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.
The Brazilian shrew mouse, also known as the blarinine akodont, is a rodent in the tribe Akodontini from the Atlantic Forest of eastern and southeastern Brazil. It is the only species in the genus Blarinomys. Phylogenetic analysis suggest that there are two clear geographical clades, a northeastern and southeastern.
The Togo mouse, also known as Büttner's African forest mouse or the groove-toothed forest mouse, is a unique muroid rodent known from only two specimens taken from near the type locality of Bismarckburg, near Yege, Togo, in 1890. Its genus is monotypic.
The cursor grass mouse, or cursorial akodont, is a sigmodontine rodent from South America.
Oligoryzomys nigripes, also known as the black-footed colilargo or the black-footed pygmy rice rat, is a rodent in the genus Oligoryzomys of family Cricetidae. Oligoryzomys nigripes is a species that has been further divided into different sister taxa throughout history. It is found in different countries in South America. It is a large species with long ears, dark yellow to dark brown upperparts, sharply delimited from the whitish underparts, and often a pink girdle on the chest. This species of rat spends much of its life among the trees. The karyotype is 2n = 62, FNa = 78–82.
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.
Juliomys rimofrons, also known as the cleft-headed juliomys, is a South American rodent species in the family Cricetidae. It is found in southern Brazil. The species is arboreal and lives in montane forests. It is threatened because of the small size and fragmentation of its current range. It's karyotype has 2n = 20, FN = 34.
Rhipidomys is a genus of rodents in the family Cricetidae, The following 25 species of climbing mouse species are currently recognised:
Oligoryzomys magellanicus, also known as the Patagonian colilargo and the Magellanic pygmy rice rat, is a species of rodent in the genus Oligoryzomys of the family Cricetidae. It is found in the southernmost parts of Argentina and Chile, including Tierra del Fuego and other outlying islands. Its karyotype has 2n = 54 and FNa = 66.
The blackish deer mouse is a species of rodent in the family Cricetidae found only in Mexico, and is relatively poorly studied.
The nimble-footed mouse is a species of rodent in the family Cricetidae. It is found only in Mexico.
The Mexican deer mouse is a species of forest-dwelling rodent in the family Cricetidae. It is found in southern Mexico and throughout much of Central America.
The tawny deer mouse or marsh mouse is a species of rodent in the family Cricetidae. It is found only in Mexico.
Thomasomys is a genus of rodents in the family Cricetidae, named after British zoologist Oldfield Thomas. Nuclear DNA sequence analysis has indicated that it is a sister taxon to Rhagomys. It contains the following species:
Oligoryzomys moojeni is a species of rodent from South America in the genus Oligoryzomys of family Cricetidae. It is known only from central Brazil, where it is found in the cerrado and gallery forests. It is named after twentieth-century Brazilian zoologist João Moojen. Its karyotype has 2n = 70 and FNa = 84.
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.
Cerradomys maracajuensis, also known as the Maracaju oryzomys, is a rodent species from South America. It is terrestrial and is found in gallery forests in Bolivia, Paraguay and nearby Brazil and Peru. It was first discovered near the Brazilian city of Maracaju.
Juliomys anoblepas is a rodent in the genus Juliomys of the subfamily Sigmodontinae known from a single broken skull. The specimen was collected by Peter Wilhelm Lund in the caves of Lagoa Santa, Minas Gerais, Brazil, in the first half of the 19th century and described by Herluf Winge in 1888 as Calomys anoblepas. The species remained unstudied and its affinities unclear until 2011, when it was recognized as a member of the genus Juliomys, which includes three other species from southern Brazil and nearby Argentina and Paraguay. J. anoblepas is probably a separate extinct species of the genus, which is no longer found at Lagoa Santa.
Delomys is a genus of South American rodents of family Cricetidae. Three species are known, all found in the Atlantic Forest of Argentina and Brazil. They are as follows:
Rhagomys is a genus of South American rodents in the tribe Thomasomyini of the family Cricetidae. Two species separated by about 3100 km are known, from southeast Peru and Bolivia east of the Andes, and in the Atlantic Forest of southeast Brazil. An undetermined species of Rhagomys has also been reported from Mato Grosso in central Brazil. The species are as follows:
