Part 5

Specimens examined.--Total 93. Chaffee Co.: 2 mi. NNW Salida, 7100 ft., 3; Salida, 28 (20 ERW, 8 USNM). Fremont Co.: 12 mi. N Canyon City, 5; 1 mi. W Coaldale, 8; Cotopaxi, 1 (CSU); 5 mi. S Cotopaxi, 12. El Paso Co.: 1-1/4 mi. S Colorado Springs, 2; 9 mi. SSW Colorado Springs, 2; 17 mi. S Colorado Springs, 1. Custer Co.: 2-1/2 mi. S Wetmore, 3; Santa Fe Drive and 20th Lane, Blende, 1; St. Charles Mesa, 5600 ft., 2 (CSU); Fork of Huerfano and Cucharas rivers, 2 (CMNH). Huerfano Co.: 11 mi. WNW Gardner, 7000 ft., 3; Gardner, 7000 ft., 2 (USNM); 1-1/2 mi. S Redwing, 3; Bear Creek, near Walsenburg, 2 (CSU); 1 mi. E La Veta, 8; 5 mi. SE La Veta, 2.

=Thomomys bottae cultellus= Kelson

Thomomys bottae cultellus Kelson, Univ. Kansas Publ., Mus. Nat. Hist., 5:64, October 1, 1951.

Thomomys fulvus, Cary, Proc. Biol. Soc. Washington, 20:26, March 27, 1907; Warren, Colorado College Publ., 33:76, January, 1908; Warren, Mammals of Colorado, p. 80, 1910.

Thomomys fulvus fulvus, Bailey, N. Amer. Fauna, 39:80, November 15, 1915.

Holotype.--Adult male, skin and skull, number 70919, United States National Museum, Halls Peak, Mora County, New Mexico; January 13, 1895, obtained by C. Barber.

Distribution.--Raton Section of the Great Plains in northern New Mexico and extreme southern Colorado (see fig. 1).

Distinctive characters.--Dark (topotypes); size medium (see measurements); posterior tongues of premaxillae short; posterior margins of nasals forming a V (see fig. 5).

Comparisons.--From T. b. pervagus, topotypes of T. b. cultellus differ as follows: darker, not so reddish; smaller; skull smaller; zygomatic arches relatively longer; bullae proportionately smaller and less inflated; basioccipital proportionately wider; posterior tongues of premaxillae shorter.

Topotypes of T. b. cultellus most closely resemble those of T. b. internatus but differ as follows: darker; zygomatic arches more widely spreading, not so nearly parallel; nasals not so wide; bullae slightly more inflated.

For a comparison with T. b. rubidus see the account of that subspecies.

Remarks.--Kelson (1951:64) named T. b. cultellus on the basis of six dark specimens (Dark Reddish Brown 5YR 3/4 and 2/2). Nowhere else within the range of this subspecies, as defined by Kelson, do any specimens resemble the topotypes in color.

After comparing topotypes of T. b. cultellus with topotypes of T. b. internatus of approximately equal age, I disagree with Kelson (loc. cit.) on some of the characters which he used to separate cultellus from internatus. My findings indicate that T. b. cultellus is not smaller, that its skull is not smaller and not less angular, and that the tympanic bullae are not less pointed ventrally. Further collecting is needed better to limit and diagnose this subspecies.

Specimens examined.--Total 13. Colorado: Las Animas Co.: Fishers Peak, about 8000 ft., 1 (USNM). New Mexico: Union Co.: Near Folsom, 4 (CMNH); Colfax Co.: Philmont Ranch, Cimarroncito, 8100 ft., 2. Mora Co.: Halls Peak, 6 (USNM).

Fig. 2. Thomomys b. aureus, 3 mi. W Durango, La Plata Co., Colorado. No. 72967, Female.

Fig. 3. Thomomys b. howelli, holotype, Grand Junction, 4600 ft., Mesa Co., Colorado. No. 75684 USNM, Female.

Fig. 4. Thomomys b. pervagus, Espanola, 5000 ft., Rio Arriba Co., New Mexico. No. 133614 USNM, Female.

Fig. 5. Thomomys b. cultellus, Fishers Peak, 8000 ft., Las Animas Co., Colorado. No. 129285 USNM, Female.

Fig. 6. Thomomys b. internatus, Salida, 7050 ft., Chaffee Co., Colorado. No. 2757 ERW, Female.

Fig. 7. Thomomys b. rubidus, holotype, 2-9/10 mi. E Canyon City, Fremont Co., Colorado. No. 72954, Female.]

=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 Canyon City, 5344 feet, Fremont County, Colorado, March 17, 1957.

Distribution.--Known only from Garden Park in Canyon 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.