Oryzomyine rodents (Muridae, Sigmodontinae): diagnoses and distributions of species formerly assigned to Oryzomys \" capito \". Bulletin of the American Museum of Natural History, 236, 1 - 376."]}

Oligoryzomys delicatus Karyotype: 2n = 60 and FN = 72. Autosomal complement: seven metacentric and submetacentric pairs medium to small decreasing in size, and 22 acrocentric pairs (three large and the remaining small). Sex chromosomes: X, a medium acrocentric; Y, a small acrocentric (Kiblisky 1969, pp. 1339, Fig. 3). Another karyotype with a different diploid and fundamental number was reported by Gardner & Patton (1976), 2n = 62 and FN = 74 or 76 (fundamental number comprises autosomal and sex chromosomes). Chromosome complement: five metacentric pairs (one large and four small), three subtelocentric pairs large to small decreasing in size, and 23 acrocentric pairs (one very large and the remaining small), the sex chromosome of this karyotype was unknown as only a female was examined. Baker et al. (1983) reported a diploid number of 60 and 64 for O. delicatus, and presented the G-banding for these karyotypes. These variation in diploid and fundamental number of O. delicatus occurs in different localities of Suriname and Venezuela (Table 9). This karyotype was originally attributed to O. longicaudatus, variant 3, by Gardner & Patton (1976), but Weksler & Bonvicino (2015b) assigned it to O. delicatus., 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 60, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Kiblisky, P. (1969) The chromosomes of two species of the genus Oryzomys (Rodentia-Cricetidae). Experientia, 25 (12), 1338 - 1339. https: // doi. org / 10.1007 / BF 01897538","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48.","Baker, R. J., Koop, B. F. & Haiduk, M. W. (1983) Resolving systematic relationships with G-bands: a study of five genera of South American Cricetine rodents. Systematic zoology, 32 (4), 403 - 416. https: // doi. org / 10.2307 / 2413167","Weksler, M. & Bonvicino, C. R. (2015 b) Genus Oligoryzomys Bangs, 1900. In: Patton, J., Pardinas, U. F. J. & D'Elia, G. (Eds.), Mammals of South America. 2. Rodents. University of Chicago Press, Chicago, Illinois, pp. 417 - 437."]}

Oligoryzomys magellanicus Karyotype: 2n = 54 and FN = 66. Autosomal complement: seven metacentric and submetacentric pairs (one very large and the remaining small), and 19 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a medium submetacentric; Y, a small submetacentric (Gallardo & Patterson 1985, pp. 53, Fig. 2)., 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 74, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gallardo, M. H. & Patterson, B. D. (1985) Chromosomal differences between two nominal subspecies of Oryzomys longicaudatus Bennett. Mammalian Chromosomes Newsletter, 25, 49 - 53."]}

Cerradomys vivoi Karyotype: 2n = 50 and FN = 64. Autosomal complement: eight metacentric and submetacentric pairs (one large, four medium, and three small), and 16 acrocentric pairs (one large and remaining medium to small decreasing in size). Sex chromosomes: X, a medium acrocentric; Y, a slightly smaller medium acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of small autosomes, being absent on the large autosomes and on the X chromosome, the Y chromosome had a heterochromatic block distally on the long arm. G-banding was also performed. FISH with telomeric sequences revealed signals at the ends of all chromosome arms, and additional telomeric sequences were found on the centromeric regions of one large and one medium biarmed pairs (Andrades-Miranda et al. 2002, pp. 13, Fig. 2B). The same karyotype was reported by Pereira & Geise (2007). The authors reported a different fundamental number of 66 due to the presence of one small metacentric pair instead of an acrocentric one. Furthermore, they reported a specimen with 2n = 51, with one large acrocentric chromosome without homologous and one more pair of small acrocentric chromosomes. The basic diploid number of 2n = 50 was also reported by Percequillo et al. (2008), who also reported a different fundamental number of 62 due to a presence of one small acrocentric pair instead of a metacentric one, these authors also found a fundamental number of 63 in one male and one female, due to a pericentric inversion involving one chromosome of a medium autosome pair. Another difference was related with the size of Y chromosome smaller on these samples. These variation in diploid and fundamental number of C. vivoi occurs sympatrically on specimens collected in Bahia and Minas Gerais, states of Brazil (Table 2, Fig. 2)., 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 13, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Andrades-Miranda, J., Zanchin, N. I. T., Oliveira, L. F. B., Langguth, A. R. & Mattevi, M. S. (2002) (T 2 AG 3) n telomeric sequence hybridization indicating centric fusion rearrangements in the karyotype of the rodent Oryzomys subflavus. Genetica, 114, 11 - 16. https: // doi. org / 10.1023 / A: 1014645731798","Pereira, L. G. & Geise, L. (2007) Karyotype composition of some rodents and marsupials from Chapada Diamantina (Bahia, Brasil). Brazilian Journal of Biology, 67 (3), 509 - 518. https: // doi. org / 10.1590 / S 1519 - 69842007000300016","Percequillo, A. R., Hingst-Zaher, E. & Bonvicino, C. R. (2008) Systematic review of genus Cerradomys Weksler, Percequillo and Voss, 2006 (Rodentia: Cricetidae: Sigmodontinae: Oryzomyini), with description of two new species from eastern Brazil. American Museum Novitates, 3622, 1 - 46. https: // doi. org / 10.1206 / 495.1"]}

