=Thomomys bottae rubidus= new subspecies
_Holotype._--Adult female, skin and skull, number 72954, Museum of Natural History, University of Kansas, trapped by Richard S. Miller and Phillip M. Youngman, original number 253 (PMY), 2-9/10 miles east of Canon City, 5344 feet, Fremont County, Colorado, March 17, 1957.
_Distribution._--Known only from Garden Park in Canon City and from the type locality (see fig. 1).
_Distinctive characters._--Dark (Reddish Brown 5YR 3/3); size large (see measurements); skull large; rostrum wide; zygomatic arches rounded and broadly spreading (see fig. 7); alveolar length of upper maxillary tooth-row small.
_Comparisons._--From topotypes of _T. b. internatus_, _T. b.
rubidus_ differs as follows: uniformly darker; skull averages larger in all measurements, except alveolar length of upper maxillary tooth-row, which is smaller; rostrum proportionately wider and tapered anteriorly; zygomatic arches more rounded; bullae more rounded in lateral view.
Specimens of _T. b. rubidus_ differ from topotypes of _T. b.
pervagus_ in darker color; rostrum wider posteriorly; posterior extensions of premaxillae shorter; bullae smaller, proportionately more inflated posteriorly; zygomatic arches more rounded; wider across squamosals; alveolar length of upper maxillary tooth-row greater.
From topotypes of _T. b. cultellus_, _T. b. rubidus_ differs as follows: paler; larger in all measurements taken; rostrum proportionately wider; zygomatic arches more rounded, less angular; angle formed by zygomatic arch and rostrum greater; bullae proportionately smaller, not so pointed anteriorly; alveolar length of upper maxillary tooth-row shorter.
_Remarks._--The range of _T. b. rubidus_ is surrounded by the range of _T. b. internatus_; nevertheless, intergradation has not been found. For a discussion of the geographic relation of _T. b. rubidus_ to _T. b.
internatus_ see page 374.
_Specimens examined._--Total 7. Fremont Co.: Garden Park, Canon City, 5344 ft., 1; _2-9/10 mi. E Canon City, 5344 ft._, 6.
SUMMARY
A study of 249 specimens of _Thomomys bottae_ from Colorado reveals six subspecies in the state. _T. b. aureus_ and _T. b. howelli_ occupy the Colorado Plateau Region in the western and southwestern parts of the state. _T. b. internatus_, _T. b. cultellus_, _T. b. pervagus_, and the newly named _T. b. rubidus_ occupy part of the Southern Rocky Mountain Region and a narrow strip of the Great Plains.
The greatest amount of geographic variation, in _Thomomys bottae_ in Colorado, occurs in the ecotone between the grassland and coniferous forest at the edge of the Great Plains, and in the ecotone between the Pinon, juniper, and sage of the Colorado Plateau and the Coniferous forest of the southern Rocky mountains.
LITERATURE CITED
BAILEY, V.
1910. Two new pocket gophers of the genus _Thomomys_. Proc. Biol.
Soc. Washington, 23:79-80, May 4.
1915. Revision of the pocket gophers of the genus Thomomys. U. S.
Dept. Agric., Bur. Biol. Surv., N. Amer. Fauna, 39:1-136, 8 pls., 10 figs, in text, November 15.
DAUBENMIRE, R. F.
1943. Vegetational zonation in the Rocky Mountains. Bot. Rev., 9:325-393, June.
DURRANT, S. D.
1952. Mammals of Utah. Univ. Kansas Publ., Mus. Nat. Hist., 6:1-549, 91 figs. August 10.
FENNEMAN, N. M.
1931. Physiography of western United States. McGraw Hill Book Co., New York, xiii + 534 pp., 173 figs., 1 map in cover pocket.
GOLDMAN, E. A.
1936. _New pocket gophers of the genus_ Thomomys. Jour. Washington Acad. Sci., 26(3):111-120, March 15.
GRINNELL, J.
1931. A new pocket gopher from southeastern California. Univ.
California Publ. Zool., 38(1):1-10, 2 pls., October 17.
KELSON, K. R.
1951. Two new subspecies of Thomomys bottae from New Mexico and Colorado. Univ. Kansas Publ., Mus. Nat. Hist, 5(6):59-71, 1 fig. in text, October 1.
MUNSELL, A. H.
1954. Munsell soil color charts. Munsell Color Co., Inc., Baltimore.
_Transmitted November 14, 1957._
27-1765