Genus Thomomys Wied (continued 2)

Specimens examined.—Total, 49, distributed as follows: Millard County: 1 mi. SE Gandy, 5,000 ft., 15 (M. V. Z.); White Valley (Tule Spring), 60 mi. W Delta, 4, (3 in R. W. Fautin Vertebrate Collection); Robison Ranch, 5,300 ft., (on Hendry Creek) Simonsons Ranch, 4,596 ft., 2 (M. V. Z.); 1 mi. E Garrison, 5,000 ft., 21; 5 mi. S Garrison, 5,400 ft., 5 (M. V. Z.). Iron County: Cedar City, 2 (M. V. Z.).

Thomomys bottae sevieri new subspecies

Type.—Female, adult, skin and skull, No. 2530, Museum of Zoölogy, University of Utah; Swasey Spring, House Mountains, 6,500 ft., Millard County, Utah; May 16, 1938; collected by S. D. Durrant; original number 1380.

Range.—Known only from the type locality.

Diagnosis.—Size medium (see measurements); claws on front feet short and weak; ears short; tail relatively long. Color: Upper parts Pinkish Buff, grading over sides to Pale Pinkish Buff on underparts; nose, top of head, chin and cheeks grayish black; postauricular patches small and grayish black; front and hind feet and distal two-thirds of tail white. Skull: Small, weak and smooth; rostrum narrow; nasals narrow, not markedly flared distally; zygomatic arches weak, not angular, and of "graceful" contour; lacrimal processes small; characteristic dorsal depression present in region of sagitto-coronal suture; mastoid and zygomatic breadths narrow; occiput narrow and high; braincase well inflated; paroccipital processes small and smooth; interpterygoid space narrowly V-shaped; tympanic bullae small, but well inflated ventrally; alveolar length of upper molar series short; molars small; upper incisors short, but narrow.

Comparisons.—From topotypes of Thomomys bottae aureiventris, sevieri differs as follows: Size smaller. Color: Lighter throughout, no "gold" on underparts. Skull: Much smaller in every measurement taken, less massive and not angular; zygomatic arches weaker and widest posteriorly rather than anteriorly; union of jugal and zygomatic process of maxilla not greatly thickened; interpterygoid space narrowly V-shaped rather than lyre-shaped; pterygoid hamulae shorter and weaker; tympanic bullae smaller, but markedly more inflated ventrally; dentition smaller and weaker.

From near topotypes of Thomomys bottae centralis, sevieri can be distinguished by the following features: Size markedly smaller. Color: Lighter throughout. Skull: Markedly smaller in every measurement taken, weaker and smoother; zygomatic arches weaker, less angular and more "graceful"; rostrum shorter, but narrower; lacrimal processes smaller; tympanic bullae smaller, but more inflated ventrally, being triangular in shape as opposed to ovate and with anteromedial margin decidedly pointed; pterygoid hamulae smaller and weaker; dentition smaller and weaker.

T. b. sevieri can readily be distinguished from Thomomys bottae albicaudatus by the following features: Size smaller in every measurement taken. Color: Markedly lighter throughout. Skull: Smaller, and weaker; rostrum shorter and narrower; ascending processes of premaxillae narrower; extension of premaxillae posterior to nasals shorter; posterior tongues of premaxillae narrower; dentition much lighter.

Comparisons of sevieri with topotypes of Thomomys bottae wahwahensis show them to be of approximately the same size, but to differ as follows: Hind foot longer; ear shorter. Color: Slightly darker. Skull: Smaller, weaker, less ridged; zygomatic breadth less; zygomatic arches markedly less angular; mastoid breadth less; rostrum much longer and narrower, not as blunt nor flattened; tympanic bullae much larger and more inflated ventrally; braincase vaulted as opposed to flattened.

From topotypes of Thomomys bottae bonnevillei, sevieri differs in: Size smaller throughout. Skull: Smaller in every measurement taken, weaker, smoother and less angular; dentition smaller and weaker.

Topotypes of sevieri are easily distinguished from those of Thomomys bottae robustus by smaller size, and smaller, markedly weaker skull which is less angular and ridged.

Among named races of Thomomys bottae, sevieri is closest geographically to convexus, but differs from it as follows: Size larger; hind foot longer. Skull: Smaller in every measurement taken; nasals shorter and not so flaring distally; rostrum weaker, narrower and not so depressed; zygomatic arches markedly weaker and less angular; lacrimal processes smaller; supraoccipital narrower and higher; paroccipital processes weaker; tympanic bullae smaller; dentition markedly weaker.

Topotypical specimens of sevieri can be readily distinguished from those of Thomomys bottae tivius by Pinkish Buff instead of Mummy Brown on upper parts. Tympanic bullae larger and markedly more inflated; nasals longer; zygomatic and mastoidal breadths greater; rostrum longer and more depressed; upper incisors longer and wider; molariform teeth smaller. The skulls of sevieri resemble those of tivius more closely than those of any other subspecies.

Remarks.—The House Mountains in western Millard County are surrounded by desertlike terrain that is seemingly unsuited to pocket gophers. In these mountains, gophers were sought in vain at several localities, including Antelope Springs which superficially appeared suitable for the animals. Pocket gophers were found only at the type locality, Swasey Spring, which is well above the highest level of the Pleistocene Lake Bonneville. T. b. sevieri, like T. b. minimus on Stansbury Island, Great Salt Lake, appears to remain only on land that was an island when Lake Bonneville was at its highest level.

Specimens examined.—Total, 10, from the type locality.

Thomomys bottae convexus Durrant

Thomomys bottae convexus Durrant, Proc. Biol. Soc. Washington, 52:159, October 11, 1939.

Type.—Male, adult, skin and skull, No. 2482, Museum of Zoölogy, University of Utah; E side Clear Lake, 4,600 ft., Millard County, Utah; May 20, 1938; collected by S. D. Durrant; original number 1401.

Range.—Westcentral Utah in Delta Valley.

Diagnosis.—Size medium (see measurements). Color: Upper parts and sides Pinkish Buff, purest on sides; underparts Pale Pinkish Cinnamon; inguinal and pectoral regions Pale Pinkish Buff; nearly all specimens have white on perineal region; nose grayish black; front feet, hind feet and distal third to half of tail white; postauricular patches black. Skull: Braincase moderately convex on dorsal surface; rostrum strongly depressed, giving the entire dorsal surface of the skull a "rocker-shape"; zygomatic arches heavy, short and widely spreading, widest posteriorly; upper incisors recurved, short and wide; molariform teeth large; alveolar length of upper molar series long; palatal pits deep; tympanic bullae moderately inflated ventrally; mastoidal breadth actually as well as relatively wide.

Comparisons.—Compared with topotypes of Thomomys bottae wahwahensis, convexus is of approximately the same color, but differs as follows: Size smaller; tail, hind foot, and ear shorter. Skull: Rostrum longer, narrower and more depressed; skull convex rather than flat; nasals longer, and convex rather than flat; tympanic bullae larger; zygomatic arches shorter and more massive; molariform teeth larger.

From topotypes of Thomomys bottae centralis, convexus differs in: Size smaller; tail and hind foot shorter. Color: Uniformly lighter, more white in perineal region. Skull: Smaller, more convex; rostrum shorter, wider and more depressed; zygomatic arches shorter and heavier; mastoidal breadth actually, as well as relatively wider; tympanic bullae more inflated ventrally; upper incisors shorter and wider.

Comparatively, topotypes of convexus can be distinguished from those of Thomomys bottae aureiventris by: Size smaller; tail and hind foot shorter. Color: Darker on upper parts; no "gold" on underparts. Skull: Smaller and more nearly flat; rostrum shorter and more depressed; zygomatic arches shorter, heavier and widest posteriorly rather than anteriorly; interpterygoid space V-shaped as opposed to lyre-shaped; upper incisors shorter, narrower and more recurved.

Topotypical specimens of convexus differ from those of Thomomys bottae nesophilus as follows: Size smaller; tail and hind foot shorter. Color: Uniformly lighter throughout, Cinnamon Buff as opposed to Pinkish Buff. Skull: Smaller; rostrum heavier, shorter and more depressed; zygomatic arches shorter, heavier and not so widely spreading; no widening of supraoccipital as in nesophilus; upper incisors shorter and more recurved.

When compared with topotypes of Thomomys bottae albicaudatus, convexus shows the following differences: Size smaller; tail and hind foot shorter. Color: Markedly lighter throughout. Skull: Smaller, more convex and compact; rostrum shorter, heavier, more depressed and compact; zygomatic arches shorter and more robust; upper incisors shorter and more recurved.

Thomomys bottae tivius is the race closest geographically to convexus. From it, convexus can be readily distinguished by: Size larger; tail shorter; hind foot longer. Color: Markedly lighter throughout. Skull: Much heavier and more compact, weights of skulls of males and females of the two subspecies being 2.4 grs., 1.6; 1.6, 1.2, respectively; rostrum heavier, wider and more depressed; zygomatic arches shorter, and more massive; upper incisors shorter, wider and more recurved; molariform teeth larger.

For comparisons with Thomomys bottae lenis, contractus, sevieri, bonnevillei, and robustus see accounts of those forms.

