Order Rodentia - Family Cricetidae Author Wilson, Don E. Author Reeder, DeeAnn text 2005 The Johns Hopkins University Press Baltimore Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 2 955 1189 book chapter 0-8018-8221-4 10.5281/zenodo.7316535 Oligoryzomys microtis J. A. Allen 1916 Oligoryzomys microtis J. A. Allen 1916 , Bull. Am. Mus . Nat. Hist., 35: 525 . Type Locality: Brazil , Amazonas State , north bank of lower Rio Solimões, 70 km WSW Manaus, Manacaparú (as restricted by Voss et al., 2001:118-119). Vernacular Names: Small-eared Colilargo . Synonyms: Oligoryzomys chaparensis (Osgood 1916) ; Oligoryzomys mattogrossae (J. A. Allen 1916 ) . Distribution: Amazon Basin of Brazil and contiguous lowlands of Perú , Bolivia , and Paraguay . Conservation: IUCN – Lower Risk (lc). Discussion: Karyotype reported by Gardner and Patton (1976) as Oryzomys longicaudatus variant (2) for Peruvian sample; slightly different diploid and fundamental numbers documented for specimens from Amapá , Brazil ( Andrades-Miranda et al., 2001 a ). Gene sequence analyses indicate that O. microtis and O. fornesi represent separate species groups ( Myers et al., 1995 ), not populations of a single species ( Carleton and Musser, 1989 ; Olds and Anderson, 1987 ). With removal of fornesi from synonymy and fixation of the type locality, specific definition and distributional limits require amendment; also see Voss et al. (2001) for comparisons with O. fulvescens and comments on taxonomy.