From topotypes of _Thomomys bottae albicaudatus_, _wahwahensis_ differs as follows: Hind foot shorter. Color: Lighter throughout, Pinkish Buff as opposed to (13''''_n_) Black. Skull: Smaller and more nearly flat; rostrum shorter, wider and more nearly flat; nasals straight as opposed to convex; zygomatic breadth less but mastoid breadth greater; tympanic bullae smaller, and less inflated ventrally; extension of premaxillae posterior to nasals less; molariform teeth smaller. From topotypes of _Thomomys bottae aureiventris_, _wahwahensis_ differs in the following features: Size smaller; hind foot shorter. Color: Lighter throughout, no "gold" on underparts. Skull: Smaller in nearly every measurement taken; rostrum shorter and relatively wider; zygomatic arches more angular and relatively more widely spreading; nasals shorter and more nearly flat; thickening at union of jugal and zygomatic process of maxilla less; interpterygoid space V-shaped as opposed to lyre-shaped; tympanic bullae much smaller, and less inflated ventrally; molariform teeth much smaller. Topotypes of _wahwahensis_ can be easily distinguished from those of _Thomomys bottae tivius_ by their markedly larger size in every measurement taken, lighter color, and larger, more robust and more nearly flat skull. For comparisons of _wahwahensis_ with _Thomomys bottae sevieri_, _robustus_, _bonnevillei_ and _convexus_ see comparisons under those forms. Among the named races of _Thomomys bottae_, _wahwahensis_ definitely has its affinities with _planirostris_ from Zion National Park. Both possess flat skulls with wide, short rostra. It differs from the latter in: Size smaller in every measurement taken. Color: Lighter throughout. Skulls: Nasals and rostrum shorter and more nearly flat; tympanic bullae markedly smaller; alveolar length of upper molar series shorter; molariform teeth markedly smaller and weaker.