Hylaeamys perenensis Karyotype: 2n = 52 and FN = 62. Autosomal complement: six metacentric and submetacentric pairs medium to small decreasing in size, and 19 acrocentric pairs (one very large and the remaining large to small decreasing in size). Sex chromosomes: X, a large acrocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 6, Fig. 2C; Patton et al. 2000; Volobouev & Aniskin 2000). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes and on the X chromosome. The Y chromosome was entirely heterochromatic. G-banding was also performed (Volobouev & Aniskin 2000). A different fundamental number of 64 was reported by Musser et al. (1998, Malygin 1994 (congress abstract)). The karyotype of H. oniscus and H. perenensis were very similar, however H. perenensis exhibits a distinctly large acrocentric chromosome that was not present in H. oniscus., 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 25, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48.","Patton, J. L., Silva, M. N. & Malcolm, J. R. (2000) Mammals of the Rio Jurua and the evolutionary and ecological diversification of Amazonia. Bulletin of the American Museum of Natural History, 244, 1 - 306. https: // doi. org / 10.1206 / 0003 - 0090 (2000) 244 % 3 C 0001: MOTRJA % 3 E 2.0. CO; 2","Volobouev, V. T. & Aniskin, V. M. (2000) Comparative chromosome banding analysis of three South American species of rice rats of the genus Oryzomys (Rodentia, Sigmodontinae). Chromosome Research, 8, 295 - 304. https: // doi. org / 10.1023 / A: 1009223210737","Musser, G. G., Carleton, M. D., Brothers, E. M. & Gardner, A. L. (1998) Systematic studies of Oryzomyine rodents (Muridae, Sigmodontinae): diagnoses and distributions of species formerly assigned to Oryzomys \" capito \". Bulletin of the American Museum of Natural History, 236, 1 - 376.","Malygin, V. M., Aniskin, V. M., Isaev, S. I. & Milishnikov, A. N. (1994) Amphinectomys savamis Malygin gen. Et sp. n., a new genus and a new species of water rat (Cricetidae, Rodentia) from Peruvian Amazonia. Zoologicheskii zhurnal, 73 (7 & 8), 195 - 208."]}

Oligoryzomys fulvescens Karyotype: 2n = 60 and FN = 74. Autosomal complement: six metacentric and submetacentric pairs (two large, two medium, and two small), three large subtelocentric pairs, and 21 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X chromosome presented two different morphologies, a large subtelocentric, and a large acrocentric; Y, a small acrocentric (Haiduk et al. 1979, pp. 611, Fig. 2A)., 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 62, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Haiduk, M. W., Bickham, J. W. & Schmidly, D. J. (1979) Karyotypes of six species of Oryzomys from Mexico and Central America. Journal of Mammalogy, 60, 610 - 615. https: // doi. org / 10.2307 / 1380103"]}

Hylaeamys seuanezi Karyotype: 2n = 48 and FN = 60. Autosomal complement: seven metacentric pairs medium to small decreasing in size, and 16 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large subtelocentric; Y, a medium metacentric. G-banding was also performed (Weksler et al. 1999, pp. 449, Fig. 2). A similar karyotype was reported by Andrades-Miranda et al. (2000) for samples from Bahia, Brazil. Karyotype: 2n = 48 and FN = 64. Autosomal complement: one large subtelocentric pair, eight pairs of biarmed chromosomes large to small decreasing in size, and 14 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large acrocentric; Y, a medium acrocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes and on the X chromosome. The Y chromosome was entirely heterochromatic. G-banding was also performed. Multiple NORs, varying from three to ten were localized at the telomeric regions of the short arms. According to the authors, the difference in the fundamental number of 60 and 64 was due to the morphology of two autosomal pairs. These variation in fundamental number occurs sympatrically on specimens collected in Bahia, state of Brazil (Table 5, Fig. 6). The same diploid number was reported by Geise & Pereira (2008), but the authors did not provide the fundamental number., 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 25, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Weksler, M., Geise, L. & Cerqueira, R. (1999) A new species of Oryzomys (Rodentia, Sigmondontinae) from southeast Brazil, with comments of the classification of the O. capito species group. Zoological journal of the Linnean Society, 125, 445 - 462. https: // doi. org / 10.1111 / j. 1096 - 3642.1999. tb 00600. x","Andrades-Miranda, J., Zanchin, N. I. T., Oliveira, L. F. B., Langguth, A. R. & Mattevi, M. S. (2000) Cytogenetic studies in nine taxa of the genus Oryzomys (Rodentia, Sigmodontinae) from Brazil. Mammalia, 65 (4), 461 - 472. https: // doi. org / 10.1515 / mamm. 2001.65.4.461","Geise, L. & Pereira, L. G. (2008) Rodents (Rodentia) and marsupials (Didelphimorphia) in the municipalities of Ilheus and Pau Brasil, state of Bahia, Brazil. Check list: journal of species lists and distribution, 4 (2), 174 - 177. https: // doi. org / 10.15560 / 4.2.174"]}

Euryoryzomys Weksler, Percequillo & Voss 2006 The genus Euryoryzomys comprises six species, E. emmonsae (Musser, Carleton, Gardner & Brothers 1998), E. lamia (Thomas 1901), E. legatus (Thomas 1925), E. macconnelli (Thomas 1910), E. nitidus (Thomas 1884), and E. russatus (Wagner 1848). The species inhabit forests throughout the cis Andean tropical and subtropical lowlands of South America, including Amazonia, the Guianas, southeastern Brazil, eastern Bolivia, northern Argentina, and eastern Paraguay (Musser et al. 1998; Weksler et al. 2006; Percequillo 2015c). All cytogenetic data available for the genus was presented on Table 3, and the distribution of diploid and fundamental number of karyotyped specimens were presented on Fig. 3.

