Pearson's chaco mouse (Andalgalomys pearsoni) is a species of rodent in the family Cricetidae.[2] This mouse is found in the Gran Chaco ecoregion of southeastern Bolivia and western Paraguay at elevations up to 400 m.[1] The species is named after American zoologist Oliver Payne Pearson.[3][4] Its karyotype has 2n = 76 and 78 in the two subspecies.[2] The latter is the highest diploid number of any species in the tribe Phyllotini.[5]