''Nephelomys auriventer'', also known as the golden-bellied oryzomysMusser and Carleton, 2005, p. 1146 or Ecuadorian rice rat, is a species of

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 na ...

in the genus ''

Nephelomys ''Nephelomys'' is a genus of South American oryzomyine rodents found in the Andes from Bolivia to Venezuela, with a westward extension into the mountains of Costa Rica. Its generic name is derived from the Ancient Greek word ''nephelê'' "mist", ...

'' 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 has m ...

.Weksler et al., 2006, p. 18

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

originally described it, in 1899, as a species of ''

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 ...

'', ''Oryzomys auriventer'', and considered it most similar to ''Oryzomys aureus'' (currently '' Thomasomys aureus'').Thomas, 1899, p. 380 In 1926, a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

was described from an Ecuadorian locality, ''Oryzomys auriventer nimbosus'', and it was suggested that ''O. auriventer'' was closely related to '' O. albigularis''. This proposal was formalized in 1961 by including ''O. auriventer'' within the species ''O. albigularis'', but by 1976 ''O. auriventer'' was recognized again as a separate species. In 2006, ''Oryzomys albigularis'' and related species, including ''O. auriventer'', were transferred to the new genus ''Nephelomys''. Simultaneously, the former subspecies ''nimbosus'' was recognized as a separate species, '' Nephelomys nimbosus''. ''N. auriventer'' is a fairly large species, though it is somewhat smaller than the

black rat The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is n ...

(''Rattus rattus''). It has fine, not woolly fur which is about in length at the back. The upperparts are blackish, becoming lighter towards the sides.Thomas, 1899, p. 379 The coloration of the upperparts is sharply divided from that of the underparts, which is ochraceous. The large ears are brown. The tail is long and almost lacks hairs; it is dark brown above and slightly lighter below. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, an old male, has head and body length , tail length , hindfoot length (without claws) and ear length . The form of 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, an ...

of the skull is distinctive, featuring distinctly beaded margins that converge towards the front. Unusually for a ''Nephelomys'', the

jugal The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy ...

bone of the skull is large. 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; there is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backward. Structure The greater wi ...

bone of the skull which separates two openings in the skull, is sometimes present. The subsquamosal fenestra, an opening in the posterior part of the skull, is relatively small. 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, ...

bone is completely ossified, lacking the openings that are present in most species of the genus.Weksler et al., 2006, p. 19 It is found in eastern

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...

and northern

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

on the eastern slope of the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

at elevations from 1000 to 2900 m. It is uncommon in Ecuador, and so far it has been found in only one locality in Peru, far to the south of its Ecuadorian range. It occurs in

páramo Páramo () can refer to a variety of alpine tundra ecosystems located in the Andes Mountain Range, South America. Some ecologists describe the páramo broadly as "all high, tropical, montane vegetation above the continuous timberline". A narrower ...

and a variety of forest habitats.

References

Literature cited

*Anthony, H.E. 1926. Preliminary report on Ecuadorean mammals. No. 7. ''American Museum Novitates'' 240:1–6. *Musser, G.G. and Carleton, M.D. 2005. Superfamily Muroidea. Pp. 894–1531 in Wilson, D.E. and Reeder, D.M. (eds.). Mammal Species of the World: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University Press, 2 vols., 2142 pp. *Thomas, O. 1899. Descriptions of new rodents from the Orinoco and Ecuador. Annals and Magazine of Natural History (7)4:378–382. * *Weksler, M., Tirira, D. and Boada, C. 2008. . In IUCN. 2008

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

. Retrieved on November 2, 2009. {{Taxonbar, from=Q1770776 Mammals of Ecuador Mammals of Peru Nephelomys Mammals described in 1899 Páramo fauna Taxa named by Oldfield Thomas Taxonomy articles created by Polbot