Remarks.—T. b. convexus is limited to the area around Clear Lake in Millard County. This lake is surrounded by areas of loose, shifting sand and flat areas of barren alkali. The lake is fed by springs which flow from lava outcroppings on its eastern side. As far as discernible, the only area populated by pocket gophers (1938) was that adjacent to the lake where vegetation had trapped the sand. The factor which limits the extension of range of this subspecies probably is plant food. Also, the soil is mechanically poor for burrowing, since it caves in easily and burrows were found only in the sand where salt grass (Distichlis stricta) had trapped and stabilized it. Burrows were found from the edge of the water back as far as this grass persisted.

Specimens examined.—Total, 17, from the type locality.

Thomomys bottae tivius Durrant

Thomomys bottae tivius Durrant, Bull. Univ. Utah, 28 (No. 4):5, August 18, 1937.

Type.—Female, adult, skin and skull, No. 1827, Museum of Zoölogy, University of Utah; Oak Creek Canyon, 6 mi. E Oak City, 6,000 ft., Millard County, Utah; September 14, 1936; collected by S. D. Durrant; original number 1100.

Range.—Limited to the Cañon Mountains, Millard County.

Diagnosis.—Size small (see measurements). Color: Upper parts Mummy Brown, grading through Cinnamon on the sides to Pale Cinnamon on the underparts; cheeks Cinnamon; postauricular patches black; distal third to half of tail white. Skull: Small, weak; zygomatic arches weak, not widely spreading, widest posteriorly; tympanic bullae large; interpterygoid space V-shaped; nasals short, usually simple distally, but with some denticulations in some specimens; palatal pits deep; palate narrow; paroccipital processes small; incisors, both upper and lower, narrow; molariform teeth small.

Comparisons.—Topotypes of tivius differ from those of Thomomys bottae albicaudatus as follows: Size markedly smaller in every measurement taken. Color: Lighter, Mummy Brown as opposed to near (13''''n) Black. Skull: Smaller, slenderer and weaker; zygomatic arches weak and not widely spreading as opposed to massive and wide spreading; nasals and rostrum narrower and shorter; extension of premaxillae posterior to nasals shorter; tympanic bullae smaller; molariform teeth smaller.

For comparisons with Thomomys bottae stansburyi and T. b. contractus see accounts of those forms.

The four subspecies tivius, albicaudatus, stansburyi, and contractus are the darkest in color of all the Thomomys bottae occurring within the state.

Remarks.—This small, dark subspecies is limited to the Cañon Mountains in eastern Millard County. Apparently it is a mountain derivative of Thomomys bottae contractus which occurs in the valleys to the east and west of these mountains. Intergradation is noted with animals from the valleys on either side. For further comments on distributional problems of this type see remarks under Thomomys bottae stansburyi.

Specimens examined.—Total, 12, from the type locality.

Thomomys bottae contractus new subspecies

Thomomys perpallidus albicaudatus Hall, Univ. California Publ. Zoöl., 37:3, April 10, 1931.

Thomomys bottae albicaudatus Durrant. Bull. Univ. Utah, 28 (No. 4):4, August 18, 1937.

Type.—Male, adult, skin and skull, No. 1851, Museum of Zoölogy, University of Utah; Scipio, 5,315 ft., Millard County, Utah; September 17, 1936; collected by S. D. Durrant; original number 1125.

Range.—Extreme eastern Millard and Beaver counties, Utah.

Diagnosis.—Size medium (see measurements). Color: Upper parts Cinnamon Buff, mixed with black giving a color of Dresden Brown; sides between Cinnamon Buff and Pinkish Buff; underparts Pinkish Buff, purest on inguinal and pectoral regions; postauricular patches medium in size and black; ears covered with black hairs; nose, chin, cheeks and top of head dusky; front feet, hind feet and distal third to half of tail white; proximal part of tail covered all around with buff-colored hairs. Skull: Long, slender, moderately ridged and convex transversally at proximal ends of nasals; nasals long; rostrum long and narrow; posterior ends of nasals truncate or shallowly emarginate; ascending processes of premaxillae slender; extension of premaxillae posterior to nasals long; zygomatic arches neither robust nor widely spreading; interparietal subquadrangular; supraoccipital extending horizontally well behind lambdoidal suture instead of dropping off abruptly to the foramen magnum; interpterygoid space moderately V-shaped in some specimens, but somewhat lyre-shaped in others; tympanic bullae large and truncate anteriorly; upper incisors long and narrow; molariform teeth small and light.

Comparisons.—Compared with topotypes of Thomomys bottae albicaudatus, contractus differs as follows: Tail longer. Color: Lighter throughout. Skull: Slenderer, less ridged and angular; rostrum narrower; zygomatic and mastoidal breadths less; ascending processes of premaxillae narrower; posterior tongues of premaxillae narrower; posterior ends of nasals less truncate; zygomatic arches weaker, less angular, and less widely spreading posteriorly; interparietal larger; paroccipital processes weaker; interpterygoid space not as widely V-shaped; upper incisors longer and narrower; molariform teeth smaller.

Topotypes of contractus can be distinguished from those of Thomomys bottae convexus by the following: Size larger, tail longer; hind foot larger. Color: Darker throughout. Skull: Longer, narrower, and not as massive; top of skull moderately, as opposed to strongly, convex; nasals arched rather than straight; zygomatic arches neither as widely spreading, angular nor massive; space enclosed within zygomatic arches longer; interparietal larger; interpterygoid space more narrowly V-shaped; upper incisors longer and narrower; molariform teeth much lighter.

Comparisons of topotypes of contractus with near topotypes of Thomomys bottae centralis show them to be approximately the same size, but to differ as follows: Color: Darker throughout. Skull: Shorter and slenderer; rostrum narrower; region between posterior tongues of premaxillae narrower and more convex transversally; nasals more truncate; zygomatic breadth less, but arches relatively more widely spreading posteriorly; interparietal larger; interpterygoid space generally narrower; upper incisors longer and narrower; molariform teeth smaller.

Topotypes of contractus differ from those of Thomomys bottae aureiventris as follows: Size smaller; tail longer; hind foot shorter. Color: Darker throughout. Skull: Shorter but slenderer; rostrum narrower; nasals shorter but slenderer, and more truncate posteriorly; extension of premaxillae posterior to nasals longer; zygomatic arches weaker and less angular; zygomatic processes of maxillae weaker and with no marked thickenings at union of maxilla and jugals; interparietal larger; interpterygoid space more generally V-shaped; upper incisors longer and narrower; molariform teeth smaller.

Compared with topotypes of Thomomys bottae planirostris, contractus differs in: Size smaller throughout. Color: Darker, more black and less Cinnamon in pelage. Skull: Smaller in every measurement taken; rostrum narrower; nasals arched instead of flat; zygomatic arches neither angular, massive nor widely spreading; upper incisors narrower; molariform teeth markedly smaller and weaker.

Topotypes of contractus differ from those of Thomomys bottae levidensis in larger size, darker color and longer, slenderer skulls.

Among named races of T. bottae, contractus is closest morphologically to tivius. It differs from it as follows: Size larger throughout. Color: Lighter throughout. Skull: The same general shape and proportions, but larger in every measurement taken; rostrum longer and narrower; extension of premaxillae posterior to nasals longer; posterior tongues of premaxillae narrower.

Remarks.—Fifteen animals from Oak City are intergrades between contractus and tivius. Intergradation with lenis is also shown in some specimens by the widely spreading zygomatic arches. In the majority of characters including the diagnostic long, slender, narrow rostrum they are more like contractus to which they are here referred.

Nine animals from Beaver were considered by Hall (1931:3) and Durrant (1937:4) to be intergrades between Thomomys bottae albicaudatus and Thomomys bottae centralis. Restudy of these specimens in the light of additional material now shows them to be intergrades between T. b. centralis, T. b. planirostris and T. b. contractus. The majority of these animals are intermediate in color between centralis and contractus, but a few have the reddish cast of planirostris. The shape of the nasals is characteristic of planirostris, while the zygomatic arches are as in centralis. In the remainder of the diagnostic characters they are like contractus to which they are here referred.

Strong affinities exist between albicaudatus, tivius and contractus. All three of these races probably stemmed from a dark form which formerly inhabited the eastern mainland of the Pleistocene Lake Bonneville. At present, tivius is isolated on the Cañon Mountains in eastern Millard County, while the range of albicaudatus and contractus have been separated by that of lenis. T. b. lenis has the majority of its affinities with aureiventris which is an inhabitant of the western mainland of this ancient lake. An understanding of the history of the Sevier River Valley will probably clarify this distribution of pocket gophers.

Specimens examined.—Total, 39, distributed as follows: Millard County: Oak City, 5,000 ft., 15; Scipio, 5,315 ft., 15. Beaver County: Beaver, 6,000 ft., 9 (M. V. Z.).

Thomomys bottae lenis Goldman

Thomomys townsendii lenis Goldman, Proc. Biol. Soc. Washington, 55:75, June 25, 1942.

Thomomys perpallidus aureus Moore, Journ. Mamm., 10:259; November 11, 1931.

Type.—Male, adult, skin and skull, No. 264805, U. S. National Museum (Biological Surveys Collection); Richfield, 5,308 ft., Sevier County, Utah; March 11, 1928; collected by A. W. Moore; X-catalogue number 28835 (after Goldman, type not seen).

Range.—Sevier River Valley from Piute County north to southwestern Juab and northeastern Millard counties, Utah.

Diagnosis.—Size large (see measurements). Color: Upper parts Cinnamon Buff mixed with black in middorsal region; sides, flanks, forearms, thighs and underparts Pinkish Buff; inguinal region, front feet, hind feet, underpart of tail and end of tail white; postauricular patches small and dusky; chin, cheeks, nose and top of head dusky. Skull: Largest of Utah gophers, massive and angular; nasals long and denticulate distally; rostrum long and relatively narrow; zygomatic arches widely spreading and heavy throughout; jugals nearly vertical; zygomatic processes of maxillae heavy and flaring out abruptly from base of rostrum; union of zygomatic process of maxilla and jugal greatly thickened; extension of premaxillae posterior to nasals long; posterior tongues of premaxillae relatively narrow; lacrimal processes small; pterygoid hamulae long; interpterygoid space moderately V-shaped, tending to be somewhat lyre-shaped in some specimens; tympanic bullae somewhat flattened, only moderately inflated ventrally; upper incisors long and narrow; molariform teeth actually large, but relatively small.

Comparisons.—Topotypes of lenis can be distinguished from those of Thomomys bottae tivius, convexus, contractus, albicaudatus, levidensis, centralis and aureiventris by the following markedly greater average measurements of males: Total length, 250 mm.; length of nasals, 15.5; zygomatic breadth, 28.3; mastoid breadth, 22.5; and length of rostrum, 18.3. Other distinguishing characters are: Zygomatic arches more widely spreading; length of zygomatic processes of maxillae greater; and relatively longer, narrower rostrum.

Remarks.—Twenty-one animals obtained from Lynndyl, Millard County, are all intergrades between lenis and aureiventris. They are like aureiventris in the shape of the zygomatic arches, and in the bowing of the parietal crests. Slight intergradation with centralis is indicated by color and the shape of the nasals. The transverse arching of the posterior part of the rostrum is indicative of some relationship with contractus. In six other characters studied they most closely approach lenis to which they are here referred.

Large size is the distinctive feature of Thomomys bottae lenis. The skulls are the largest of any species or subspecies of Thomomys found in Utah. In total length, however, these animals are no longer than the extremes found in other named races. When Goldman (1942:75) described this race as new, he referred it to the species Thomomys townsendii, but remarked that the animal from Richfield was different enough from any other form then named to merit probably full specific status. I know of no character other than size to separate Thomomys townsendii from Thomomys bottae, and since intergradation has been shown to exist between these alleged townsendii from Richfield and animals from extreme western Utah known to belong to the species bottae, lenis is here arranged as a subspecies of Thomomys bottae which name has priority over Geomys townsendii.

The range here ascribed to this race is the Sevier River Valley from Piute County as far downstream as the town of Lynndyl which is near the eastern mainland of Pleistocene Lake Bonneville. The Sevier River continues farther out into Delta Valley ultimately to empty into Sevier Lake, which at present is adjacent to the area that formerly constituted the western mainland of the aforementioned ancient lake. This watercourse may have provided a migration route in ancient times, during the fluctuations of Lake Bonneville, whereby the animals formerly of the western mainland were able to come far eastward. The animals from Lynndyl which are intergrades between lenis, an eastern mainland form, and centralis and aureiventris which are western mainland forms of Lake Bonneville lend support to this hypothesis.

Specimens examined.—Total, 26, distributed as follows: Millard County: Lynndyl, 4,796 ft., 21. Juab County: U. B. (= Yuba) Dam, 5,000 ft., 1. Sevier County: Salina, 4,575 ft., 1; Richfield, 5,308 ft., 3. (U. S. N. M.).

Thomomys bottae levidensis Goldman

Thomomys bottae levidensis Goldman, Proc. Biol. Soc. Washington, 55:76, June 25, 1942.

Thomomys perpallidus aureus Bailey, N. Amer. Fauna, 39:75, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927.

Type.—Male, adult, skin and skull, No. 191962, U. S. National Museum (Merriam Collection); Manti, 5,500 ft., Sanpete County, Utah; December 6, 1888; collected by Vernon Bailey; original number 427 (after Goldman, type not seen).

Range.—San Pitch River Valley, Sanpete County, Utah.

Diagnosis.—Size small (see measurements). Color: Upper parts and sides Cinnamon Buff, finely mixed with black along median line of back; underparts Pinkish Buff; nose, cheeks and chin grayish black; postauricular patches fairly large and grayish black; front and hind feet white (examples from type series badly stained); tail light buff but apparently white distally (the color of these specimens has apparently changed with age). Skull: Small, fairly robust; basilar length short; zygomatic arches weak, but widely spreading; tympanic bullae small; nasals short and simple distally; ventral margin of jugals convex dorsally; extension of premaxillae posterior to nasals relatively as well as actually long; posterior tongues of premaxillae relatively wide.

Comparisons.—Topotypes of levidensis differ from those of Thomomys bottae absonus as follows: Size smaller. Color: Lighter throughout. Skull: Shorter, weaker and less ridged and angular, but relatively wider.

Compared with topotypes of Thomomys bottae albicaudatus, levidensis differs as follows: Size smaller in every measurement taken. Color: Markedly lighter throughout. Skull: Smaller in every measurement taken; width relatively greater; skull smooth, weak and nonangular as opposed to ridged, robust and angular.

For comparisons with Thomomys bottae lenis and contractus see accounts of those forms.

Remarks.—The range here ascribed to levidensis is the San Pitch River Valley, which gradually merges southward into the Sevier River Valley. The latter valley in this area is inhabited by pocket gophers that belong to another subspecies, lenis. Nephi Valley to the west of San Pitch River Valley is inhabited by animals belonging to the subspecies albicaudatus. No known specimens show intergradation between lenis and levidensis, but intergradation between lenis and albicaudatus is noted in the Nephi Valley animals (see account of albicaudatus). Superficially levidensis resembles absonus in size and color, but the skulls closely resemble those of albicaudatus, except for size in which they are smaller in all measurements. T. b. albicaudatus is the most variable subspecies of T. bottae occurring in Utah, and additional material from the Sevier River Valley between San Pitch River Valley and Nephi Valley may show levidensis to be only a local variant of the highly variable subspecies, albicaudatus.

Specimens examined.—Total, 6, from the type locality.

Thomomys bottae osgoodi Goldman

Thomomys perpallidus osgoodi Goldman, Journ. Washington Acad. Sci., 21:424, October 19, 1931.

Thomomys bottae osgoodi Goldman, Proc. Biol. Soc. Washington, 48:156; October 31, 1935.

Thomomys perpallidus aureus Bailey, N. Amer. Fauna, 39:75, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927.

Type.—Male, adult, skin and skull, No. 158530, U. S. National Museum (Biological Surveys Collection); Hanksville, Wayne County, Utah; October 20, 1908; collected by W. H. Osgood; original number 3701 (after Goldman, type not seen).

Range.—Eastern Utah in the valleys of the drainage of the San Rafael, Dirty Devil and Price rivers.

Diagnosis.—Size medium (see measurements). Color: Upper parts near (e) Pale Ochraceous Buff, definitely yellow in appearance; sides Pale Ochraceous Buff; entire underparts white, with a wash of Light Buff in the pectoral and inguinal regions; top of head, nose, cheeks, and chin dusky; postauricular patches grayish black; front feet, hind feet and distal part of tail white. Skull: Fairly robust but narrow; zygomatic arches concave medially in mid-jugal region; skull moderately convex dorsally, due to swelling in region of base of rostrum; lambdoidal suture situated well ahead of posterior margin of skull, with supraoccipital forming a side shelf at posterior part of skull; interpterygoid space narrowly V-shaped; tympanic bullae well inflated ventrally; basioccipital short; nasals rounded posteriorly; molariform teeth large.

Comparisons.—Topotypes of osgoodi differ from those of Thomomys bottae absonus as follows: Size generally smaller. Color: Lighter throughout, more yellowish in appearance as opposed to buffy. Skull: Smaller in all measurements, except length of nasals, mastoid breadth, and alveolar length of upper molar series which are larger; rostrum shorter but relatively wider; zygomatic arches more robust and concave medially; palate wider; supraoccipital more bulging posteriorly; tympanic bullae more inflated ventrally; molariform teeth larger.

For comparisons with Thomomys bottae aureus and T. b. dissimilis see accounts of those forms.

Remarks.—The animals here referred to osgoodi are remarkably uniform in color, but vary widely in cranial details. Specimens from Carbon County are not typical and when more material becomes available it may prove that these animals from the northern part of the range of osgoodi will merit separation and naming. The specimens from Emery County are not typical but resemble osgoodi more than do the animals from Carbon County.

The range here ascribed to osgoodi is in that part of the eastern Utah desert that is bounded on the east by the Green and Colorado rivers, on the west by the high mountains of central Utah, on the north by the Book Cliffs and on the south by the Dirty Devil River. This area is an uninviting wasteland in which there are relatively few roads and little water. In addition, it is greatly cut up by washes and gullies which contain water only during a few weeks of the year. The continuation of this area of wasteland southward beyond the Dirty Devil River is inhabited by pocket gophers belonging to the subspecies absonus. If specimens were available they would undoubtedly show intergradation to exist between osgoodi and absonus.

Specimens examined.—Total, 14, distributed as follows: Carbon County: 1-2 mi. N Spring Glen, 6,150 ft., 2; Spring Glen, 6,200 ft., 2; 2 mi. E Spring Glen, 6,200 ft., 1. Emery County: Price River, 2 mi. SE Woodside, 4,600 ft., 2 (C. M.); Green River, 4,080 ft., 5 (M. V. Z.). Wayne County: Hanksville, 2 (U. S. N. M.).

Thomomys bottae howelli Goldman

Thomomys bottae howelli Goldman, Journ. Washington Acad. Sci., 26:116, March 15, 1936.

Type.—Female, adult, skin and skull, No. 25684, U. S. National Museum (Biological Surveys Collection); Grand Junction, 4,600 ft., Mesa County, Colorado; November 7, 1895; collected by A. H. Howell; original number 493 (after Goldman, type not seen).

Range.—In the valleys of eastern Utah, east of the Green River and north of the Colorado River.

Diagnosis and Comparisons.—Inasmuch as there is but one specimen, the holotype known, and as it was impossible to study it, the following diagnoses and comparisons are from Goldman, (1936:116).

"General characters.—A rather large, pallid subspecies with a broad, flattened cranium. Similar to the palest specimens of Thomomys bottae aureus of the San Juan River Valley, southeastern Utah, in color, but underparts more thinly overlaid with buffy white, and cranial characters, especially the broad, flat braincase, distinctive. Approaching Thomomys bottae osgoodi of the Fremont River Valley, Utah, in color, but much larger and skull widely different.

"Color.—Type (winter pelage): Upper parts in general between tilleul buff and pale olive buff (Ridgway 1912), somewhat darkened on head by a mixture of cinnamon buff and brown; a few inconspicuous dusky-tipped hairs along median line of back; muzzle dusky; ears and postauricular spots deep, contrasting black; underparts thinly overlaid with buffy white, the hairs becoming pure white to roots on inguinal region; thighs pure white to roots all around; feet white; tail buffy whitish, slightly paler below than above.

"Skull.—Similar in general to that of T. b. aureus, but braincase conspicuously broader and flatter; zygomata more widely spreading; nasals shorter; premaxillae more attenuate posteriorly; interparietal larger; audital bullae more rounded and fully inflated anteriorly; incisors short, as in aureus, but less strongly recurved. Compared with that of T. b. osgoodi the skull is much larger, with flatter braincase, shorter nasals, and posteriorly narrower premaxillae."

Remarks.—Six specimens, in the Carnegie Museum from 10 miles north of Moab, Grand County, Utah, were available for this study. They are not typical of howelli as it is diagnosed by Goldman (loc. cit.). They appear to be intergrades between howelli and osgoodi in cranial characters, but more closely resemble howelli, particularly in the flat, widened, low braincase. In color, some specimens seem to intergrade toward aureus.

The range ascribed to this form in Utah appears to be one of the most natural ones within the state since it is bounded by the Green and Colorado rivers which have formed deep rocky gorges in this region.

Specimens examined.—Total, 6, as follows: Grand County: 10 mi. N Moab, 6 (C. M.).

Thomomys bottae wahwahensis Durrant

Thomomys bottae wahwahensis Durrant, Bull. Univ. Utah, 28 (No. 4):4, August 18, 1937.

Type.—Male, adult, skin and skull, No. 1750, Museum of Zoölogy, University of Utah, Wah Wah Springs, 30 mi. W Milford, 6,500 ft., Beaver County, Utah; July 22, 1936; collected by S. D. Durrant; original number 989.

Range.—Westcentral Utah, in Wah Wah Mountains, and Pine Valley to the west of these mountains.

Diagnosis.—Size medium (see measurements). Color: Upper parts Pinkish Buff; underparts Pale Pinkish Buff with considerable admixture of gray; inguinal and pectoral regions Pale Pinkish Buff; nose and cheeks grayish black; postauricular patches small and black; front feet, hind feet and distal one-third to one-half of tail white. Skull: Flat dorsoventrally; rostrum short and wide; premaxillae broad and heavy; nasals short and straight, with no arching as viewed laterally; tympanic bullae small; space enclosed within zygomatic arches short antero-posteriorly; alveolar length of upper molar series short; molariform teeth small.

Comparisons.—From topotypes of Thomomys bottae centralis, wahwahensis differs as follows: Size smaller in every measurement taken. Color: Lighter, Pinkish Buff as opposed to Cinnamon Buff. Skull: Rostrum wider, shorter and more nearly flat; nasals straight as opposed to moderately convex; tympanic bullae smaller and less inflated ventrally; zygomatic arches more widely spreading and angular; molariform teeth smaller; extension of premaxillae posterior to nasals less.

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.

Remarks.—Wah Wah Springs, the type locality of wahwahensis, are on the summit of a low pass in the Wah Wah Mountains in the desert of west central Utah. The surrounding valleys, for many miles, as far as my investigations show, are not inhabited by pocket gophers, except the Desert Range Experiment Station of the United States Forest Service in Pine Valley to the west of these mountains. There, pocket gophers were obtained which are intergrades between centralis and wahwahensis. In five out of seven characters investigated these gophers resemble wahwahensis, to which they are here referred. Study of the topography reveals the probable means by which the animals reached this valley. The long axis of the Wah Wah Mountains is north and south, but a westward arm forms the northern boundary of Pine Valley. Around springs in this westward projecting arm workings of pocket gophers were found. With the development of water at the Desert Range Experiment Station, and subsequent improvement of forage, these animals probably came down into the valley from the springs to the north.

The terrain between the Desert Range Experiment Station in Pine Valley and Snake Creek (where centralis occurs) to the west is not inhabited by pocket gophers at present. This area, however, forms part of the southwest mainland of Pleistocene Lake Bonneville, which mainland in times past was probably suitable for pocket gophers. Since the close of the Pleistocene, aridity has rendered most of it unfit for pocket gophers, and they remain only in isolated areas where suitable environments still persist.

Specimens examined.—Total, 18, distributed as follows: Millard County: Desert Range Experiment Station, United States Forest Service, Sec. 9, T. 25 S, R. 17 W, Salt Lake Base Meridian, 6. Beaver County: Wah Wah Springs, Wah Wah Mountains, 30 mi. W Milford, 6,500 ft., 12 (2, M. V. Z.).

Thomomys bottae dissimilis Goldman

Thomomys perpallidus dissimilis Goldman, Journ. Washington Acad. Sci., 21:425, October 19, 1931.

Thomomys bottae dissimilis Goldman, Proc. Biol. Soc. Washington, 48:156, October 31, 1935.

Thomomys perpallidus aureus Bailey, N. Amer. Fauna 39:75, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927.

Type.—Female, adult, skin and skull, No. 158526, U. S. National Museum (Biological Surveys Collection); E slope Mount Ellen, Henry Mountains, 8,000 ft., Garfield County, Utah; October 15, 1908; collected by W. H. Osgood; original number 3677 (after Goldman, type not seen).

Range.—Known only from the type locality.

Diagnosis.—Size small (see measurements). Color: Upper parts Light Buff, grading over sides to nearly white on underparts; underparts lightly washed with Pale Buff, more marked in inguinal and pectoral regions; postauricular patches grayish black; nose, chin, cheeks and top of head dusky; front feet, hind feet and distal half of tail white. Skull: Small and weak; zygomatic arches long, but lying close to skull, giving it a slender appearance; supraoccipital markedly projecting posteriorly from lambdoidal suture; rostrum relatively long and narrow; nasals long; tympanic bullae well inflated ventrally, with a median ventral ridge; pterygoid hamulae weak; interpterygoid space narrowly V-shaped; upper incisors short and light in color; molariform teeth relatively large.

Comparisons.—Comparison of one topotype of dissimilis with topotypes of Thomomys bottae aureus shows it to differ as follows: Size smaller throughout. Color: Lighter dorsally and on sides, pale buff as contrasted with rich ochraceous; underparts more buffy. Skull: Smaller in every measurement taken; zygomatic arches markedly less widely spreading; braincase narrower and more vaulted; tympanic bullae with a median ventral ridge as opposed to smooth; pterygoid hamulae slenderer; interpterygoid space narrowly V-shaped as opposed to U-shaped; upper incisors smaller and lighter in color.

Compared with topotypes of Thomomys bottae absonus, dissimilis differs in the following features: Size smaller in every measurement taken. Color: Lighter throughout. Skull: Smaller in every measurement taken, except alveolar length of upper molar series which is greater; skull narrower and weaker; zygomatic arches weaker and less widely spreading; tympanic bullae more ridged on ventral surface and shorter (more rounded) in antero-posterior measurement; upper incisors shorter and narrower; molariform teeth larger.

Thomomys bottae dissimilis resembles T. b. osgoodi more than any other subspecies but differs in: Size smaller throughout. Color: Slightly darker dorsally. Skull: Smaller in every measurement taken, and slenderer; rostrum relatively longer; zygomatic arches weaker, and less widely spreading, more converging anteriorly; tympanic bullae less rounded, more ridged medioventrally; upper incisors shorter but narrower; molariform teeth smaller.

Remarks.—The Henry Mountains, in eastern Garfield County, are in the Colorado River drainage. The surrounding country is desertlike and cut by gullies and washes with sheer escarpments and precipitous draws. The type locality of dissimilis is possibly in an isolated area. Only three specimens were available to Goldman when he named dissimilis. He commented on the close resemblance to osgoodi which inhabits the country to the north. I have examined only one of the three specimens available to Goldman. Although I can see the characters that he mentioned, I am not fully convinced that dissimilis is separable from osgoodi. Two specimens from Escalante, Garfield County, are referred to absonus, but they show intergradation with dissimilis.

Specimens examined.—One (U. S. N. M.) from E slope Mount Ellen, Henry Mountains, 8,000 ft., Garfield County.

Thomomys bottae aureus Allen

Thomomys aureus Allen, Bull. Amer. Mus. Nat. Hist., 5:49, April 28, 1893.

Thomomys bottae aureus Goldman, Proc. Biol. Soc. Washington, 48:156, October 31, 1935; Benson, Univ. California Publ. Zoöl., 40:450, December 31, 1935.

Thomomys fulvus aureus Goldman, Journ. Washington Acad. Sci., 21:417, October 19, 1931; Journ. Washington Acad. Sci., 23:464, October 15, 1933.

Thomomys perpallidus aureus Bailey, N. Amer. Fauna, 39:74, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927.

Type.—No. 5243/4123. American Museum of Natural History; Bluff City, San Juan County, Utah; May 12, 1892; collected by Charles P. Rowley (after Allen, type not seen).

Range.—All of San Juan County (except extreme southwestern part) and Grand County east of the Colorado River.

Diagnosis.—Size large (see measurements). Color: Upper parts Cinnamon Buff, lighter on sides; underparts generally white, or if colored at all with only a faint wash of Light Buff; nose and chin blackish gray; top of head blackish due to admixture of black hairs; postauricular patches small and dusky; front feet and hind feet white. Skull: Long, narrow but massive; zygomatic arches not widely spreading, but heavy; jugals thick, union of jugals and zygomatic processes of maxillae thickened; rostrum long but wide; top of rostrum convex in lateral view; ascending processes of premaxillae wide and heavy; nasals thin proximally; braincase long and narrow; tympanic bullae well inflated ventrally; alveolar length of upper molar series long; molars large; pterygoid hamulae heavy; interpterygoid space U-shaped; palate arched; upper incisors long and wide.

Comparisons.—Compared with topotypes of Thomomys bottae osgoodi, aureus differs as follows: Size larger in every measurement taken, except tail which is shorter. Color: Darker throughout except on ventral surface which is lighter. Skull: Larger, longer and wider; nasals longer; rostrum wider and longer; zygomatic arches more nearly straight and heavier; ascending processes of premaxillae wider; basioccipital longer; interpterygoid space U-shaped as opposed to V-shaped; tympanic bullae larger; upper incisors longer, wider; molars larger.

Topotypical specimens of aureus can be distinguished from those of Thomomys bottae dissimilis by: Size larger throughout. Color: A trifle darker on dorsal surface. Skull: Larger in every measurement taken; zygomatic arches heavier and more nearly straight; tympanic bullae larger and more inflated ventrally; interpterygoid space U-shaped as opposed to V-shaped; alveolar length of upper molar series longer; molars larger; upper incisors longer and wider.

Topotypes of aureus differ from those of Thomomys bottae absonus as follows: Size larger in every measurement taken. Color: Darker dorsally, Light Ochraceous as opposed to Cinnamon Buff; due to admixture of gray, absonus has more of a grayish cast. Skull: Larger in every measurement taken, longer, narrower and more compact; zygomatic arches heavier; ascending processes of premaxillae wider; jugals heavier; tympanic bullae larger; interpterygoid space U-shaped rather than V-shaped; upper incisors longer and wider; molars larger.

From topotypes of Thomomys bottae planirostris, aureus can be distinguished as follows: Size larger; tail shorter. Color: Lighter throughout. Skull: Larger in every measurement taken except zygomatic breadth, extension of premaxillae posterior to nasals, and length of upper molariform series which are less; rostrum longer, wider and more convex; nasals slightly arched rather than straight; depression absent rather than present in posterior region of nasals; zygomatic arches not so widely spreading, but equally heavy.

For comparisons with Thomomys bottae alexandrae, see accounts under that form.

Remarks.—Topotypes of aureus are among the largest pocket gophers in the state. They are exceeded in total length only by T. b. lenis and are approached by T. b. aureiventris and T. b. planirostris. On the average they have the longest hind foot, body and ear. The length of the skull is second only to that of lenis as also is the length and breadth of the rostrum relative to the basilar length.

From the time of the original description of aureus in 1893 until 1930, all light colored gophers from Utah were referred to that form. Barnes (1927:100) gives the range of aureus as extending completely across southern Utah and on the west and east sides as far north as central Utah. Since 1930, forms named by E. R. Hall, W. H. Burt, E. A. Goldman and the writer have restricted the range of aureus in Utah to that part of the state east of the Colorado River.

Specimens examined.—Total, 22, as follows: San Juan County: Bluff, 3,300 ft., 22 (15, M. V. Z.).

Thomomys bottae birdseyei Goldman

Thomomys bottae birdseyei Goldman. Proc. Biol. Soc. Washington, 50:134, September 10, 1937.

Thomomys perpallidus aureus Bailey, N. Amer. Fauna, 39:75, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927.

Type.—Male, adult skin and skull, No. 161654. U. S. National Museum (Biological Surveys Collection); Pine Valley Mountains, 5 mi. E Pine Valley, 8,300 ft., Washington County, Utah; April 10, 1909; collected by Clarence Birdseye; original number 861 (after Goldman, type not seen).

Range.—High mountains and plateaus of southwestern Utah.

Diagnosis.—Size medium (see measurements). Color: Upper parts between Cinnamon and Sayal Brown, finely mixed with black in median dorsal region, grading over sides and flanks to Cinnamon on underparts; front feet, hind feet, and distal part of tail white; postauricular patches, chin, cheeks and top of head grayish black. Skull: Depressed along median line of frontals and posterior ends of nasals; region of nasofrontal suture concave ventrally; zygomatic arches heavy and widely spreading, widest posteriorly; posterior ends of nasals straight, tending to be somewhat rounded in some specimens; extension of premaxillae posterior to nasals moderate; tympanic bullae moderately inflated ventrally; basioccipital wide; interpterygoid space widely V-shaped.

Comparisons.—Topotypes of birdseyei differ from near topotypes of Thomomys bottae virgineus, from Beaverdam Wash as follows: Size larger; tail and hind foot longer. Color: Darker throughout, between Cinnamon and Sayal Brown as opposed to Cinnamon Buff. Skull: Larger in every measurement taken except extension of premaxillae posterior to nasals, and length and width of rostrum which are less; skull more depressed in nasofrontal region; zygomatic arches more widely spreading; zygomatic processes of squamosals shorter; pterygoid hamulae longer; tympanic bullae smaller and less inflated ventrally.

Among named races of T. bottae, birdseyei most closely resembles trumbullensis in size, but differs as follows: Hind foot and tail longer. Color: Lighter throughout; postauricular patches smaller and lighter. Skull: Larger; mastoid breadth less; zygomatic arches wider and more widely spreading posteriorly; median frontal depression more marked; extension of premaxillae posterior to nasals greater; tympanic bullae less inflated ventrally; molariform teeth larger.

For comparisons with Thomomys bottae planirostris see account of that form.

Remarks.—T. b. birdseyei is apparently endemic to the mountainous area of southwestern Utah in Washington and Iron counties. It intergrades with virgineus and with planirostris as described in the account of the latter.

Specimens examined.—Total, 8, distributed as follows: Washington County: Pine Valley, 1 (U. S. N. M.); Pine Valley Mountains, 5 mi. E Pine Valley, 8,300 ft., 3 (U. S. N. M.); Pine Valley campground, 6,800 ft., 1 (R. H.); 3/4 mi. E town of Pine Valley, 6,500 ft., 3 (R. H.).

Additional records.—Washington County: Hebron, 1; Mountain Meadows, 2 (Bailey 1915:75).

Thomomys bottae virgineus Goldman

Thomomys bottae virgineus Goldman, Proc. Biol. Soc. Washington, 50:133, September 10, 1937.

Type.—Male, adult, skin and skull, No. 262016, U. S. National Museum (Biological Surveys Collection); Beaverdam Creek, near confluence with Virgin River, Littlefield, 1,500 ft., Mohave County, Arizona; October 16, 1936; collected by Luther C. Goldman; original number 67 (after Goldman, type not seen).

Range.—Extreme southwestern Utah, in Beaverdam Wash, Washington County, Utah.

Diagnosis.—Size medium (see measurements). Color: Upper parts Cinnamon Buff, finely mixed with black; sides and flanks Pinkish Buff; underparts Pale Pinkish Buff; front feet, hind feet, and distal part of tail white; nose, cheeks, chin and top of head grayish black. Skull: Robust, with moderately wide zygomatic arches; zygomatic processes of maxillae wide; zygomatic processes of squamosals long; jugals concave laterally, giving the zygomatic arches the appearance of double bowing; nasals long; extension of premaxillae posterior to nasals long; tympanic bullae well inflated ventrally; pterygoid hamulae heavy; interpterygoid space widely V-shaped; molariform teeth large.

Comparisons.—For comparisons of virgineus with Thomomys bottae planirostris and T. b. birdseyei see accounts under those forms.

