''Amphinectomys savamis'', also known as the Ucayali water ratMusser and Carleton, 2005 or amphibious rat,Duff and Lawson, 2004 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 ...

from the

Peruvian Amazon Peruvian Amazonia ( es, Amazonía del Perú) is the area of the Amazon rainforest included within the country of Peru, from east of the Andes to the borders with Ecuador, Colombia, Brazil and Bolivia. This region comprises 60% of the country ...

. It is placed as the only member of genus ''Amphinectomys'' in the 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 ...

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 ...

. It is similar to ''

Nectomys ''Nectomys'' is a genus of rodent in the tribe Oryzomyini of family Cricetidae. Musser and Carleton, 2005. It is closely related to '' Amphinectomys'' and was formerly considered congeneric with ''Sigmodontomys''. It consists of five species, whic ...

'', but its discoverers considered it to be different enough (with more expansive interdigital webbing and a significantly broader interorbital region) to require its own genus. When it was described as a new genus in 1994, knowledge of the variation within ''Nectomys'' was much more limited than it is now, and it has been suggested that the status of the taxon be re-examined considering this new information. The species's karyotype, 2n = 52, falls within the known range of ''Nectomys'' (2n = 38 - 59).

References

Literature cited

*Duff, A. and Lawson, A. 2004. Mammals of the World: A checklist. New Haven, Connecticut: Yale University Press, 312 pp. *Malygin, V.M., Aniskin, V.M., Isaev, S.I. and Milishnikov, A.N. 1994. ''Amphinectomys savamis'' Malygin Gen. et sp. n., a new species and a new genus of water rat (Cricetidae, Rodentia) from Peruvian Amazonia. Zoologicheskii Zhurnal 73:195-208. *Pacheco, V., Zeballos, H. and Vivar, E. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2.
www.iucnredlist.org
. Downloaded on December 8, 2009. Mammals of Peru Oryzomyini Mammals described in 1994 Aquatic mammals {{Sigmodontinae-stub