Oryzomys nelsoni is an extinct rodent of María Madre Island, Nayarit, Mexico. Within the genus Oryzomys of the family Cricetidae, it may have been most closely related to the mainland species O. albiventer. Since its first description in 1898, most authors have regarded it as a distinct species, but it has also been classified as a mere subspecies of the marsh rice rat (O. palustris).
Oryzomys couesi, also known as Coues's rice rat, is a semiaquatic rodent in the family Cricetidae occurring from southernmost Texas through Mexico and Central America into northwestern Colombia. It is usually found in wet habitats, such as marshes, but also lives in drier forests and shrublands. Weighing about 43 to 82 g, O. couesi is a medium-sized to large rat. The coarse fur is buff to reddish above and white to buff below. The hindfeet show some specializations for life in the water, such as reduced ungual tufts of hair around the digits. It has 56 chromosomes. There is much geographic variation in size, proportions, color, and skull features. Oryzomys couesi is active during the night and builds nests of vegetation that are suspended among reeds about 1 m (3.3 ft) above the ground. It is an excellent swimmer and dives well, but can also climb in vegetation. An omnivore, it eats both plant and animal food, including seeds and insects. It breeds throughout the year; females give birth to about four young after a pregnancy of 21 to 28 days. The species may be infected by several different parasites and by two hantaviruses.
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.
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.
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.
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.
Transandinomys bolivaris, also known as the long-whiskered rice rat, is a rodent in the family Cricetidae. It is found in humid forest from northeastern Honduras to western Ecuador, up to 1,800 m (5,900 ft) above sea level. Since it was first described in 1901 from Ecuador, six scientific names have been introduced for it, but their common identity was not documented until 1998 and the species has long been known under the name Oryzomys bombycinus, described from Panama in 1912. The name Oryzomys bolivaris was used before it was moved to the new genus Transandinomys with Transandinomys talamancae in 2006.
Oryzomys dimidiatus, also known as the Nicaraguan oryzomys, Thomas's rice rat, or the Nicaraguan rice rat, is a rodent in the family Cricetidae. It is known from only three specimens, all collected in southeastern Nicaragua since 1904. Placed in Nectomys upon its discovery, it was later classified in its own subgenus of Oryzomys and finally recognized as closely related to other species now placed in Oryzomys, including the marsh rice rat and Coues' rice rat, which occurs in the same region.
Oryzomys gorgasi, also known as Gorgas's oryzomys or Gorgas's rice rat, is a rodent in the genus Oryzomys of family Cricetidae. First recorded in 1967, it is known from only a few localities, including a freshwater swamp in the lowlands of northwestern Colombia and a mangrove islet in northwestern Venezuela. It reportedly formerly occurred on the island of Curaçao off northwestern Venezuela; this extinct population has been described as a separate species, Oryzomys curasoae, but does not differ morphologically from mainland populations.
Mindomys hammondi, also known as Hammond's rice rat or Hammond's oryzomys, is an endangered species of rodent in the tribe Oryzomyini of family Cricetidae. Formerly considered to be related with Nectomys, Sigmodontomys, Megalomys, or Oryzomys, it is now placed in then genus Mindomys, but its relationships remain obscure; some evidence supports a placement near Oecomys or as a basal member of Oryzomyini.
Nephelomys levipes, also known as the nimble-footed oryzomys or light-footed rice rat, is a species of rodent in the genus Nephelomys of family Cricetidae. It is found on the eastern slope of the Andes from southeastern Peru into west-central Bolivia in cloud forest at elevations from 1,800 to 3,200 metres. It occurs in the same general area as its congener N. keaysi, but at higher altitudes.
The marsh rice rat is a semiaquatic North American rodent in the family Cricetidae. It usually occurs in wetland habitats, such as swamps and salt marshes. It is found mostly in the eastern and southern United States, from New Jersey and Kansas south to Florida and northeasternmost Tamaulipas, Mexico; its range previously extended further west and north, where it may have been a commensal in corn-cultivating communities. Weighing about 40 to 80 g, the marsh rice rat is a medium-sized rodent that resembles the common black and brown rat. The upperparts are generally gray-brown, but are reddish in many Florida populations. The feet show several specializations for life in the water. The skull is large and flattened, and is short at the front.
Eremoryzomys polius, also known as the gray rice rat or the Marañon oryzomys, is a rodent species in the tribe Oryzomyini of the family Cricetidae. Discovered in 1912 and first described in 1913 by Wilfred Osgood, it was originally placed in Oryzomys and named Oryzomys polius. In 2006, a cladistic analysis found that it was not closely related to Oryzomys in the strict sense or to any other oryzomyine then known, so that it is now placed in its own genus, Eremoryzomys. The Brazilian genus Drymoreomys, named in 2011, is probably the closest relative of Eremoryzomys. Eremoryzomys has a limited distribution in the dry upper valley of the Marañón River in central Peru, but may yet contain more than one species.
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.
Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera, distributed from the eastern United States to the southernmost parts of South America, including many offshore islands. It is part of the clade Oryzomyalia, which includes most of the South American Sigmodontinae.
Oryzomys antillarum, also known as the Jamaican rice rat, is an extinct rodent of Jamaica. A member of the genus Oryzomys within the family Cricetidae, it is similar to O. couesi of mainland Central America, from where it may have dispersed to its island during the last glacial period. O. antillarum is common in subfossil cave faunas and is also known from three specimens collected live in the 19th century. Some historical records of Jamaican rats may pertain to it. The species probably became extinct late in the 19th century, perhaps due to the introduction of the small Indian mongoose, competition with introduced rodents such as the brown rat, and habitat destruction.
Carletonomys cailoi is an extinct rodent from the Pleistocene (Ensenadan) of Buenos Aires Province, Argentina. Although known only from a single maxilla with the first molar, its features are so distinctive that it is placed in its own genus, Carletonomys. Discovered in 1998 and formally described in 2008, it is part of a well-defined group of oryzomyine rodents that also includes Holochilus, Noronhomys, Lundomys, and Pseudoryzomys. This group is characterized by progressive semiaquatic specializations and a reduction in the complexity of molar morphology.
Megalomys audreyae, known as the Barbudan (?) muskrat or the Barbuda giant rice rat, is an extinct oryzomyine rodent from Barbuda in the Lesser Antilles. Described on the basis of a single mandible with the first molar missing and an isolated upper incisor, both of uncertain but Quaternary age, it is one of the smaller members of the genus Megalomys. Little is known about the animal, and its provenance and distinction from "Ekbletomys hypenemus", an even larger extinct oryzomyine that also occurred on Barbuda, have been called into question. The toothrow in the lower jaw has a length of 8.7 mm at the alveoli. The third molar is relatively narrow and both the second and third molars have a wide valley between their outer cusps.
Oryzomys albiventer is a rodent in the genus Oryzomys of family Cricetidae from interior western Mexico, in the states of Jalisco, Guanajuato, and Michoacán. First described in 1901 as a separate species, it was later lumped under O. couesi and the marsh rice rat (O. palustris) until it was reinstated as a species in 2009. It differs from neighboring Oryzomys populations in size and measurements and is a large, brightly colored species with a long tail and robust skull and molars. Its range has been much impacted by agricultural development, but isolated populations are thought to persist.
