The New World rats and mice are a group of related rodents found in

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. They are extremely diverse in appearance and ecology, ranging from the tiny ''

Baiomys ''Baiomys'', the New World pygmy mice, is a genus of rodents in the family Cricetidae. Together with '' Scotinomys'', it forms the tribe Baiomyini. It contains the smallest rodents in North America. It currently contains three extant species: ...

'' to the large '' Kunsia''. They represent one of the few examples of

muroid rodent The Muroidea are a large superfamily of rodents, including mice, rats, voles, hamsters, lemmings, gerbils, and many other relatives. Although the Muroidea originated in Eurasia, they occupy a vast variety of habitats on every continent except A ...

s (along with the

voles Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molar (tooth), molars (high-crowned with angular cusps i ...

) in North America, and the only example of muroid rodents to have made it into South America. The New World rats and mice are often considered part of a single subfamily,

Sigmodontinae 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 ...

, but the recent trend among muroid taxonomists is to recognize three separate subfamilies. This strategy better represents the extreme diversity of species numbers and ecological types. Some

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies have suggested that the New World rats and mice are not a

monophyletic group In biology, a clade (), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy ...

, but this is yet to be confirmed. Their closest relatives are clearly the

hamster Hamsters are rodents (order Rodentia) belonging to the subfamily Cricetinae, which contains 19 species classified in seven genera. They have become established as popular small pets. The best-known species of hamster is the golden or Syrian ...

s and

vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...

s. The New World rats and mice are divided into 3 subfamilies, 12 tribes, and 84 genera.

Classification

*Family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At over 870 species, it is either the largest or second-largest family ...

s, and New World rats and mice **Subfamily

Tylomyinae The subfamily Tylomyinae consists of several species of New World rats and mice including the vesper and climbing rats. They are not as well known as their relatives in the subfamilies Sigmodontinae and Neotominae. Many authorities place all th ...

***'' Otonyctomys'' ***''

Nyctomys Sumichrast's vesper rat (''Nyctomys sumichrasti'') is a rodent of the family Cricetidae found from southern Mexico to Panama. It is named for François Sumichrast, the collector of the first specimen, and its closest relative is probably Hatt's ...

'' ***'' Tylomys'' ***'' Ototylomys'' **Subfamily

Neotominae The Neotominae are a subfamily of the family Cricetidae. They consist of four tribes, 16 genera, and many species of New World rats and mice, predominantly found in North America. Among them are the well-known deer mice, packrats, and grasshopp ...

***Tribe

Baiomyini Baiomyini is a tribe of rodents in the subfamily Neotominae occurring from the southern United States to Panama. It includes the genera ''Baiomys'' and ''Scotinomys ''Scotinomys'' is a genus of rodent, the singing mice, in the family Cricetida ...

****''

'' ****''

Scotinomys ''Scotinomys'' is a genus of rodent, the singing mice, in the family Cricetidae. Together with ''Baiomys ''Baiomys'', the New World pygmy mice, is a genus of rodents in the family Cricetidae. Together with '' Scotinomys'', it forms the tribe ...

'' ***Tribe

Neotomini The Neotominae are a subfamily of the family Cricetidae. They consist of four tribes, 16 genera, and many species of New World rats and mice, predominantly found in North America. Among them are the well-known deer mice, packrats, and grasshopp ...

****''

Neotoma A pack rat or packrat, also called a woodrat or trade rat, are any species in the North and Central American rodent genus ''Neotoma''. Pack rats have a rat-like appearance, with long tails, large ears, and large, black eyes. Pack rats are notice ...

'' ****''

Xenomys The Magdalena rat (''Xenomys nelsoni'') is a species of rodent in the family Cricetidae which is found only in a small region of western Mexico. It is the only species in the genus ''Xenomys''. The common name comes from the village where the ...

'' ****''

Hodomys Allen's woodrat (''Hodomys alleni'') is a species of rodent in the family Cricetidae. It is the only species in the genus ''Hodomys''. Distribution This woodrat species is endemic to Mexico. It is native from southern Sinaloa to Oaxaca states. ...

'' ****'' Nelsonia'' ***Tribe

Ochrotomyini The golden mouse (''Ochrotomys nuttalli'') is a species of New World mouse. It is usually 5–8 inches (12–25 cm) in body length, and has a soft pelage that ranges from golden-brownish to burnt orange in color. The genus name comes ...

