The New World rats and mice are a group of related rodents found in North and South America. They are extremely diverse in appearance and ecology, ranging in from the tiny Baiomys to the large Kunsia. They represent one of the few examples of muroid rodents in North America, and the only example of muroid rodents to have made it into South America.
Akodon is a genus consisting of South American grass mice. They mostly occur south of the Amazon Basin and along the Andes north to Venezuela, but are absent from much of the basin itself, the far south of the continent, and the lowlands west of the Andes. Akodon is one of the most species-rich genera of Neotropical rodents. Species of Akodon are known to inhabit a variety of habitats from tropical and tropical moist forests to altiplano and desert. Fossils are known from the late Pliocene onwards.
Bibimys is a genus of new world rats. Commonly known as the crimson-nosed rats, there are three species:
Oxymycterus is the genus of hocicudos. They are rat-like animals endemic to South America. As of April 2019 it included 16 species.
The genus Eligmodontia consists of five or six species of South American sigmodontine mice restricted to Bolivia, Chile, and Argentina. Species of Eligmodontia occur along the eastern side of the Andes Mountains, in Patagonia, and in the Chaco thorn forest of South America. They can be found in arid and semiarid habitats and in both high and low elevation areas. These rodents are commonly known as gerbil mice or by their local name lauchas. Sometimes they are also called silky desert mice, highland desert mice or silky-footed mice. The closest living relatives are probably the chaco mice (Andalgalomys), the leaf-eared mice, and Salinomys.
The cursor grass mouse or cursorial akodont, is a sigmodontine rodent from South America.
Brucepattersonius griserufescens, also known as the gray-bellied akodont or grey-bellied brucie, is a rodent in the cricetid genus Brucepattersonius from southeastern Brazil, specifically the states of Minas Gerais, Espírito Santo and Rio de Janeiro between 1,300 and 2,700 meters. It was one of four species of Brucepattersonius described by Hershkovitz in 1998; another, Brucepattersonius albinasus, also known as the white-nosed akodont or white-nosed brucie, was later argued to be the same as B. griserufescens, though further work is needed to confirm this. It is threatened by habitat loss but is also protected by Caparaó National Park.
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.
Lundomys molitor, also known as Lund's amphibious rat or the greater marsh rat, is a semiaquatic rat species from southeastern South America.
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.
Vesper mice are rodents belonging to a genus Calomys. They are widely distributed in South America. Some species are notable as the vectors of Argentinian hemorrhagic fever and Bolivian hemorrhagic fever.
Akodon spegazzinii, also known as Spegazzini's akodont or Spegazzini's grass mouse, is a rodent in the genus Akodon found in northwestern Argentina. It occurs in grassland and forest at 400 to 3,500 m above sea level. After the species was first named in 1897, several other names were given to various populations now included in A. spegazzinii. They are now all recognized as part of a single, widespread and variable species. Akodon spegazzinii is related to Akodon boliviensis and other members of the A. boliviensis species group. It reproduces year-round. Because it is widely distributed and common, Akodon spegazzinii is listed as "least concern" on the IUCN Red List.
Irenomys tarsalis, also known as the Chilean climbing mouse, Chilean tree mouse, or long-footed irenomys, is a rodent found in Chile, from about 36° to 46°S, and in adjacent Argentina, mainly in forests. It is a large, long-tailed, soft-furred mouse characterized by grooved upper incisors and specialized molars with transverse ridges, divided by deep valleys, which are connected by a transverse ridge along the midline of the molars.
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.
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 its own genus, Mindomys, but its relationships remain obscure; some evidence supports a placement near Oecomys or as a basal member of Oryzomyini.
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.
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.
In anatomy, posterolateral palatal pits are gaps at the sides of the back of the bony palate, near the last molars. Posterolateral palatal pits are present, in various degrees of development, in several members of the rodent family Cricetidae. Many members of the family lack them or have only simple pits, but Arvicolinae and Oryzomyini have more highly developed posterolateral palatal pits. Posterolateral palatal pits are also present in some other rodents, including Glis, Jaculus, Hystrix, Abrocoma, Ctenomys, Chinchilla, and Lagidium.
Abrotrichini, also known as the Andean clade or southern Andean clade, is a tribe of rodents in the subfamily Sigmodontinae. It includes about fifteen species in four genera, distributed in South America from southern Peru to southernmost South America, including the Patagonian steppes. The earliest known fossils are from the Pliocene of Argentina.
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:
