Comparisons.—Compared to topotypes of Thomomys bottae absonus, alexandrae differs as follows: Size smaller in every measurement taken. Color: Upper parts Cinnamon Buff as contrasted with Light Ochraceous Buff. Skull: Smaller in every measurement taken except interorbital breadth and alveolar length of upper molar series which are larger; molariform teeth larger.
Among named races of Thomomys bottae occurring in Utah, alexandrae most resembles T. b. aureus to the northeast. It can be distinguished from topotypes of the latter by: Size smaller in every measurement taken. Color: Darker throughout. Skull: Smaller, slenderer and more nearly flat; palate nearly flat as opposed to arched; zygomatic arches weaker and not so widely spreading; interparietal narrower; tympanic bullae smaller; dentition weaker.
Remarks.—Goldman (1933:464) accorded alexandrae full specific status, because he found no intergradation with other races, from which he thought alexandrae had been isolated perhaps for thousands of years by the barriers of the surrounding terrain. Benson (1935:450) noted resemblances between alexandrae and specimens of latirostris from Keams Canyon, Zuni Well, and Winslow in Navajo County, Arizona (= aureus), and also between alexandrae and absonus from Houserock Valley, Arizona. He thought that alexandrae is no more differentiated or isolated than each of several other kinds of desert pocket gophers, and, therefore, accorded alexandrae only subspecific status, as I, also, am inclined to do.
Specimens examined.—One (M. V. Z.) from Soldier Spring, Navajo Mountain, 8,600 ft., San Juan County. Fourteen topotypes from Arizona also were examined.
Measurements of Adult Males of Thomomys
(In millimeters)
| Total length | Length of tail | Length of hind foot | Basilar length | Length of nasals | Zygomatic breadth | Mastoid breadth | Interorbital breadth | Alveolar length of upper molar series | Extension of premax post. to nasals | Length of rostrum | Breadth of rostrum | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| T. b. aureiventris, 4; topotypes (Hall, 1930:446) | ||||||||||||
| Av. | 243 | 67 | 32 | 36.4 | 14.7 | 26.5 | 21.5 | 6.6 | 7.9 | 2.4 | .... | ... |
| Min. | 232 | 59 | 31 | 35.3 | 14.0 | 25.5 | 20.9 | 6.1 | 7.8 | 1.8 | .... | ... |
| Max. | 253 | 72 | 33 | 37.1 | 15.3 | 27.3 | 22.3 | 6.9 | 8.0 | 3.4 | .... | ... |
| T. b. centralis, 9; topotypes (Hall, 1930:446) | ||||||||||||
| Av. | 237 | 75 | 30 | 36.3 | 14.6 | 25.2 | 20.7 | 6.6 | 8.0 | 3.2 | .... | ... |
| Min. | 215 | 61 | 29 | 34.5 | 13.9 | 24.6 | 19.7 | 5.8 | 7.5 | 2.2 | .... | ... |
| Max. | 250 | 83 | 32 | 38.0 | 15.9 | 26.1 | 21.9 | 7.2 | 8.7 | 4.5 | .... | ... |
| T. b. albicaudatus, 7; topotypes (Hall, 1930:446) | ||||||||||||
| Av. | 228 | 65 | 31 | 35.4 | 14.0 | 26.1 | 20.5 | 6.6 | 8.1 | 3.2 | .... | ... |
| Min. | 223 | 59 | 29 | 34.9 | 13.4 | 24.9 | 19.8 | 6.4 | 7.8 | 3.0 | .... | ... |
| Max. | 235 | 72 | 32 | 36.1 | 15.1 | 27.8 | 21.1 | 6.9 | 8.4 | 3.8 | .... | ... |
| T. b. robustus, 9; topotypes | ||||||||||||
| Av. | 222 | 65 | 29 | 34.1 | 13.6 | 26.0 | 20.8 | 6.4 | 7.8 | 2.7 | 15.7 | 8.4 |
| Min. | 214 | 59 | 28 | 32.6 | 13.0 | 25.2 | 20.0 | 6.1 | 7.3 | 2.0 | 14.7 | 8.1 |
| Max. | 236 | 70 | 31 | 35.7 | 14.4 | 26.7 | 21.5 | 6.7 | 8.2 | 3.0 | 17.0 | 8.8 |
| T. b. stansburyi, 5; topotypes | ||||||||||||
| Av. | 206 | 60 | 28 | 32.3 | 12.4 | 22.4 | 19.1 | 6.3 | 7.6 | 2.8 | 14.7 | 7.5 |
| Min. | 198 | 58 | 26 | 30.6 | 12.0 | 21.5 | 18.2 | 6.2 | 7.0 | 2.5 | 14.1 | 7.1 |
| Max. | 215 | 68 | 31 | 33.4 | 13.0 | 23.1 | 20.1 | 6.5 | 8.0 | 3.0 | 15.4 | 7.8 |
| T. b. nesophilus, 4; topotypes | ||||||||||||
| Av. | 230 | 69 | 32 | 35.3 | 14.4 | 25.5 | 20.4 | 6.8 | 8.4 | 2.5 | 17.1 | 8.2 |
| Min. | 220 | 60 | 30 | 33.6 | 14.1 | 24.9 | 19.8 | 6.5 | 8.2 | 2.1 | 16.4 | 7.6 |
| Max. | 242 | 75 | 33 | 36.5 | 14.8 | 26.2 | 21.1 | 7.1 | 8.7 | 2.9 | 18.4 | 8.6 |
| T. b. minimus, 2; topotypes | ||||||||||||
| Av. | 184 | 60 | 25 | 30.7 | 11.3 | 21.3 | 18.7 | 6.4 | 7.4 | 2.5 | 13.9 | 7.5 |
| Min. | 179 | 55 | 24 | 28.7 | 10.2 | 20.2 | 17.8 | 6.3 | 7.3 | 2.5 | 12.9 | 7.0 |
| Max. | 189 | 64 | 26 | 32.8 | 12.5 | 22.4 | 19.6 | 6.4 | 7.6 | 2.5 | 15.0 | 7.9 |
| T. b. lenis, 2; topotypes | ||||||||||||
| Av. | 251 | 80 | 32 | 39.7 | 16.0 | 28.6 | 22.6 | 6.8 | 8.3 | 3.4 | 18.4 | 8.8 |
| Min. | 248 | 74 | 31 | 39.4 | 15.8 | 28.4 | 22.4 | 6.6 | 8.2 | 3.0 | 17.9 | 8.6 |
| Max. | 255 | 86 | 32 | 29.9 | 16.2 | 28.7 | 22.7 | 6.9 | 8.5 | 3.7 | 18.8 | 8.9 |
| T. b. contractus, 8; topotypes | ||||||||||||
| Av. | 229 | 74 | 31 | 33.3 | 12.5 | 23.7 | 19.1 | 6.6 | 7.6 | 3.0 | 15.4 | 7.3 |
| Min. | 209 | 63 | 28 | 30.0 | 10.9 | 21.4 | 17.7 | 6.3 | 7.2 | 2.4 | 13.5 | 6.5 |
| Max. | 255 | 85 | 33 | 37.4 | 14.5 | 26.4 | 20.9 | 6.9 | 8.0 | 3.5 | 18.2 | 8.0 |
Measurements of Adult Males of Thomomys—Continued