The rodent subfamily Sigmodontinae includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species count numbers at least 508. Their distribution includes much of the New World, but the genera are predominantly South American, such as brucies. They invaded South America from Central America as part of the Great American Interchange near the end of the Miocene, about 5 million years ago. Sigmodontines proceeded to diversify explosively in the formerly isolated continent. They inhabit many of the same ecological niches that the Murinae occupy in the Old World.
Necromys is a genus of South American sigmodontine rodents allied to Akodon. This genus has also been known as Cabreramys or more recently Bolomys, and the northern grass mouse has recently been transferred from Akodon.
Spix's yellow-toothed cavy is a rodent, a cavy species from South America. It is found in Bolivia east of the Andes and much of south central to northeastern Brazil. The species is found in open savanna and semiarid habitats, such as the Cerrado and Caatinga of Brazil. Its karyotype is 2n = 64 and FN = 118.
The cursor grass mouse, or cursorial akodont, is a sigmodontine rodent from South America.
Euryoryzomys emmonsae, also known as Emmons' rice rat or Emmons' oryzomys, is a rodent from the Amazon rainforest of Brazil in the genus Euryoryzomys of the family Cricetidae. Initially misidentified as E. macconnelli or E. nitidus, it was formally described in 1998. A rainforest species, it may be scansorial, climbing but also spending time on the ground. It lives only in a limited area south of the Amazon River in the state of Pará, a distribution that is apparently unique among the muroid rodents of the region.
Euryoryzomys russatus, also known as the russet oryzomys, russet rice rat, or big-headed rice rat, is a species of rodent in the family Cricetidae. It is a member of the genus Euryoryzomys, which was split off from Oryzomys in 2006. It was first described by Johann Andreas Wagner in 1848. It is found in southern Brazil, eastern Paraguay and northeastern Argentina. It is considered a large species in its genus, with a reddish-brown coat, long tail length, and large skull. It is a terrestrial rodent, spending its time foraging for seeds, fruits, and insects. It is listed by the IUCN as least concern, although studies have shown it to be influenced by anthropogenic disturbances. Predators consist of small members of the order Carnivora.
The large vesper mouse is a South American rodent species of the family Cricetidae.
The delicate vesper mouse is a South American rodent species of the family Cricetidae. It is found in Argentina, Bolivia and Brazil. Its karyotype has 2n = 66 and FN = 66.
The Tocantins vesper mouse is a South American rodent species of the family Cricetidae. It is found in Brazil. Its karyotype has 2n = 46 and FNa = 66.
The lesser Wilfred's mouse is a species of South American rodents of the family Cricetidae. It was first described by Wilfred H. Osgood under the name Thomasomys pictipes, then into the genus Wilfredomys, and now known as Juliomys pictipes. The lesser Wilfred's mouse is endemic to northeastern Argentina and southeastern Brazil. Its physical appearance ranges from dark brown to light orange coloration and the typical size is small to medium. This species is arboreal, spending most of its time trees and living in the local forests at altitudes from sea level to 2000 m. Currently, this species is listed as Least Concern by the IUCN, but, threats include livestock farming, ranching, and wood harvesting.
Scolomys ucayalensis, also known as the long-nosed scolomys or Ucayali spiny mouse is a nocturnal rodent species from South America. It is part of the genus Scolomys within the tribe Oryzomyini. It is found in Brazil, Colombia, Ecuador and Peru in various different habitats in the Amazon rainforest.
Pseudoryzomys simplex, also known as the Brazilian false rice rat or false oryzomys, is a species of rodent in the family Cricetidae from south-central South America. It is found in lowland palm savanna and thorn scrub habitats. It is a medium-sized species, weighing about 50 grams (1.8 oz), with gray–brown fur, long and narrow hindfeet, and a tail that is about as long as the head and body. The IUCN has assessed its conservation status as being of least concern, although almost nothing is known about its diet or reproduction.
Transandinomys talamancae is a rodent in the family Cricetidae that occurs from Costa Rica to southwestern Ecuador and northern Venezuela. Its habitat consists of lowland forests up to 1,500 m (5,000 ft) above sea level. With a body mass of 38 to 74 g, it is a medium-sized rice rat. The fur is soft and is reddish to brownish on the upperparts and white to buff on the underparts. The tail is dark brown above and lighter below and the ears and feet are long. The vibrissae (whiskers) are very long. In the skull, the rostrum is long and the braincase is low. The number of chromosomes varies from 34 to 54.
Scolomys melanops, also known as the short-nosed scolomys, South American spiny mouse, Ecuadorian spiny mouse, or gray spiny mouse, is a species of rodent in the genus Scolomys of family Cricetidae. It is a forest mouse and was thought to be endemic to Ecuador but it is now known to have a wider distribution, being also present in part of Peru.
The cerrado climbing mouse or long-tailed rhipidomys is an arboreal rodent species in the family Cricetidae from South America. It is found in primary or secondary forests of the cerrado and caatinga in central and eastern Brazil, and has also been seen in the Atlantic Forest. Its karyotype is 2n = 44, FN = 48-52. They are nocturnal animals and can be found in both tree canopies and on the ground.
The montane Atlantic Forest rat is a South American rodent species of the family Cricetidae. It is endemic to part of the Atlantic Forest region of southeastern Brazil, where it is found at elevations from 1000 to 2700 m in noncontiguous mountain ranges. Its karyotype, like that of closely related Delomys dorsalis, has 2n = 82, but the fundamental numbers of the two species differ. While it is not thought to be in present danger of extinction, habitat destruction and grassland fires are considered to be threats.
The delicate salt flat mouse is a sigmodontine rodent species in the family Cricetidae from South America. It is the only species in the genus Salinomys. Its habitat is scrublands bordering salt flats in the Monte Desert area of central western Argentina at elevations around 400 m. The closest relatives of the species are the chaco mice (Andalgalomys).
The highlands punaré is a caviomorph rodent of South America from the spiny rat family. It is endemic to gallery forest, savanna and rocky outcrop habitats in Bahia State within the Caatinga ecoregion of eastern Brazil at elevations from 260 m to 1030 m. It sometimes nests and often takes refuge in crevices in rock formations, as means of both predator avoidance and moderating temperature extremes. The species tolerates a degree of habitat disturbance. Although hunted, it is considered common throughout its range. Its karyotype has 2n = 26 and FN = 48.
The fecund vesper mouse is a species of rodent in the family Cricetidae. It is known only from Bolivia, where it is found in the yungas and Tucumano boliviano forest ecoregions at elevations from 600 to 2700 m. It is regarded by some authorities as conspecific with C. boliviae, and by some as conspecific with C. venustus, despite having a karyotype with 2n = 54 while C. venustus generally has a karyotype with 2n = 56.
Calomys cerqueirai is a species of rodent in the genus Calomys from southeastern Brazil. Distinct from other Calomys in its karyotype and characters of the fur, it is known only from two places in Minas Gerais. The karyotype was first described in 1996 and the species was formally named in 2010.
