''Oligoryzomys nigripes'', also known as the black-footed colilargo or the black-footed pygmy rice rat, is a

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

in the genus ''

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 ...

'' of 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 almost 608 species, it is the second-largest family of mammals, and h ...

. 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.Weksler, M. & Bonvicino, C.R. 2005. Taxonomy of pygmy rice rats genus ''Oligoryzomys'' Bangs, 1900 (Rodentia, Sigmodontinae) of the Brazilian Cerrado, with the description of two new species. Arquivos do Museu Nacional 63(1):119. 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.

Synonym species

Two other species, '' Oligoryzomys delticola'' (also known as the delta pygmy rice rat or the large colilargo) and '' Oligoryzomys eliurus'' (also known as the Brazilian pygmy rice rat or the Brazilian colilargo) have been recognized as synonyms of ''O. nigripes'' since 2005; they cannot be distinguished on the basis of

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

, karyotype, or

morphometrics Morphometrics (from Greek μορϕή ''morphe'', "shape, form", and -μετρία ''metria'', "measurement") or morphometry refers to the quantitative analysis of ''form'', a concept that encompasses size and shape. Morphometric analyses are co ...

Location

''Oligoryzomys nigripes'' is found from

Pernambuco Pernambuco () is a States of Brazil, state of Brazil, located in the Northeast Region, Brazil, Northeast region of the country. With an estimated population of 9.6 million people as of 2020, making it List of Brazilian states by population, sev ...

in northeastern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

through the Atlantic Forest and

Cerrado The ''Cerrado'' (, ) is a vast ecoregion of tropical savanna in eastern Brazil, particularly in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Minas Gerais, and the Federal District. The core areas of the Cerrado biome are the ...

into

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

, and

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, where it occurs in the provinces of Chaco,

Misiones Misiones (, ''Missions'') is one of the 23 provinces of Argentina, located in the northeastern corner of the country in the Mesopotamia region. It is surrounded by Paraguay to the northwest, Brazil to the north, east and south, and Corrientes P ...

, and

Buenos Aires Buenos Aires ( or ; ), officially the Autonomous City of Buenos Aires ( es, link=no, Ciudad Autónoma de Buenos Aires), is the capital and primate city of Argentina. The city is located on the western shore of the Río de la Plata, on South ...

Morphology

The

pelage Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an insulating blanket ...

colors for this species resemble brown, dark yellow, and grey. This species of ''Oligoryzomys'' have small bodies and long tails. The totaled head plus body length of the

model species A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

for ''O. nigripes'' is 9 cm. The tail length for the model species for ''O. nigripes'' is 10.5 cm. The weight of the animal ranges from 26.32 grams to 33.3 grams. The eyes of this species are rounded and jet black.

Behavior

''Oligoryzomys nigripes'' is a nocturnal species of

. They live entirely on land and many of them dwell in the trees. They are proficient at climbing these trees. This species is a known insectivore, but can be

frugivorous A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance an ...

. Therefore, ''O. nigripes'' is considered an omnivore. They scavenge for nutrient sources in things such as fruits, insects, and seeds.

Karyotype

There are 31 pairs of

chromosomes A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

found in the ''Oligoryzomys nigripes'' species. The diploid formula for this species is 2n=62. There are 60 autosomal chromosomes and 2

sex chromosomes A sex chromosome (also referred to as an allosome, heterotypical chromosome, gonosome, heterochromosome, or idiochromosome) is a chromosome that differs from an ordinary autosome in form, size, and behavior. The human sex chromosomes, a typical ...

found in this species.

References

* {{Taxonbar, from=Q1766677 Oligoryzomys Mammals described in 1818