Nephelomys meridensis Karyotype: 2n = 66 and FN = 104. Autosomal complement: one medium subtelocentric pair, 19 metacentric and submetacentric pairs medium to small decreasing in size, and 12 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X chromosome presented two different morphologies, a medium metacentric, and a medium acrocentric; Y, a small subtelocentric. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, with the exception of four biarmed pairs which little or no centromeric heterochromatin was found, in addition, some acrocentric pairs presented a lightly stained C-band on distal regions of its long arm. The both X chromosome presented two heterochromatic blocks, one pericentromeric and another distal. The Y chromosome was totally heterochromatic in both cases. G-banding was also performed (Aguilera et al. 1995, pp. 46, Fig. 2B). Another karyotype was also presented by Aguilera et al. (1995), for the samples of western Venezuela, from the Páramo de Tamá. Although distinct from N. meridensis on morphological and karyological traits, specimens of this region were provisionally identified as N. meridensis (Percequillo 2015e), until subsequent analyses validate or reject this hypothesis. Karyotype: 2n = 66 and FN = 92. Autosomal complement: one medium subtelocentric pair, 13 metacentric and submetacentric pairs medium to small decreasing in size, and 18 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a medium acrocentric; Y, unknown as only a female was examined. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes, some acrocentric pairs presented a lightly stained C-band on distal regions of its long arm. The X chromosome presented two heterochromatic blocks, one pericentromeric and another distal. G-banding was also performed (Aguilera et al. 1995, pp. 46, Fig. 2A). Aguilera et al. (1995) analyzed by G-banding these two karyotypes and suggested that the difference in the number of chromosomal arms was possible to be explained due the occurrence of 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 pages 46-47, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Aguilera, M., Perez-Zapata, A. & Martino, A. (1995) Cytogenetics and karyosystematics of Oryzomys albigularis (Rodentia, Cricetidae) from Venezuela. Cytogenetics and cell genetics, 69, 44 - 49. https: // doi. org / 10.1159 / 000133935","Percequillo, A. R. (2015 e) Genus Nephelomys Weksler, Percequillo, & Voss, 2006. In: Patton, J., Pardinas, U. F. J. & D'Elia, G. (Eds.), Mammals of South America. 2. Rodents. University of Chicago Press, Chicago, Illinois, pp. 377 - 390."]}

Euryoryzomys russatus Karyotype: 2n = 80 and FN = 86. Autosomal complement: four small metacentric pairs and 35 acrocentric pairs large to small decreasing in size. Sex chromosomes: X chromosome presented three different morphologies, a large metacentric, a large submetacentric, and a large subtelocentric; Y chromosome presented three different morphologies, a medium submetacentric, a medium-small subtelocentric, and a small acrocentric. The differences on the X chromosome morphology, apparently was due to heterochromatin variation since the C-bands can occur on the centromeric region or the whole short arm can be heterochromatic. NORs bands were detected in two to four small acrocentric pairs. G-banding was also performed (Andrades-Miranda et al. 2000, pp. 465, Fig. 2D). This same karyotype was also reported by Silva et al. (2000), Paresque et al. (2004), Pinheiro & Geise (2008), Di-Nizo et al. (2014), and Gatto-Almeida et al. (2016). A female with 2n = 80/81 being an XX/XXX mosaic was reported by Andrades-Miranda et al. (2000)., 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 16, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Andrades-Miranda, J., Zanchin, N. I. T., Oliveira, L. F. B., Langguth, A. R. & Mattevi, M. S. (2000) Cytogenetic studies in nine taxa of the genus Oryzomys (Rodentia, Sigmodontinae) from Brazil. Mammalia, 65 (4), 461 - 472. https: // doi. org / 10.1515 / mamm. 2001.65.4.461","Silva, M. J. J., Percequillo, A. R. & Yonenaga-Yassuda, Y. (2000) Cytogenetics and systematic approach on a new Oryzomys species, of the nitidus group (Sigmodontinae, Rodentia) from Northeastern Brazil. Caryologia, 53, 219 - 226. https: // doi. org / 10.1080 / 00087114.2000.10589199","Paresque, R., Souza, W. P., Mendes, S. L. & Fagundes, V. (2004) Composicao cariotipica da fauna de roedores e marsupiais de duas areas de Mata Atlantica do Espirito Santo, Brasil. Boletim do Museu de Biologia Mello Leitao, 17, 5 - 33.","Pinheiro, P. S. & Geise, L. (2008) Non-volant mammals of Picinguaba, Ubatuba, state of Sao Paulo, southeastern Brazil. Boletim do Museu de Biologia Mello Leitao, 23, 51 - 59.","Di-Nizo, C. B., Neves, C. L., Vilela, J. F. & Silva, M. J. J. (2014) New karyologycal data and cytotaxonomic considerations on small mammals from Santa Virginia (Parque Estadual da Serra do Mar, Atlantic Forest, Brazil). Comparative cytogenetics, 8 (1), 11 - 30. https: // doi. org / 10.3897 / compcytogen. v 8 i 1.6430","Gatto-Almeida, F., Pontes, J. S., Sbalqueiro, I. J., Hass, I., Tiepolo, L. M. & Quadros, J. (2016) Diversidade, biogeografia, caracterizacao cariotipica e tricologica dos pequenos mamiferos nao voadores do Parque Estadual Rio da Onca, Litoral Sul do Parana. Papeis avulsos de zoologia, 56 (7), 69 - 96. https: // doi. org / 10.11606 / 0031 - 1049.2016.56.07"]}

Neacomys rosalindae Karyotype: 2n = 48 and FN = 50. Autosomal complement: two small metacentric pairs, and 21 acrocentric pairs (one large, and the remaining medium to small decreasing in size). Sex chromosomes: X, a medium submetacentric; Y, a small acrocentric (Sánchez-Vendizú et al. 2018, pp. 16, Fig. 7A)., 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 34, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Sanchez-Vendizu, P., Pacheco, V. & Vivas-Ruiz, D. (2018) An Introduction to the Systematics of Small-Bodied Neacomys (Rodentia: Cricetidae) from Peru with Descriptions of Two New Species. American Museum Novitates, 3913, 1 - 39. https: // doi. org / 10.1206 / 3913.1"]}

Oligoryzomys vegetus According to the Rogers et al. (2009), the karyotype reported by Gardner & Patton (1976) for O. fulvescens from Costa Rica actually represents O. vegetus. Karyotype: 2n = 54 and FN = 68. Autosomal complement: five metacentric and submetacentric pairs (one large and four medium to small), three large subtelocentric pairs, and 18 small acrocentric pairs. Sex chromosomes: X, a medium acrocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 8, Fig. 3F)., 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 76, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Rogers, D. S., Arenas, E. A., Gonzalez-Cozatl, F. X., Hardy, D. K., Hanson, J. D. & Lewis-Rogers, N. (2009) Molecular phylogenetics of Oligoryzomys fulvescens based on cytochrome b gene sequences, with comments on the evolution of the genus Oligoryzomys. Cervantes, F, ed, 60, 1 - 14.","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48."]}

Oligoryzomys longicaudatus Karyotype: 2n = 56 and FN = 66. Autosomal complement: six small metacentric and submetacentric pairs, and 21 acrocentric pairs (one large and the remaining medium to small decreasing in size). Sex chromosomes: X chromosome presented two different morphologies, a medium submetacentric, and a medium subtelocentric; Y chromosome presented two different morphologies, a small submetacentric, and a small subtelocentric (Gallardo & González 1977, pp. 313, Fig. 1A; Gallardo & Patterson 1985; Espinosa & Reig 1991; Palma et al. 2005; Belmar-Lucero et al. 2009; Palma & Rodríguez-Serrano 2017). Espinosa & Reig (1991) also reported a different fundamental number of 64 for a sample from Rio Negro, state of Argentina, according to the authors this difference was probably due to a pericentric inversion involving an autosomal pair. G-banding was also performed., 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 74, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gallardo, M. H. & Patterson, B. D. (1985) Chromosomal differences between two nominal subspecies of Oryzomys longicaudatus Bennett. Mammalian Chromosomes Newsletter, 25, 49 - 53.","Espinosa, M. B. & Reig, O. A. (1991) Cytogenetics and karyosystematics of South American oryzomyine rodents (Cricetidae, Sigmodontinae) III. Banding karyotypes of Argentinian Oligoryzomys. Zeitschrift fur Saugetierkunde, 56, 306 - 317.","Palma, R. E., Rivera-Milla, E., Salazar-Bravo, J., Torres-Perez, F., Pardinas, U. F. J., Marquet, P. A., Spotorno, A. E., Meynard, A. P. & Yates, T. L. (2005) Phylogeography of Oligoryzomys longicaudatus (Rodentia: Sigmodontinae) in temperate South America. Journal of Mammalogy, 86 (1), 191 - 200. https: // doi. org / 10.1644 / 1545 - 1542 (2005) 086 % 3 C 0191: POOLRS % 3 E 2.0. CO; 2","Belmar-Lucero, S., Godoy, P., Ferres, M., Vial, P. & Palma, E. (2009) Range expansion of Oligoryzomys longicaudatus (Rodentia, Sigmodontinae) in Patagonian Chile, and first record of Hantavirus in the region. Revista chilena de historia natural, 82, 265 - 275. https: // doi. org / 10.4067 / S 0716 - 078 X 2009000200008","Palma, R. E. & Rodriguez-Serrano, E. (2017) Systematics of Oligoryzomys (Rodentia, Cricetidae, Sigmodontinae) from southern Chilean Patagonia, with the description of a new species. Journal of Zoological Systematics and Evolutionary Research, 56 (2), 280 - 299. https: // doi. org / 10.1111 / jzs. 12199"]}

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., 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 20, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Nachman, M. W. (1992 a) Geographic patterns of chromosomal variation in South American marsh rats, Holochilus brasiliensis and H. vulpinus. Cytogenetics and Cell Genetics, 61, 10 - 16. https: // doi. org / 10.1159 / 000133361","Riva, R., Vidal, O. R. & Bard, N. I. (1977) Los cromosomas del genero Holochilus. II. El cariotipo de H. brasiliensis vulpinus. Physis Buenos Aires, 36, 215 - 218."]}

