The greater guinea pig is a species of rodent found in the coastal strip of Brazil and Uruguay, where it lives in moist grassland and marshes.
The long-tailed spiny rat is a spiny rat species found in Bolivia, Brazil and Paraguay.
Ruschi's rat or Ruschi's spiny mouse is a rodent species found in Argentina and Brazil. Some cranial features suggest it may be an archaic relative of the paramo Oldfield mouse. The upper parts are greyish yellow with a darker head and yellowish-white underparts. Fine hairs are mixed with flattened and grooved spines that are most numerous on the back.
Euryoryzomys nitidus, also known as the elegant oryzomys or elegant rice rat, is a rodent species in the family Cricetidae. Previously it was known as Oryzomys nitidus, but it is not closely related to Oryzomys as that genus is now constructed. Its range includes Bolivia, Brazil and Peru to the east of the Andes, in lowland tropical rainforest as well as forest in the eastern foothills of the mountains, at elevations from 50 to 2,000 m.
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.
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.
The Amazonian marsh rat, also known as the common marsh rat, or simply the marsh rat, is a rodent species from South America.
Lundomys molitor, also known as Lund's amphibious rat or the greater marsh rat, is a semiaquatic rat species from southeastern South America.
Waterhouse's swamp rat is a semiaquatic rodent species from South America. It is found in southern Brazil, Uruguay and northern Argentina, where it lives in freshwater and salt marshes, as well as open grassland of the pampas. Its karyotype has 2n = 24, substantially lower than its closest relative S. aquaticus with 2n = 32.
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.
Holochilus chacarius, also known as the Chacoan marsh rat or Chaco marsh rat, is a semiaquatic rodent species in the family Cricetidae. It is found in Argentina and Paraguay within the Gran Chaco.
Holochilus is a genus of semiaquatic rodents in the tribe Oryzomyini of family Cricetidae, sometimes called marsh rats. It contains five living species, H. brasiliensis, H. chacarius, H. nanus, H. oxe, and H. sciureus, which are widely distributed in South America east of the Andes. A fourth species from the Pleistocene of Bolivia was formerly classified as H. primigenus, but is now placed in the genus Reigomys.
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.
Noronhomys vespuccii, also known as Vespucci's rodent, is an extinct rat species from the islands of Fernando de Noronha off northeastern Brazil. Italian explorer Amerigo Vespucci may have seen it on a visit to Fernando de Noronha in 1503, but it subsequently became extinct, perhaps because of the exotic rats and mice introduced by the first explorers of the island. Numerous but fragmentary fossil remains of the animal, of uncertain but probably Holocene age, were discovered in 1973 and described in 1999.
The Argentine swamp rat is a semiaquatic rodent species from South America. It is found in northeastern Argentina and Paraguay, where it lives in freshwater marshes and along the southern coast of the Río de la Plata estuary, as well as in woodland. It is characterized by having stiff hairs on its otherwise naked tail, which are believed to help the animal swim. S. aquaticus is similar in build to members of the genus Rattus. "[It] has a relatively larger head, a stouter body, larger feet, and a relatively longer tail." The pelage along its back is "long and glossy" varying from brown to dark brown. It can have a grayish wash in some individuals. "The sides have a yellowish cast." The pelage in the abdominal region is typically an off white color. The forefeet are large for use in swimming and digging. All digits, including the pollex are equipped with a claw. Its karyotype has 2n = 32.
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.
Reigomys primigenus is an extinct oryzomyine rodent known from Pleistocene deposits in Tarija Department, southeastern Bolivia. It is known from a number of isolated jaws and molars which show that its molars were almost identical to those of the living Lundomys. On the other hand, the animal possesses a number of derived traits of the palate which document a closer relationship to living Holochilus, the genus of South American marsh rats, and for this reason it was placed in the genus Holochilus when it was first described in 1996. The subsequent discoveries of Noronhomys and Carletonomys, which may be more closely related to extant Holochilus than H. primigenus is, have cast its placement in Holochilus into doubt, and it was ultimately made the type species of a separate genus, Reigomys.
In mammals, ungual tufts are tufts of hairs at the base of claws of the forefeet and hindfeet. Their presence has been used as a character in cladistic studies of the Cricetidae, a large family of rodents.
Gigantolaelaps mattogrossensis is a mite from the Americas. It has been found on the marsh rice rat, hispid cotton rat, black rat, brown rat, and white-footed mouse in the United States. In Venezuela, it has been recorded from Holochilus brasiliensis, Sigmodon hirsutus, and Marmosa robinsoni. In Argentina, it has been found on Scapteromys aquaticus, Oligoryzomys flavescens, and Holochilus brasiliensis. The North American form was first described as a separate species, Gigantolaelaps cricetidarum, and is still occasionally considered as such.
Scapteromys is a genus of South American rodents in the tribe Akodontini of family Cricetidae. Three species are known, found in northern Argentina, southern Brazil, Paraguay and Uruguay. They are as follows:
