Neotropical region (Costa Rica to Brazil), apparently not found in Northeastern of South America.
Color grey with yellowish on the sides; size larger in this group: head and body 175mm, tail 248mm, lower leg 40mm, hind foot 24-25mm, ear 21mm. Adult male.
The largest species of the group (head and body 229mm; tail 226mm; hind foot 29mm; ear 23mm), distinguish from M. cinereaby its dark yellowish belly, narrowest of its nasals and interorbital region and uniformly brown tail. Adult male.
Chapada - MT, Brazil.
Larger size, paler and shorter tail then M. cinereaand wider skull, more expanded nasals and multicolor tail than M. regina; dimensions of the type: head and body 180mm; tail 195mm; hind foot 27mm; ear 31mm. Adult male.
A little smaller than the other members of cinerea group (dimensions of the type: head and body 166mm; tail 250mm; hind foot 24mm). It differs from M. cinerea by the greater extent of the brown part of its tail. Adult female.
Villa Rica, Paraguay; Lagoa Santa/MG, Brazil; Sta. Catarina, Brazil (range from Southern part of Brazil to Eastern Paraguay).
Mouse gray, length of head and body 160 mm, length of tail 220mm, length of hind foot 27mm.
Type locality: Costa Rica, Cartago, "Tres Rios".
Type locality: Brazil, Mato Grosso, Chapada.
Type locality: Guyana, E. Demerara-West Coast Berbice, "Comaccka, 80 miles up Demerara river". Synonyms: cinerea, limae, paraguayana, travassosi, and others.
Type locality: Colombia, West Cundinamarca, Bogotá Region.
alstoni constantiae demerarae paraguayanus phaeus regina