Phyllotis limatus is a newly recognized species whose northern populations comprise those historically placed in P. xanthopygus limatus and the Pacific slope of the Andes populations previously included in P. x. rupestris. The geographic distribution of the northern and southern populations of P. limatus, and the northern subspecies of P. xanthopugus are presented below.
Phyllotis limatus is distinguished from P. xanthopygus by relatively narrow and deep incisors (depth > 0.9 width), a trait unique within Phyllotis, lighter color, and a slightly longer tail. Additionally, cytochrome b DNA sequence data supports removal of P. limatus from P. xanthopygus (Steppan, 1995a).