Advances in cytogenetics of Brazilian rodents: cytotaxonomy, chromosome evolution and new karyotypic data

Abstract

Rodents constitute one of the most diversified mammalian orders. Due to the morphological similarity in many of the groups, their taxonomy is controversial. Karyotype information proved to be an important tool for distinguishing some species because some of them are species-specific. Additionally, rodents can be an excellent model for chromosome evolution studies since many rearrangements have been described in this group.This work brings a review of cytogenetic data of Brazilian rodents, with information about diploid and fundamental numbers, polymorphisms, and geographical distribution. We point out that, even with the recent efforts on cytogenetic studies in this group, many species lack karyotypic data. Moreover, we describe for the first time the karyotype of Carterodon sulcidens (Lund, 1838) (Family Echimyidae), a new fundamental number for an undescribed species of Neacomys Thomas, 1900 (Family Cricetidae, Subfamily Sigmodontinae), and illustrate the karyotype of a Brazilian specimen of Mus musculus Linnaeus, 1758 (Family Muridae). This review compiles the cytogenetic data on Brazilian rodents reported in the last three decades, after the last revision published in 1984, including synonyms, chromosomal variations, and geographic distribution. Additionally, it also reinforces that Brazilian biodiversity is still poorly known, considering the new data reported here.

Chromatic anomalies in Akodontini (Cricetidae: Sigmodontinae)

“…Species identification was confirmed through comparisons with skulls of A. cursor specimens from the mammalian collections, as well as through microscopic analyses of the chromosomes after Giemsa stain procedure, following the morphological classification proposed by Levan et al (1964). The specimen presented diploid number (2n)=14 and fundamental number (NF)=20, which is in agreement with karyotypic data reported for A. cursor (Di-Nizo et al, 2017). Skull, skin, and tissues of the specimen were deposited into the mammalian collection of "Museu de Zoologia João Moojen da Universidade Federal de Viçosa" (MZUFV 4423), Viçosa, Minas Gerais state, Brazil ( Figure 1A).…”

Systematics of Neotropical Spiny Mice, Genus Neacomys Thomas, 1900 (Rodentia: Cricetidae), from Southeastern Amazonia, with Descriptions of Three New Species

“…5). According to cytogenetic data (Di-Nizo et al, 2017;Oliveira da Silva et al, 2019), the species also ranges southward into Vila Rica in northeastern Mato Grosso state. These records suggest that the species is restricted to the Xingu center of endemism (Silva et al, 2005).…”

“…(2015), "Neacomys sp. " by Di-Nizo et al (2017) and Brandão et al (2019), and "Neacomys sp. C" by Oliveira da Silva et al (2019).…”

Chromosomal Signatures Corroborate the Phylogenetic Relationships within Akodontini (Rodentia, Sigmodontinae)

“…In attempting to review the cytogenetic data of Oxymycterus, Di-Nizo et al [43] listed 2n = 54 for O. amazonicus; however, the sources cited for this information do not describe the karyotype of this taxon [19,36]. In fact, Bonvicino et al [36] (Table 2), exhibit at least one large submetacentric (pair 1), and range from three to five bi-armed chromosomes.…”