Topotypical specimens of virgineus can be distinguished from those of Thomomys bottae trumbullensis as follows: Size smaller. Color: Lighter throughout. Skull: Zygomatic arches less widely spreading; jugals more bowed medially; zygomatic processes of squamosals longer; extension of premaxillae posterior to nasals greater; tympanic bullae larger and more inflated ventrally; molariform teeth larger.

Compared with topotypes of Thomomys bottae centralis, virgineus differs in: Size smaller; tail shorter; hind foot smaller. Color: Deeper Cinnamon Buff, thus darker in overall appearance. Skull: Smaller, but relatively wider; zygomatic processes of maxillae heavier; region of maxillo-jugal sutures thicker; jugals more concave laterally; tympanic bullae more inflated ventrally; molariform teeth larger.

Remarks.—This pocket gopher occupies practically the same range in Utah as the large kangaroo rat Dipodomys deserti deserti Stephens. Both are found in the Beaverdam Wash. The type locality of virgineus is but a short distance down the Beaverdam Creek at Littlefield, Arizona. It intergrades with birdseyei, the mountain form to the north and east (see remarks under birdseyei). There are evidences of intergradation with planirostris of the Virgin River Valley above the narrows of the Virgin River where it cuts through the Beaverdam Mountains (see the discussion under planirostris). There are intergradational tendencies exhibited towards centralis in some specimens. Some of the animals are practically indistinguishable in color and there are intergrading cranial characters in the nasals, zygomatic arches and tympanic bullae.

Specimens examined.—Total, 20, distributed as follows: Washington County: Beaverdam Wash, 8 mi. N Utah-Arizona border, 7; Beaverdam Wash, 5 mi. N Utah-Arizona border, 2,600 ft., 13.

Thomomys bottae planirostris Burt

Thomomys perpallidus planirostris Burt, Proc. Biol. Soc. Washington, 44:38, May 8, 1931.

Thomomys bottae planirostris Hall and Davis, Proc. Biol. Soc. Washington, 47:52, February 9, 1934; Goldman, Proc. Biol. Soc. Washington, 48:156, October 31, 1935; Presnall, Zion-Bryce Mus. Bull., 2:14, January, 1938; Long, Journ. Mamm., 21:176, May 14, 1940.

Thomomys perpallidus aureus Bailey, N. Amer. Fauna, 39:75, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927; Woodbury, Ecological Monographs, 3:193, April, 1933.

Thomomys bottae centralis Hall and Davis, Proc. Biol. Soc. Washington, 47:52, February 9, 1934; Presnall, Zion-Bryce Mus. Bull., 2:14, January, 1938.

Thomomys perpallidus centralis Hall, Univ. California Publ. Zoöl., 23:445, July 8, 1930.

Thomomys bottae nicholi Goldman, Journ. Washington Acad. Sci., 28:337, July 15, 1938, type from Shivwits Plateau, 20 mi. S Wolf Hole (road to Parashonts), 5,000 ft., Mohave County, Arizona; Hardy, Ecological Monographs, 15:98, January, 1945.

Thomomys bottae trumbullensis Hall and Davis, Proc. Biol. Soc. Washington, 47:52, February 9, 1934.

Type.—Male, adult, skin and skull, No. 8395, Collection of Donald R. Dickey; Zion National Park, Washington County, Utah; May 4, 1920; collected by A. Brazier Howell; original number 2184 (after Burt, type not seen).

Range.—Valley of the Virgin River from Zion National Park west to the Beaverdam Mountains.

Diagnosis.—Size large (see measurements); tail long. Color: Upper parts Sayal Brown; underparts between Vinaceous Cinnamon and Cinnamon, grading to Pinkish Cinnamon in some specimens; nose, chin, cheeks, postauricular patches, and top of head grayish black; front feet and hind feet white; tail Pinkish Buff, with distal third white. Skull: Massive and ridged; nasals straight and flat, simple distally; dorsal surface of rostrum slightly concave at proximal end of nasals; zygomatic arches widely spreading, widest posteriorly; zygomatic processes of maxillae heavy; premaxillae broad and extending far beyond posterior end of nasals; rostrum wide and heavy; palate slightly arched; pterygoid hamulae heavy; interpterygoid space V-shaped; tympanic bullae moderately inflated ventrally, somewhat compressed laterally; upper incisors long and heavy; molariform teeth large.

Comparisons.—Compared with topotypes of Thomomys bottae birdseyei, planirostris differs as follows: Size larger, except total length which averages slightly less in females. Color: Lighter throughout. Skull: Larger in every measurement taken; more massive; rostrum wider, longer and more nearly flat; nasals straight and not inflated dorsally on distal end; premaxillae wider at posterior ends; extension of premaxillae posterior to nasals greater; zygomatic arches heavier, especially the zygomatic processes of the maxillae; posterior ends of nasals more nearly truncate as opposed to generally rounded; tympanic bullae more nearly flat and relatively smaller; upper incisors longer and heavier; interpterygoid space more narrowly V-shaped; molariform teeth much heavier.

Topotypes of planirostris differ from near topotypes of Thomomys bottae virgineus as follows: Size larger; tail and hind foot longer. Color: Slightly darker dorsally, but markedly darker ventrally; postauricular patches smaller and lighter. Skull: Larger in every measurement taken; skull more massive; nasals flat, neither arched nor swollen distally; rostrum wider; nasofrontal region flattened or concave as opposed to convex; premaxillae relatively narrower; zygomatic arches heavier, especially in the processes of the maxillae; tympanic bullae smaller and less inflated ventrally; interpterygoid space generally more narrowly V-shaped; upper incisors longer and heavier; molariform teeth larger.

From topotypes of Thomomys bottae trumbullensis, planirostris differs in: Size larger throughout; tail longer. Color: Much lighter throughout. Skull: More convex dorsally; rostrum wider and more depressed distally; extension of premaxillae posterior to nasals greater; zygomatic arches shorter, and not as widely spreading posteriorly; interpterygoid space more narrowly V-shaped; tympanic bullae smaller; upper incisors wider and longer; molariform teeth larger.

Topotypes of planirostris can be easily distinguished from those of Thomomys bottae absonus by darker color throughout and markedly larger size.

Remarks.—From the synonomy at the beginning of this account one may note that the animals here ascribed to this subspecies have had nearly as many subspecific names applied to them as there have been investigators who have written about them. Although each of the previous writers had but a small amount of material upon which to base his opinion, the diversity of opinion as to subspecific status bespeaks the instability of these animals. The present study is based upon eighty animals including additional comparative material.

All animals from Zion National Park have the characters pointed out by Burt (1931:38) in his description of this form. Farther down the Virgin River Valley towards St. George, however, some very perplexing problems of intergradation are encountered. St. George and environs may correctly be thought of as a "melting pot." Each of the fifty-seven animals studied from this region is an intergrade; some specimens combine the characters of three subspecies.

As may be seen on the distribution map, three different subspecies of Thomomys bottae occur in Washington County. Down the river, below St. George, the race virgineus inhabits the Virgin River Valley below the narrows of the Beaverdam Mountains. Because these narrows are filled with water from wall to wall during periods of high runoff, they form an effective barrier at present to migration of pocket gophers. The mountains to the north of St. George are inhabited by the dark form, birdseyei. The type locality of planirostris is on the middle reaches of the Virgin River, in Zion National Park. In addition Mount Trumbull to the south, in northern Arizona, is the locality of another subspecies, trumbullensis.

Unquestionably the easiest route of migration into the St. George area is down the Virgin River from Zion National Park; no barrier to gophers occurs between the Park and St. George. Although the animals from St. George are all intergrades, the majority of their affinities as would be expected are with planirostris from Zion National Park. The river itself is not an impassable barrier for gophers to the north and south of it, since this stream frequently changes its course, and often nearly dries up. The Virgin River Valley in Zion National Park is in the bottom of a relatively deep, narrow canyon which has sheer rock escarpments. The upper reaches of the river are inhabited by pocket gophers of another species, Thomomys talpoides.

Two specimens from St. George, north of the Virgin River, were identified as centralis by Hall and Davis (1934:52), but were stated to be intergrades between centralis, trumbullensis and planirostris. Goldman (1938:338) referred twelve specimens from St. George to nicholi, but stated that they intergraded with planirostris. Twenty-six other specimens from three miles southwest of St. George on the west side of Santa Clara Creek, about one-half mile above its confluence with the Virgin River and on its north side, like the topotypes of planirostris were taken in May and have complete, fresh summer pelage. With the exception of two specimens which show the ventral color of virgineus, these animals are indistinguishable in color from the topotypes of planirostris. A study of eleven measurements of the males of this series yield the following data: Like planirostris in four measurements, birdseyei in one, virgineus in one; intergrade between planirostris and birdseyei in two, planirostris and virgineus in two and birdseyei and virgineus in one. Corresponding measurements of the females show the animals to be: Like planirostris in four measurements, birdseyei in one, virgineus in two; intergrade between planirostris and birdseyei in two, planirostris and virgineus in one and birdseyei and virgineus in one. In eight of eleven measurements the males either are like planirostris or intergrade towards it, and the females are similarly allied to planirostris in seven out of eleven measurements. In none of the measurements was either sex referable to trumbullensis.

Intergradation was noted in still other cranial details. In the heavy, relatively straight zygomatic arches, a majority of the skulls resemble those of planirostris, although some show the elongated zygomatic processes of the squamosals that are characteristic of virgineus. Some skulls show a tendency toward birdseyei in the widely spreading posterior regions of the zygomatic arches. The nasals for the most part are as in planirostris. Intergradation between all three subspecies is shown in the extension of the premaxillae posterior to the nasals. Some skulls show the lateral concavity of the jugals which is characteristic of virgineus. The tympanic bullae are variable but on the average are intermediate between those of planirostris and birdseyei, but more as in the latter. The size of the pterygoid hamulae is like that of planirostris, but the shape of the interpterygoid space is more like that of birdseyei. The size of the molariform teeth is as in birdseyei. The incisors are intermediate between those of planirostris and birdseyei, but more like those of birdseyei.

Eighteen specimens from St. George and its environs, on the north side of the Virgin River, agree with the twenty-six specimens just described, except that they show more evidence of intergradation with birdseyei in slightly darker color, length of hind foot, length of nasals and alveolar length of the upper molar series.

One specimen from three miles south, two from two miles southwest, another from four miles southeast of St. George, and four immature animals from Short Creek Road south of the town of Virgin, all on the south side of the Virgin River, are darker than topotypes of planirostris and show intergradation with trumbullensis to the south. In size they are likewise closer to the latter race. They intergrade with trumbullensis in the size and shape of the zygomatic arches and tympanic bullae. In the majority of cranial details, however, they are like planirostris to which they are here referred.

One specimen, a skin only, from Danish Ranch, 5 miles northwest of Leeds, north of the Virgin River is an intergrade in size and color between birdseyei and planirostris, but referable to the latter.

Three specimens from the East Entrance, and three from near the east entrance to Zion National Park are much darker than topotypes of planirostris. All of these animals are in worn pelage, thus allowing a great amount of the black underfur to show, which gives a markedly darker color. The unworn hair is only slightly darker than that of the topotypes. The cranial details prove these animals to be intergrades between planirostris and trumbullensis. They resemble trumbullensis in size of tympanic bullae, extension of the premaxillae posterior to the nasals and shape of the nasals. The majority of the cranial details are as in planirostris to which they are here referred.

When Goldman (1938:337) named Thomomys bottae nicholi from northern Arizona he referred twelve specimens from St. George, Washington County, Utah, to his newly named race. He noted that the animals from this region intergrade with planirostris. I have had occasion to study one-fourth of the material available to Goldman for his original description of nicholi. For his specimens listed as from St. George, the exact locality of capture, which is so essential in this distributional study, was not given. All of the specimens that I have seen from the Biological Surveys Collection are from the south side of the Virgin River, while St. George itself is on the north side. As noted earlier in this account there are differences between the gophers from the two sides of the Virgin River in this area. Those from the north side are intergrades between birdseyei, planirostris and virgineus, while those from the south side are intergrades between planirostris and trumbullensis.

Goldman (loc. cit.) mentioned several times that the skulls of nicholi were nearly indistinguishable from, or closely resembled those of, trumbullensis. Color was the only truly diagnostic character mentioned by Goldman. My study reveals the same differences and likenesses found by Goldman, but I consider color alone insufficient basis in this instance for establishing a new subspecies, and regard Thomomys bottae nicholi as a synonym of the earlier proposed name, Thomomys bottae trumbullensis.

The animals from the south side of the Virgin River, labelled as from St. George, Washington County, heretofore referred by Goldman to nicholi, are intergrades between trumbullensis and planirostris and along with other specimens from the same place are referable to the latter race.

Specimens examined.—Total, 68, distributed as follows: Washington County: Danish Ranch, 5 mi. NW Leeds, 1; Zion National Park, 2 (M. V. Z.); Grotto Camp, Zion National Park, 4,300 ft., 6 (N. H. M. S. D.); Springdale, 3,400 ft., 4 (K. U.); near Short Creek Road, S town of Virgin, 4 (R. H.); St. George, N Virgin River, 2,950 ft., 21 (4, M. V. Z.; 8, R. H.; 9, N. H. M. S. D.); Santa Clara Creek, 3 mi. SW St. George, 2,800 ft., 26; St. George, S Virgin River, 5 (2, M. V. Z.; 3, U. S. N. M.); 2 mi. SE St. George, 2,950 ft., 2 (N. H. M. S. D.); 3 mi. S St. George, 1 (C. M.); 4 mi. SE St. George, S Virgin River, 1 (R. H.); 6 mi. S St. George, 2,700 ft., 6 (K. U.). Kane County: East Entrance Zion National Park, 5,725 ft., 3 (N. H. M. S. D.); near East Entrance Zion National Park, 5,500 ft., 3 (N. H. M. S. D.).

Additional records.—Washington County: Zion National Park, 22; Washington, 7 (Burt, 1931:39); St. George, 5; Santa Clara, 2 (Bailey, 1915:75).

Thomomys bottae absonus Goldman

Thomomys perpallidus absonus Goldman, Journ. Washington Acad. Sci., 21:425, October 19, 1931.

Thomomys bottae absonus Hall and Davis, Proc. Biol. Soc. Washington, 47:52, February 9, 1934; Goldman, Proc. Biol. Soc. Washington, 48:156, October 31, 1935.

Thomomys perpallidus aureus Bailey, N. Amer. Fauna, 39:75, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927.

Type.—Male, adult, skin and skull, No. 250016, U. S. National Museum (Biological Surveys Collection); Jacobs Pools, Houserock Valley, 4,000 ft., Coconino County, Arizona; June 7, 1931; collected by E. A. Goldman; original number 23569 (after Goldman, type not seen).

Range.—Southern Utah in Kane and Garfield counties, in the drainages of Kanab Creek, Johnson Creek, Paria River and Escalante River.

Diagnosis.—Size medium (see measurements). Color: Upper parts Ochraceous Buff mixed with dusky; sides and underparts Light Ochraceous Buff; chin, nose, cheeks and top of head grayish black; postauricular patches black mixed with buff; front feet, hind feet, inguinal region and distal third of tail white. Skull: Nasals relatively long; rostrum narrow; ascending processes of premaxillae narrow; extension of premaxillae posterior to nasals short; lambdoidal and sagittal crests poorly developed; zygomatic arches light; jugals nearly straight; palate narrow; molariform teeth small.

Comparisons.—Compared with topotypes of Thomomys bottae trumbullensis, absonus differs in: Size smaller. Color: Markedly lighter throughout. Skull: Smoother, less angular; zygomatic arches weak as opposed to robust; nasals more convex as viewed laterally; extension of premaxillae posterior to nasals less; ascending processes of premaxillae narrower; palate narrower; palatal pits shallower; rostrum narrower; molariform teeth smaller.

For comparisons of absonus with Thomomys bottae aureus see account under that form.

Among named races of Thomomys bottae, absonus most closely resembles planirostris, but can be distinguished from the topotypes as follows: Size markedly smaller. Color: Lighter, more buffy throughout. Skull: Smaller, less ridged and more nearly flat; nasals convex as opposed to flat; extension of premaxillae posterior to nasals less; width of ascending processes of premaxillae less; zygomatic arches weaker; palate narrower; alveolar length of upper molar series shorter; tympanic bullae more inflated ventrally; molariform teeth smaller and lighter.

Remarks.—One specimen from Kanab is an intergrade between trumbullensis and absonus. The majority of its characters are with absonus to which it is referred (see Hall and Davis, 1934:52). Two specimens from Escalante are intergrades between absonus and dissimilis, but are referable to absonus.

Specimens examined.—Total, 3, distributed as follows: Garfield County: Escalante, 5,258 ft., 2 (B. Y. U.), Kane County: Kanab, 4,925 ft., 1 (M. V. Z.).

Thomomys bottae alexandrae Goldman

Thomomys alexandrae Goldman, Journ. Washington Acad. Sci., 23:464, October 15, 1933.

Thomomys bottae alexandrae Benson, Univ. California Publ. Zoöl., 40:449, December 31, 1935.

Type.—Male, adult, skin and skull, No. 250969, U. S. National Museum (Biological Surveys Collection); 5 mi. SE Rainbow Lodge, near Navajo Mountain, Coconino County, Arizona; June 16, 1933; collected by E. A. Goldman; original number 23613 (after Goldman, type not seen).

Range.—In extreme southwestern San Juan County, Utah. Known only from Navajo Mountain, probably limited to the area enclosed on the north by the Colorado and San Juan rivers, on the east and west by Navajo and Piute canyons, respectively.

Diagnosis.—Size small (see measurements). Color: Upper parts Cinnamon Buff, grading over the sides to Pinkish Buff on underparts; nose and top of head grayish black; hind feet and tail white; postauricular patches large and dark. Skull: Small and not heavily ridged; zygomatic arches widely spreading but weak; zygomatic arches nearly parallel; tympanic bullae moderately inflated ventrally; palate not arched; interpterygoid space U-shaped; dentition light.