****''

Ochrotomys The golden mouse (''Ochrotomys nuttalli'') is a species of New World mouse. It is usually 5–8 inches (12–25 cm) in body length, and has a soft pelage that ranges from golden-brownish to burnt orange in color. The genus name comes ...

'' ***Tribe

Reithrodontomyini The Neotominae are a subfamily of the family Cricetidae. They consist of four tribes, 16 genera, and many species of New World rats and mice, predominantly found in North America. Among them are the well-known deer mice, packrats, and grasshop ...

****''

Peromyscus ''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, ''M ...

'' ****''

Reithrodontomys ''Reithrodontomys'' is the genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#I ...

'' ****''

Onychomys Grasshopper mice are rodents of the genus ''Onychomys'', occurring in North America. They feed on insects and other arthropods. Biology The three species in this genus of New World mice are only distantly related to the common house mouse, ''Mu ...

'' ****'' Neotomodon'' ****'' Podomys'' ****''

Isthmomys ''Isthmomys'' is a genus of rodent in the family Cricetidae, belonging to the tribe Reithrodontomyini. Species are: *Yellow isthmus rat (''Isthmomys flavidus'') *Mount Pirri isthmus rat The Mount Pirri isthmus rat (''Isthmomys pirrensis'') is ...

'' ****'' Megadontomys'' ****'' Habromys'' ****'' Osgoodomys'' **Subfamily

***'' Rhagomys'' ''

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'' ***Tribe

Oryzomyini Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera,Weksler et al., 2006, table 1 distributed from the eastern United States to the southernmost parts of S ...

****''

Oryzomys ''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 ...

'' ****'' Nesoryzomys'' ****'' Melanomys'' ****'' Sigmodontomys'' ****'' Nectomys'' ****'' Amphinectomys'' ****''

Oligoryzomys ''Oligoryzomys'' is a genus of rodents in the tribe Oryzomyini of family Cricetidae. Many species are known as pygmy rice rats or colilargos.Musser and Carleton, 2005 The genus is found from Mexico to Tierra del Fuego and includes approximately 1 ...

'' ****''

Neacomys The genus ''Neacomys'', also known as bristly mice because of their spiny fur, includes several species of rodents in the tribe Oryzomyini of family Cricetidae. It is most closely related to ''Oligoryzomys'', '' Oreoryzomys'', and '' Microryzomys ...

'' ****''

Zygodontomys ''Zygodontomys'' is a genus of rodent in the tribe Oryzomyini of the family Cricetidae. Its closest relative may be '' Scolomys''. It ranges from Central America east to the Guianas The Guianas, also spelled Guyanas or Guayanas, are a geog ...

'' ****''

Lundomys ''Lundomys molitor'', also known as Lund's amphibious ratMusser and Carleton, 2005, p. 1124 or the greater marsh rat, is a semiaquatic rat species from southeastern South America. Its distribution is now restricted to Uruguay and nearby Ri ...

'' ****''

Holochilus ''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 ...

'' ****''

Pseudoryzomys ''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 List of mammals of South America, South America. It is found in lowland Tropical and sub ...

'' ****'' Microakodontomys'' ****'' Oecomys'' ****'' Microryzomys'' ****'' Scolomys'' ***Tribe Thomasomyini ****'' Chilomys'' ****'' Abrawayaomys'' ****'' Delomys'' ****'' Thomasomys'' ****'' Wilfredomys'' ****'' Aepomys'' ****'' Phaenomys'' ****'' Rhipidomys'' ***Tribe Wiedomyini ****'' Wiedomys'' ***Tribe

Akodontini Akodontini is the second most speciose rodent tribe of the subfamily Sigmodontinae. It includes at least 106 living species in 19 genera and is distributed mainly in the southern half of South America, with only two genera extending into Guyana (' ...

****''

Akodon ''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 ...

'' ****''

Bibimys ''Bibimys'' is a genus of new world rats. Commonly known as the crimson-nosed rats, there are three species: *'' Bibimys chacoensis'' - Chaco crimson-nosed rat - found in north-east Argentina and Paraguay *'' Bibimys labiosus'' - Large-lipped c ...

