Oligoryzomys fulvescens, also known as the fulvous colilargo, fulvous pygmy rice rat, or northern pygmy rice rat, is a species of rodent in the genus Oligoryzomys of family Cricetidae. It is found from southern Mexico through Central America into South America, where it occurs south into Peru and Brazil, and includes numerous synonyms, including the type species of the genus, Oryzomys navus Bangs, 1899. The taxonomy of this species is unresolved, and it may be found to contain more than one species. Its karyotype has 2n = 54-60 and FNa = 68-74.
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