Oecomys trinitatis Karyotype: 2n = 58 and FN = 96. Autosomal complement: 16 metacentric and submetacentric pairs large to small decreasing in size, four subtelocentric pairs large to medium decreasing in size, and eight acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a large submetacentric (the largest chromosome of the complement); Y, a small acrocentric (Patton et al. 2000, pp. 132, Fig. 91). The karyotype of an undescribed species was reported by Patton et al. (2000, pp. 128, Fig. 88). Karyotype: 2n = 86 and FN = 98. Autosomal complement: seven small metacentric and submetacentric pairs, and 35 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a large subtelocentric; Y, unknown as only females was analyzed. Two additional karyotypes attributed to a presumptive new species of Oecomys, with 2n=54, FN=84 and 2n=54, FN=86, were presented by Gomes-Júnior et al. (2016; unpublished data from T. Lira) for populations from Amazonas, Brazil. Based on our sampling efforts, we present three different karyotypes for the genus, mentioned here as Oecomys sp. 1, Oecomys sp. 2 and Oecomys sp. 3. The cytogenetic analyzes were performed for specimens collected in the Rio Japurá and Rio Içá, Amazonas state of Brazil (Table 1)., 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 56, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Patton, J. L., Silva, M. N. & Malcolm, J. R. (2000) Mammals of the Rio Jurua and the evolutionary and ecological diversification of Amazonia. Bulletin of the American Museum of Natural History, 244, 1 - 306. https: // doi. org / 10.1206 / 0003 - 0090 (2000) 244 % 3 C 0001: MOTRJA % 3 E 2.0. CO; 2","Gomes-Junior, R. G., Schneider, C. H., Lira, T., Carvalho, N. D. M., Feldberg, E., Silva, M. N. F. & Gross, M. C. (2016) Intense genomic reorganization in the genus Oecomys (Rodentia, Sigmodontinae): comparison between DNA barcoding and mapping of repetitive elements in three species of the Brazilian Amazon. Comparative cytogenetics, 10 (3), 401 - 426. https: // doi. org / 10.3897 / compcytogen. v 10 i 3.8306"]}

Oligoryzomys brendae Karyotype: 2n = 58 and FN = 74. Autosomal complement: nine metacentric and submetacentric pairs (two large and remaining small), and 19 acrocentric pairs (one large and the remaining small). Sex chromosomes: X, a medium submetacentric; Y, a small acrocentric. G-banding was also performed (Espinosa & Reig 1991, pp. 311, Fig. 3A; Teta et al. 2013)., 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 60, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Espinosa, M. B. & Reig, O. A. (1991) Cytogenetics and karyosystematics of South American oryzomyine rodents (Cricetidae, Sigmodontinae) III. Banding karyotypes of Argentinian Oligoryzomys. Zeitschrift fur Saugetierkunde, 56, 306 - 317.","Teta, P., Jayat, J. P., Ortiz, P. E. & D'Elia, G. (2013) The taxonomic status of Oligoryzomys brendae Massoia, 1998 (Rodentia, Cricetidae), with comments on the availability of this name. Zootaxa, 3641 (4), 433 - 447. https: // doi. org / 10.11646 / zootaxa. 3641.4.9"]}

Zygodontomys brevicauda (Z. b. brevicauda) Two different karyotypes were reported for Z. b. brevicauda. Karyotype 1: 2n = 84 and FN = 116 or 118. Autosomal complement: one medium submetacentric pair, one medium subtelocentric pair, 18 small autosomal pairs, and 21 minute autosomal pairs. According to authors, due to the small size of most autosomes, it was hard to recognize the morphology of many of the chromosomal pairs, however based on the best-defined karyotypes the estimate of autosomal fundamental number as made of 116 or 118 arms. Sex chromosomes: X, a small subtelocentric; Y, a minute subtelocentric (Kiblisky et al. 1970; Reig et al. 1990, pp. 363, Fig. 2). A secondary constriction was observed at one small autosomal pair. C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of almost all chromosomes, the medium metacentric and submetacentric pairs lack a striking heterochromatic region, five small autosomal pairs exhibit both pericentromeric and terminal heterochromatic block, three small to minute autosomal pairs presented the small arm entirely heterochromatic, five minute autosomal pairs were entirely heterochromatic, all the remaining autosomal pairs showed different degrees of Cband on the pericentromeric regions. The X chromosome presented a pericentromeric heterochromatic block, and the banding pattern of the Y chromosome was not clearly defined. According to authors, the heterochromatic nature of some short arms, may be responsible for polymorphic variants in the morphology of several autosomes among different individuals (Reig et al. 1990). Karyotype 2: 2n = 88 and FN = 116–118. Autosomal complement: one medium submetacentric pair, one medium subtelocentric pair, 18 small autosomal pairs, and 23 minute autosomal pairs. Sex chromosomes: X, a small subtelocentric; Y, a minute subtelocentric (Gardner & Patton 1976; Perez-Zapata et al. 1984; Reig et al. 1990, pp. 365, Fig. 4). According to Reig et al. (1990), the difference in diploid numbers of 2n = 84 and 2n = 88, that occurs in different localities of Venezuela (Table 11, Fig. 22), were due to addition of two pairs of minute chromosomes. Besides, the metacentric and the submetacentric small pairs found in the 2n = 84 karyotype was lacking in the 2n = 88 karyotype. These differences can be easily explained by a Robertsonian rearrangement affecting two small pairs of the 2n = 84 karyotype. C-banding was performed and a great deal of the genome were C-band positive, although the small size and high number of chromosomes hampered efforts to obtain a clear metaphase. It was evident, however, that eleven very minute autosome pairs were entirely heterochromatic, and five small autosome pairs appear to be entirely heterochromatic (Reig et al. 1990)., 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 82, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Kiblisky, P., Lobig, I. & Reig, O. A. (1970) Estudio cromosomico en diversas poblaciones del raton Ilanero Zygodontomys microtinus Thomas. Acta Cientifica Venezolana, 21, 35.","Reig, O. A., Aguilera, M. & Perez-Zapata, A. (1990) Cytogenetics and karyosystematics of South American oryzomyine rodents (Cricetidae: Sigmodontinae) II. High numbered karyotypes and chromosomal heterogeneity in Venezuelan Zygodontomys. Zeitschrift fur Saugetierkunde, 55 (6), 361 - 370.","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48.","Perez-Zapata, A., Aguilera, M., Ferrer, A. & Reig, O. A. (1984) El cariotipo de una poblacion de Zygodontomys sp. (Rodentia, Cricetidae) del Delta del Orinoco. Acta Cientifica Venezolana, 35, 227."]}