'' ****'' Bolomys'' ****'' Podoxymys'' ****''

Thalpomys ''Thalpomys'' is a genus of South American rodents in the tribe Akodontini of family Cricetidae. Two species are known, both found in the cerrado tropical savanna ecoregion of central Brazil Brazil, officially the Federative Republic of B ...

'' ****'' Abrothrix'' ****'' Chroeomys'' ****'' Chelemys'' ****'' Notiomys'' ****'' Pearsonomys'' ****'' Geoxus'' ****'' Blarinomys'' ****'' Juscelinomys'' ****'' Oxymycterus'' ****'' Lenoxus'' ****'' Brucepattersonius'' ****'' Scapteromys'' ****'' Kunsia'' ****''

'' ***Tribe Phyllotini ****''

Calomys Vesper mice are rodents belonging to the genus ''Calomys''. They are widely distributed in South America. Some species are notable as the Vector (epidemiology), vectors of Argentinian hemorrhagic fever and Bolivian hemorrhagic fever. The genus w ...

'' ****'' Eligmodontia'' ****'' Andalgalomys'' ****'' Graomys'' ****'' Salinomys'' ****''

Phyllotis ''Phyllotis'' is a genus of rodent in the family Cricetidae. These mice are commonly confused with ''Auliscomys, Graomys'' and ''Loxodontomys.'' ''.'' In order to tell these genera apart, one must look at the tail. Species in the genus ''Phyllo ...

'' ****'' Loxodontomys'' ****'' Auliscomys'' ****'' Galenomys'' ****'' Chinchillula'' ****'' Punomys'' ****'' Andinomys'' ****'' Irenomys'' ****''

Euneomys ''Euneomys'' is a genus of rodents in the family Cricetidae. It contains the following species: * Patagonian chinchilla mouse (''Euneomys chinchilloides'') * Burrowing chinchilla mouse (''Euneomys fossor'') * Biting chinchilla mouse (''Euneomys m ...

'' ****'' Neotomys'' ****'' Reithrodon'' ***Tribe Sigmodontini ****'' Sigmodon'' ***Tribe

Ichthyomyini Ichthyomyini is a tribe of New World rats and mice in the subfamily Sigmodontinae. The species within this tribe share the characteristics of all being carnivorous semiaquatic rodents. The following genera are recognized in this tribe: * Subtribe ...

****'' Neusticomys'' ****''

Rheomys ''Rheomys'' is a genus of Mexican and Central American semiaquatic rodents in the family Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrat ...

'' ****''

Anotomys The aquatic rat, Ecuador fish-eating rat, fish-eating rat or Ecuadoran ichthyomyine (''Anotomys leander'') is a South American species of semiaquatic rodent in the family Cricetidae. It is the monotypic taxon, only species in the genus ''Anotomy ...

'' ****'' Chibchanomys'' ****'' Ichthyomys''

References

*Centers for Disease Control, 2002.
"Hantavirus Pulmonary Syndrome — United States: Updated Recommendations for Risk Reduction."
''Mortality and Morbidity Weekly Report'', 51:09. Retrieved on 2007-07-13. *D'Elia, G. 2003. Phylogenetics of Sigmodontinae (Rodentia, Muroidea, Cricetidae), with special reference to the akodont group, and with additional comments on historical biogeography. Cladistics 19:307-323. *Mares, M. A., and J. K. Braun. 2000. Graomys, the genus that ate South America: A reply to Steppan and Sullivan. Journal of Mammalogy 81:271-276. *McKenna, M. C. and S. K. Bell. 1997.

Classification Classification is the activity of assigning objects to some pre-existing classes or categories. This is distinct from the task of establishing the classes themselves (for example through cluster analysis). Examples include diagnostic tests, identif ...

Mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s above the

Species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

Level. Columbia University Press, New York. *Steppan, S. J., R. A. Adkins, and J. Anderson. 2004.

Phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

and divergence date estimates of rapid radiations in

muroid The Muroidea are a large superfamily of rodents, including mice, rats, voles, hamsters, lemmings, gerbils, and many other relatives. Although the Muroidea originated in Eurasia, they occupy a vast variety of habitats on every continent except ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

s based on multiple nuclear

genes In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

. Systematic Biology, 53:533-553. {{DEFAULTSORT:New World Rats And Mice Cricetidae Paraphyletic groups