Oryzomys is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat (O. palustris) of the United States and O. couesi of Mexico and Central America—are widespread; the six others have more restricted distributions. The species have had eventful taxonomic histories, and most species were at one time included in the marsh rice rat; additional species may be recognized in the future. The name Oryzomys was established in 1857 by Spencer Fullerton Baird for the marsh rice rat and was soon applied to over a hundred species of American rodents. Subsequently, the genus gradually became more narrowly defined until its current contents were established in 2006, when ten new genera were established for species previously placed in Oryzomys.
Oligoryzomys chacoensis, also known as the Chacoan colilargo or Chacoan pygmy rice rat, is a rodent species from South America. It is found in the Gran Chaco region of southeastern Bolivia, southwestern Brazil, Paraguay, and northeastern Argentina. Its karyotype has 2n = 58 and FNa = 74.
Oligoryzomys flavescens, also known as the flavescent colilargo or yellow pygmy rice rat is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found in southern South America, occurring in southern Brazil, Paraguay, Uruguay, and northeastern Argentina. Its karyotype has 2n = 64-66 and FNa = 66-70.
Oligoryzomys fulvescens, also known as the fulvous colilargo, fulvous pygmy rice rat, or northern pygmy rice rat, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found from southern Mexico through Central America into South America, where it occurs south into Peru and Brazil, and includes numerous synonyms, including the type species of the genus, Oryzomys navus Bangs, 1899. The taxonomy of this species is unresolved, and it may be found to contain more than one species. Its karyotype has 2n = 54-60 and FNa = 68–74.
Oligoryzomys microtis, also known as the small-eared colilargo or small-eared pygmy rice rat, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found in western Brazil, eastern Peru, Bolivia, and northern Paraguay.
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.
Oligoryzomys stramineus, also known as the straw-colored colilargo or straw-colored pygmy rice rat, is a species of rodent in the genus Oligoryzomys of the family Cricetidae. It occurs only in the cerrado and caatinga ecoregions of northeastern Brazil. Its karyotype has 2n = 52 and FNa = 68-70.
Oligoryzomys is a genus of rodents in the tribe Oryzomyini of family Cricetidae. Many species are known as pygmy rice rats or colilargos. The genus is found from Mexico to Tierra del Fuego and includes approximately 17 species.
Abrothrix andina, also known as the Andean Altiplano mouse or Andean akodont, is a species of rodent in the genus Abrothrix of family Cricetidae. It is found in the Altiplano habitat of the Andes from central Peru through Bolivia, south to Argentina and Chile.
Oligoryzomys arenalis, also known as the sandy colilargo or sandy pygmy rice rat, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found in the Andes of Peru at 400 to 2850 m altitude, but may include more than one species.
Oligoryzomys destructor, also known as Tschudi's colilargo or the destructive pygmy rice rat, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found along the eastern Andes from southern Colombia, through Ecuador, Peru, and Bolivia into northern Argentina. Its karyotype has 2n = 60 and FNa = 76.
Oligoryzomys griseolus, also known as the grizzled colilargo or the grayish pygmy rice rat, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found in the Andes of Venezuela and nearby Colombia. Its karyotype has 2n = 62 and FNa = 74–76.
Oligoryzomys longicaudatus, also known as the long-tailed colilargo or long-tailed pygmy rice rat, is a species of rodent in the genus Oligoryzomys of the family Cricetidae. It is found in the southern Andes of Chile and Argentina, with an outlying population in eastern Argentina. As a common species with a wide range and a stable population, the International Union for Conservation of Nature has rated this rodent as being of "least concern".
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.
Oligoryzomys vegetus, also known as the sprightly colilargo or sprightly pygmy rice rat, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found only in the mountains of Costa Rica and western Panama.
Oligoryzomys victus, also known as the St. Vincent colilargo or St. Vincent pygmy rice rat, is a species of rodent in the genus Oligoryzomys of the oryzomyine tribe. Only one specimen is known, which was collected on Saint Vincent in the Lesser Antilles in about 1892, and it is now presumed extinct.
Nephelomys albigularis, also known as the white-throated oryzomys or Tomes's rice rat, is a species of rodent in the genus Nephelomys of family Cricetidae. Described in 1860, it was the first Nephelomys species to be discovered. It was originally described in the defunct genus Hesperomys as Hesperomys albigularis and considered related to the much smaller H. longicaudatus. By 1894, it was placed in Oryzomys, as Oryzomys albigularis, and associated with what is now Nephelomys meridensis. In the early 1960s, the scope of the species was considerably expanded to include most of the species that are now in Nephelomys, as well as a single name, boliviae, that is currently a synonym of Euryoryzomys nitidus. From 1976 on, several of these were reinstated as separate species.
Oligoryzomys fornesi, also known as Fornes' colilargo, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found from northeastern Brazil via Paraguay into northeastern Argentina. Its karyotype has 2n = 62 and FNa = 64.
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.
Oligoryzomys rupestris is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is known only from eastern Brazil, where it has been found in several localities in the campos rupestres montane savanna ecoregion. This is a small Oligoryzomys species with a gray head, a yellow-brown back and gray belly and tail. Of the two karyotypic forms described by Silva & Yonenaga-Yassuda in 1998, species 1 is probably identical to O. rupestris, while the other is closely related. Its karyotype has 2n = 46 and FNa = 52.