Oligoryzomys yatesi Karyotype: 2n = 54 and FN = 66. Autosomal complement: seven biarmed pairs (one very large and the remaining small), and 19 acrocentric pairs decreasing in size. Sex chromosomes: X and Y were subtelocentrics (Palma & Rodríguez-Serrano 2017, pp. 6, Fig. 2A). According to the authors, this karyotype was very similar with the karyotype of O. magellanicus reported by Gallardo & Peterson (1985). The karyotype of two more undescribed species were reported by Gardner & Patton (1976) and Andrades-Miranda et al. (2001a)., 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 76, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Palma, R. E. & Rodriguez-Serrano, E. (2017) Systematics of Oligoryzomys (Rodentia, Cricetidae, Sigmodontinae) from southern Chilean Patagonia, with the description of a new species. Journal of Zoological Systematics and Evolutionary Research, 56 (2), 280 - 299. https: // doi. org / 10.1111 / jzs. 12199","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48.","Andrades-Miranda, J., Oliveira, L. F. B., Lima-Rosa, C. A., Nunes, A. P., Zanchin, N. I. T. & Mattevi, M. S. (2001 a) Chromosome studies of seven species of Oligoryzomys (Rodentia: Sigmodontinae) from Brazil. Journal of Mammalogy, 82, 1080 - 1091. https: // doi. org / 10.1644 / 1545 - 1542 (2001) 082 % 3 C 1080: CSOSSO % 3 E 2.0. CO; 2"]}

Nephelomys keaysi Karyotype: 2n = 80 and FN = 92. Autosomal complement: seven medium to small metacentric and submetacentric pairs, and 32 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a very large subtelocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 4, Fig. 1C)., 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 46, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48."]}

Amphinectomys Malygin, Aniskin, Isaev & Milishnikov 1994 Monotypic genus represented by A. savamis (Malygin, Aniskin, Isaev & Milishnikov 1994), known from only a few specimens collected in Ecuador and northeastern Peru, Departamento Loreto and Departamento Ucayali (in the Sierra del Divisor), near the Peruvian-Brazilian border (Malygin et al. 1994; Weksler & Valqui 2015; Chiquito & Percequillo 2016). Karyotype: 2n = 50 and FN = 62.Autosomal complement: four submetacentric pairs (three large and one small), two small metacentric pairs, one small subtelocentric pair, and 17 acrocentric pairs (seven large to small and ten very small). Sex chromosomes: X, a metacentric (the largest chromosome of the complement); Y, a large metacentric (Malygin et al. 1994, Fig. 6I). C- and G-banding were also performed (Malygin et al. 1994; O’Brien et al. 2006, pp. 194).

Euryoryzomys macconnelli Karyotype: 2n = 64 and FN = 64, according to Gardner & Patton (1976), who originally described this karyotype for Peruvian samples, the chromosomal preparation from the only specimen examined did not permit unequivocal identification of the morphologies of all the chromosomes. Nevertheless, the diploid number was clearly 64 and the karyotype appears to consists of one small metacentric pair and 31 acrocentric pairs large to small decreasing in size. Since it was unlikely that the small metacentric pair represent the sex chromosome, the X and Y were probably acrocentric and the FN was given as 64 (Gardner & Patton 1976, pp. 8). The same karyotype was reported some years later by Silva et al. (2000, pp. 224) for samples from Mato Grosso, Brazil. The same diploid number was described by Musser et al. (1998, pp. 231, Fig. 105) for populations from western Brazil, with a different fundamental number. Karyotype: 2n = 64 and FN = 70. Autosomal complement: four medium to small metacentric and submetacentric pairs, and 27 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large subtelocentric; Y, a small acrocentric (Musser et al. 1998). According to the authors, the karyotype of the Peruvian specimen, reported by Gardner & Patton (1976) has the same diploid number, but because the Brazilian animals have four pairs of biarmed autosomes instead of the single pair reported for the Peruvian animal, the fundamental number was 70 instead of 64. Additional preparations from Peruvian specimens may show the reported differences to be an artefact of the poor quality of original chromosomal slides (Musser et al. 1998). The specimens collected in Venezuela by Musser et al. (1998, pp. 231, Fig. 105) presented another different karyotype. Karyotype: 2n = 76 and FN = 85. Autosomal complement: five small metacentric and submetacentric pairs, 31 acrocentric pairs large to small decreasing in size, and two unpaired chromosomes, a medium-sized metacentric and a medium-sized acrocentric. Sex chromosomes: X, a large subtelocentric; Y, a small acrocentric. According to the authors, several pairs of acrocentric autosomes bear discernible second arms and could be classed as biarmed chromosome, thus raising the FN to as high as 107 (Musser et al. 1998). Another different karyotype was mentioned by Patton et al. (2000, pp. 143), from samples for Rio Jaú, Amazonas. Karyotype: 2n = 58 and NF = 90, the information was not available in literature, as Patton et al. (2000) informed that this represents unpublished data provided by M.N.F. Silva. These variation in diploid and fundamental number of E. macconnelli occurs in different localities of Amazon rainforest (Table 3, Fig. 3)., 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 pages 15-16, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48.","Silva, M. J. J., Percequillo, A. R. & Yonenaga-Yassuda, Y. (2000) Cytogenetics and systematic approach on a new Oryzomys species, of the nitidus group (Sigmodontinae, Rodentia) from Northeastern Brazil. Caryologia, 53, 219 - 226. https: // doi. org / 10.1080 / 00087114.2000.10589199","Musser, G. G., Carleton, M. D., Brothers, E. M. & Gardner, A. L. (1998) Systematic studies of Oryzomyine rodents (Muridae, Sigmodontinae): diagnoses and distributions of species formerly assigned to Oryzomys \" capito \". Bulletin of the American Museum of Natural History, 236, 1 - 376.","Patton, J. L., Silva, M. N. & Malcolm, J. R. (2000) Mammals of the Rio Jurua and the evolutionary and ecological diversification of Amazonia. Bulletin of the American Museum of Natural History, 244, 1 - 306. https: // doi. org / 10.1206 / 0003 - 0090 (2000) 244 % 3 C 0001: MOTRJA % 3 E 2.0. CO; 2"]}

Hylaeamys oniscus Karyotype: 2n = 52 and FN = 62. Autosomal complement: six metacentric and submetacentric pairs medium to small decreasing in size, and 19 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large acrocentric; Y, a small acrocentric (Maia 1990, pp. 379, Fig. 1A; Andrades-Miranda et al. 2000). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes and on the X chromosome. The Y chromosome was entirely heterochromatic. G-banding was also performed. Multiple NORs, varying from five to nine were localized at the telomeric regions of the short arms of acrocentric pairs (Andrades- Miranda et al. 2000)., 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 25, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Maia, V. (1990) Karyotype of Oryzomys capito oniscus (Rodentia) from Northeastern Brazil. Revista Brasileira de Genetica, 13, 377 - 382.","Andrades-Miranda, J., Zanchin, N. I. T., Oliveira, L. F. B., Langguth, A. R. & Mattevi, M. S. (2000) Cytogenetic studies in nine taxa of the genus Oryzomys (Rodentia, Sigmodontinae) from Brazil. Mammalia, 65 (4), 461 - 472. https: // doi. org / 10.1515 / mamm. 2001.65.4.461"]}

Holochilus sp. An unnamed form mentioned by Gardner & Patton (1976) for Villavicencio, Colombia, was believed to constitute a cytogenetically different species, with 2n = 50 and FN = 58 an acrocentric X and a metacentric Y (Gonçalves et al. 2015). ......continued on the next page ......continued on the next page A detailed analysis of Robertsonian rearrangements on meiosis of Holochilus species was reported by Nachman (1992b) and more details about the karyotype evolution and variability of the genus was reported by Aguilera et al. (1993)., 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 pages 20-24, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in Oryzomyine rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical Cricetine complex. Occasional papers of the Museum of Zoology, 49, 1 - 48.","Goncalves, P. R., Teta, P. & Bonvicino, C. R. (2015) Genus Holochilus Brandt, 1835. In: Patton, J., Pardinas, U. F. J. & D'Elia, G. (Eds.), Mammals of South America. 2. Rodents. University of Chicago Press, Chicago, Illinois, pp. 325 - 335.","Freitas, T. R. O., Mattevi, M. S., Oliveira, L. F. B., Souza, M. J., Yonenaga-Yassuda, Y. & Salzano, F. M. (1983) Chromosome relationships in three representatives of the genus Holochilus (Rodentia, Cricetidae) from Brazil. Genetica, 61, 13 - 20. https: // doi. org / 10.1007 / BF 00563228","Nachman, M. W. (1992 a) Geographic patterns of chromosomal variation in South American marsh rats, Holochilus brasiliensis and H. vulpinus. Cytogenetics and Cell Genetics, 61, 10 - 16. https: // doi. org / 10.1159 / 000133361","Nachman, M. W. & Myers, P. (1989) Exceptional chromosomal mutations in a rodent population are not strongly underdominant. Proceedings of the National Academy of Sciences, 86, 6666 - 6670. https: // doi. org / 10.1073 / pnas. 86.17.6666","Vidal, O. R., Riva, R. & Baro, N. I. (1976) Los cromosomas del genero Holochilus. I. Polimorfismo en H. chacarius Thomas (1906). Physis, 35, 75 - 85.","Patton, J. L., Silva, M. N. & Malcolm, J. R. (2000) Mammals of the Rio Jurua and the evolutionary and ecological diversification of Amazonia. Bulletin of the American Museum of Natural History, 244, 1 - 306. https: // doi. org / 10.1206 / 0003 - 0090 (2000) 244 % 3 C 0001: MOTRJA % 3 E 2.0. CO; 2","Yonenaga-Yassuda, Y., Prado, R. C. & Mello, D. A. (1987) Supernumerary chromosomes in Holochilus brasiliensis and comparative cytogenetic analysis with Nectomys squamipes (Cricetidae, Rodentia). Revista Brasileira de Genetica, 2, 209 - 220.","Baker, R. J., Koop, B. F. & Haiduk, M. W. (1983) Resolving systematic relationships with G-bands: a study of five genera of South American Cricetine rodents. Systematic zoology, 32 (4), 403 - 416. https: // doi. org / 10.2307 / 2413167","Sangines, M. & Aguilera, M. (1991) Chromosome polymorphism in Holochilus venezuelae (Rodentia: Cricetidae): C- and Gbands. Genome, 34, 13 - 18. https: // doi. org / 10.1139 / g 91 - 003","Aguilera, M. & Perez-Zapata, A. (1989) Cariologia de Holochilus venezuelae (Rodentia, Cricetidae). Acta cientifica venezolana, 40, 198 - 207.","Riva, R., Vidal, O. R. & Bard, N. I. (1977) Los cromosomas del genero Holochilus. II. El cariotipo de H. brasiliensis vulpinus. Physis Buenos Aires, 36, 215 - 218.","Nachman, M. W. (1992 b) Meiotic studies of Robertsonian polymorphisms in the South American marsh rat, Holochilus brasiliensis. Cytogenetics and Cell Genetics, 61, 17 - 24. https: // doi. org / 10.1159 / 000133362","Aguilera, M., Perez-Zapata, A., Sangines N. & Martino A. (1993) Citogenetica evolutiva en dos generos de roedores suramericanos: Holochilus y Proechimys. Boletin de la Sociedad Zoologica del Uruguay, 8, 49 - 61."]}

Nephelomys Weksler, Percequillo & Voss 2006 The genus Nephelomys comprises 13 recognized species, N. albigularis (Tomes 1860), N. auriventer (Thomas 1899), N. caracolus (Thomas 1914), N. childi (Thomas 1895), N. devius (Bangs 1902), N. keaysi (Allen 1900), N. levipes (Thomas 1902), N. maculiventer (Allen 1899), N. meridensis (Thomas 1894), N. moerex (Thomas 1914), N. nimbosus (Anthony 1926), N. pectoralis (Allen 1912), and N. pirrensis (Goldman 1913). These species were restricted to the Andes, from Bolivia to Colombia, the coastal ranges of Venezuela, and extend northwards in the cordilleras of Panama and Costa Rica in Central America (Márquez et al. 2000; Weksler et al. 2006 b; Prado & Percequillo 2013; Percequillo 2015e)., 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 46, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Weksler, M., Percequillo, A. R. & Voss, R. S. (2006) Ten new genera of oryzomyine rodents (Cricetidae: Sigmodontinae). Bulletin of the American Museum of Natural History, 3537, 1 - 29.","Marquez, E. J., Aguilera, M. & Corti, M. (2000) Morphometric and chromosomal variation in populations of Oryzomys albigularis (Muridae: Sigmodontinae) from Venezuela: multivariate aspects. Zeitschrift fur Saugetierkunde, 65, 84 - 99.","Prado, J. R. & Percequillo, A. R. (2013) Geographic distribution of the genera of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae) in South America: patterns of distribution and diversity. Archivos de Zoologia, 44 (1), 1 - 120. https: // doi. org / 10.11606 / issn. 2176 - 7793. v 44 i 1 p 1 - 120","Percequillo, A. R. (2015 e) Genus Nephelomys Weksler, Percequillo, & Voss, 2006. In: Patton, J., Pardinas, U. F. J. & D'Elia, G. (Eds.), Mammals of South America. 2. Rodents. University of Chicago Press, Chicago, Illinois, pp. 377 - 390."]}

Euryoryzomys sp. Karyotype: 2n = 58 and FN = 92. Autosomal complement: 18 biarmed pairs large to small decreasing in size, and 10 acrocentric pairs medium to small decreasing in size. Sex chromosomes: X, a large submetacentric; Y, a small submetacentric (Fig. 4A). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of the majority of autosomal pairs. One large submetacentric pair presented a pericentromeric heterochromatin block that extend to the short arm. The X chromosome presented the short arm entirely heterochromatic and an interstitial lightly stained C-band on its long arm. The Y chromosome presented the long arm entirely heterochromatic (Fig. 4B). G-banding was performed to allow the correct identification of all homologous pairs (Fig. 4C). FISH with telomeric sequences revealed signals at the ends of all chromosome arms, and additional telomeric sequences were found on the centromeric regions of one large and one small biarmed pairs (Fig. 4D). This karyotype could be a variation of E. macconnelli (2n=58 and NF=90) mentioned by Patton et al. (2000, pp. 143), and the difference in fundamental number resulted from a pericentric inversion involving one biarmed autosomal pair. However, was not possible to compare these two karyotypes since the metaphase plate of the karyotype mentioned by Patton et al. (2000) was not available.