''Nephelomys levipes'', also known as the nimble-footed oryzomysMusser and Carleton, 2005, p. 1150 or light-footed rice rat, is a species of

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 ...

in the genus '' Nephelomys'' 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 over 870 species, it is either the largest or second-largest family ...

.Weksler et al., 2006, p. 18 It is found on the eastern slope of the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

from southeastern

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

into west-central

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, Montane forest, montane, Tropical and subtropical moist broadleaf forests, moist forest characteri ...

at elevations from . It occurs in the same general area as its congener '' N. keaysi'', but at higher altitudes. In 1902,

Oldfield Thomas Michael Rogers Oldfield Thomas (21 February 1858 – 16 June 1929) was a British zoologist. Career Thomas worked at the Natural History Museum, London, Natural History Museum on mammals, describing about 2,000 new species and subspecies for ...

first described this species, under the name ''Oryzomys levipes'', on the basis of specimens from both Peru and Bolivia. He compared it to the previously described ''O. keaysi'', the current ''Nephelomys keaysi'', of which he considered it to be a "smaller form".Thomas, 1902, p. 129 In 1944,

Philip Hershkovitz Philip Hershkovitz (12 October 1909 – 15 February 1997) was an American mammalogy, mammalogist. Born in Pittsburgh, he attended the Universities of Pittsburgh and Michigan and lived in South America collecting mammals. In 1947, he was appointed ...

relegated both ''O. levipes'' and ''O. keaysi'' to the

synonymy A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of '' O. albigularis'', where it remained until it was reinstated a species in the early 1990s on the basis of genetic and other differences. When ''O. albigularis'' and related species were reclassified into a new genus, ''Nephelomys'', in 2006, it was retained as a separate species, but under the name of ''Nephelomys levipes''. It is similar to ''N. keaysi'', but smaller, and the fur on the underparts is buffy instead of whitish in the specimens Thomas examined. The

interorbital region The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups. In oryzomyine rodents, for example, the width, form, and ...

of the skull is narrow. The

incisive foramina In the human mouth, the incisive foramen (also known as: "''anterior palatine foramen''", or "''nasopalatine foramen''") is the opening of the incisive canals on the hard palate immediately behind the incisor teeth. It gives passage to blood vesse ...

, which perforate the

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...

between the

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

s and the

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

, are long and narrow. The bony palate is short, with its posterior end often located between the third molars. The

alisphenoid strut In some rodents, the alisphenoid strut is an extension of the alisphenoid bone that separates two foramina in the skull, the masticatory–buccinator foramen and the foramen ovale accessorium. The presence or absence of this strut is variable be ...

, an extension of the

alisphenoid The greater wing of the sphenoid bone, or alisphenoid, is a bony process of the sphenoid bone, positioned in the skull behind each eye. There is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, ...

bone of the skull that separates two

foramina In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, arter ...

(openings) in the skull, is present in some individuals. The

mastoid The mastoid part of the temporal bone is the posterior (back) part of the temporal bone, one of the bones of the skull. Its rough surface gives attachment to various muscles (via tendons) and it has openings for blood vessels. From its borders, t ...

bone usually contains some openings.Weksler et al., 2006, p. 19 In the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, the head and body length is 130 mm, the tail length is 160 mm, the hindfoot length (without claws) is 31 mm, the ear length is 27 mm, and the skull length is 35.7 mm.

References

Literature cited

* Hershkovitz, P. 1944. A systematic review of the Neotropical water rats of the genus ''Nectomys'' (Cricetinae). Miscellaneous Publications Museum of Zoology, University of Michigan 58: 1–88. * * Thomas, O. 1901. New mammals from Peru and Bolivia, with a list of those collected from the Inambari River, Upper Madre de Dios. Annals and Magazine of Natural History (7)7:178–190. * * Zeballos, H., Vargas, J. and Weksler, M. 2008. . In IUCN. 2008 IUCN Red List of Threatened Species. Retrieved on April 24, 2009. {{Taxonbar, from=Q1767494 Mammals of Bolivia Mammals of Peru Nephelomys Mammals described in 1902 Taxa named by Oldfield Thomas Taxonomy articles created by Polbot