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

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

No. 191959 (U. S. N. M.) T. b. levidensis, 1; topotype

222 65 28 33.3 12.7 24.5 19.0 6.5 7.6 3.3 15.1 8.0

T. b. convexus, 6; topotypes

Av. 213 59 28 33.1 14.3 24.9 21.7 6.6 8.0 2.6 16.2 8.2

Min. 206 57 27 31.3 13.9 23.8 21.0 6.5 7.7 2.1 15.2 8.0

Max. 233 68 29 35.0 14.6 26.7 22.3 6.8 8.1 2.8 17.2 8.6

T. b. tivius, 7; topotypes

Av. 208 69 27 31.5 12.2 22.4 18.4 6.4 7.2 2.4 14.0 7.1

Min. 199 67 25 29.3 11.9 20.6 17.1 6.0 7.0 2.1 13.2 6.5

Max. 227 70 30 34.1 12.8 25.0 19.8 6.6 7.6 3.0 15.0 7.9

T. b. bonnevillei, 3; topotypes

Av. 228 70 30 35.4 13.9 26.4 21.8 6.6 8.1 3.7 17.6 8.5

Min. 221 62 30 33.6 13.2 25.4 20.5 6.5 8.1 3.4 16.1 8.2

Max. 236 79 30 37.4 14.9 28.0 22.5 6.7 8.1 4.3 18.1 8.7

T. b. sevieri, 3; topotypes

Av. 216 67 30 32.7 12.9 22.9 18.7 6.4 7.2 2.5 15.3 7.6

Min. 210 66 29 31.7 11.8 22.2 18.0 6.2 7.0 1.8 14.5 7.5

Max. 222 68 31 33.5 13.5 23.4 19.3 6.7 7.2 3.0 16.4 7.7

T. b. wahwahensis, 4; topotypes

Av. 228 66 29 34.7 13.5 25.5 20.7 6.6 7.3 2.3 15.7 8.7

Min. 210 60 26 33.0 13.1 24.6 20.1 6.5 7.0 2.2 14.9 8.5

Max. 250 78 30 37.6 14.6 27.0 21.4 6.8 8.0 2.5 17.1 9.0

T. b. planirostris, 8; topotypes (Burt, 1931:39)

Av. 238 76 32 35.6 13.8 25.9 20.4 6.6 8.5 3.7 .... 8.8

Min. 222 66 31 33.3 12.5 24.4 19.8 6.2 8.2 3.0 .... 8.3

Max. 261 83 34 38.7 15.3 27.6 21.3 7.2 8.9 4.5 .... 9.4

T. b. birdseyei, 3; topotypes

Av. 227 64 31 34.9 13.8 26.2 20.9 6.2 8.4 2.6 16.3 8.3

Min. 214 52 30 34.5 13.1 26.0 20.1 6.0 8.1 2.2 16.0 8.2

Max. 243 81 32 35.2 14.1 27.4 21.5 6.5 8.8 2.8 16.9 8.4

T. b. virgineus, 5; Beaverdam Wash, 5 mi. N Utah-Arizona Line

Av. 226 68 29 34.6 13.5 25.6 20.7 6.3 8.0 3.0 16.5 8.5

Min. 216 62 27 33.5 12.8 25.0 20.0 6.1 7.6 2.4 15.3 8.3

Max. 235 70 30 34.9 14.4 26.0 21.1 6.6 8.4 3.5 17.4 8.7

T. b. aureus, 3; topotypes

Av. 242 68 34 36.6 14.3 25.3 21.4 6.6 8.3 2.4 17.2 8.7

Min. 233 65 32 35.3 13.8 24.6 20.6 6.4 7.7 2.0 16.7 8.3

Max. 251 70 36 37.8 14.9 25.8 22.0 6.8 8.7 2.5 17.9 9.0

Measurements of Adult Males of Thomomys—Concluded

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. howelli, 5; 10 mi. N Moab

Av. 213 67 31 33.1 13.5 23.2 20.1 6.5 8.3 2.5 16.1 8.8

Min. 205 64 30 31.8 12.8 22.8 18.9 6.4 8.0 2.3 15.1 8.1

Max. 225 68 32 35.3 14.3 24.1 20.7 6.8 8.8 2.8 17.5 9.4

No. 3094 (U. U.) T. b. absonus, 1; topotype

220 71 29 32.0 13.9 22.6 19.0 6.4 7.0 1.0 15.1 7.2

No. 158529 (U. S. N. M.) T. b. osgoodi, 1; topotype

225 70 29 33.8 13.3 22.7 19.6 6.6 8.4 3.2 16.5 8.3

T. b. alexandrae, 1; topotype (Benson, 1935:450)

205 59 27 33.9 13.7 24.3 19.7 6.5 8.0 ... 15.8 8.1

Measurements of Adult Females 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, 2; topotypes (Hall, 1930:446)

Av. 212 62 30 32.4 12.9 22.9 19.4 6.7 7.4 2.8 .... ...

Min. 208 58 29 31.8 12.6 22.5 18.9 6.6 7.0 2.7 .... ...

Max. 215 65 30 33.0 13.1 23.3 19.8 6.8 7.8 3.1 .... ...

T. b. centralis, 17; topotypes (Hall, 1930:446)

Av. 214 67 29 31.8 12.6 22.1 19.0 6.6 7.6 2.7 .... ...

Min. 195 55 27 30.5 11.9 21.3 18.2 5.9 7.0 2.0 .... ...

Max. 229 75 30 33.0 13.8 23.1 20.1 7.1 7.8 3.4 .... ...

T. b. albicaudatus, 4; topotypes (Hall, 1930:446)

Av. 211 64 30 32.5 12.9 22.9 18.8 6.6 7.7 2.7 .... ...

Min. 199 55 29 31.7 11.9 21.9 18.2 6.1 7.5 2.6 .... ...

Max. 219 70 32 33.8 13.5 24.0 19.5 6.8 8.0 3.0 .... ...

T. b. robustus, 11; topotypes

Av. 199 61 27 30.6 11.7 22.6 18.8 6.4 7.6 2.6 13.9 7.4

Min. 191 56 22 29.0 10.6 21.0 18.1 6.2 7.1 2.0 12.0 7.1

Max. 207 66 29 31.6 12.2 23.6 19.8 6.7 8.0 2.9 14.7 7.9

T. b. stansburyi, 5; topotypes

Av. 202 57 28 31.1 12.1 21.9 18.7 6.5 7.7 2.6 14.5 7.4

Min. 195 56 26 29.9 10.6 21.0 17.8 6.2 7.3 2.3 13.4 6.9

Max. 210 63 30 32.7 12.8 22.4 19.5 6.8 8.0 3.0 15.2 7.7

No. 900 (U. U.) T. b. nesophilus, 1; topotype

210 65 31 31.2 12.3 23.2 19.3 6.9 8.2 2.2 15.2 7.3

T. b. minimus, 2; topotypes

Av. 178 56 25 28.2 10.6 19.7 17.4 6.1 7.0 2.3 13.1 6.7

Min. 175 54 24 28.1 10.4 19.6 17.1 6.1 7.0 2.3 13.0 6.5

Max. 181 58 25 28.2 10.8 19.7 17.7 6.1 7.0 2.3 13.2 6.8

T. b. contractus, 6; topotypes

Av. 219 68 30 33.1 12.6 23.3 19.5 6.5 7.8 2.6 15.5 7.1

Min. 208 58 29 32.2 12.0 22.2 18.9 6.4 7.6 2.3 14.2 7.0

Max. 225 73 31 34.7 13.3 25.2 20.6 6.7 8.2 3.2 17.0 7.3

T. b. levidensis, 4; topotypes

Av. 205 69 26 30.5 11.1 21.7 17.5 6.6 7.5 2.9 14.0 7.0

Min. 194 61 26 29.3 10.6 21.5 17.3 6.3 7.2 2.8 13.0 6.9

Max. 223 73 27 30.8 11.5 21.9 17.9 6.9 7.8 3.2 14.7 7.2

Measurements of Adult Females of Thomomys—Continued

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. convexus, 11; topotypes

Av. 197 57 27 29.9 12.5 21.7 19.3 6.6 7.7 2.6 14.7 7.4

Min. 182 43 26 27.9 11.2 21.0 18.8 6.2 7.1 2.1 13.3 7.1

Max. 204 63 28 30.9 13.4 22.3 19.8 7.1 7.9 3.1 15.2 7.7

T. b. tivius, 5; topotypes

Av. 203 68 27 29.5 11.1 21.1 17.8 6.5 7.2 2.4 13.5 6.8

Min. 192 63 26 28.0 10.5 20.1 17.3 6.3 7.1 2.0 12.7 6.4

Max. 215 74 30 31.3 11.4 22.9 19.0 6.7 7.5 3.0 14.2 7.2

T. b. bonnevillei, 7; topotypes

Av. 199 57 28 31.7 11.8 22.2 19.3 6.6 7.7 3.2 14.9 7.3

Min. 184 50 24 29.4 10.1 20.3 18.1 6.4 7.1 2.6 13.5 6.9

Max. 216 66 29 34.3 13.6 24.3 20.3 7.0 8.5 4.1 16.6 7.7

T. b. sevieri, 7; topotypes

Av. 205 62 28 30.2 11.8 21.6 18.0 6.4 7.0 2.7 14.2 7.1

Min. 199 54 28 29.4 11.3 20.6 17.7 6.1 6.6 2.1 13.9 6.6

Max. 212 70 29 30.7 12.6 22.1 18.6 6.8 7.4 3.0 14.7 7.6

T. b. wahwahensis, 8; topotypes

Av. 185 56 27 28.7 11.3 20.6 17.6 6.3 7.1 2.1 12.6 7.1

Min. 180 50 26 26.3 10.2 19.0 16.5 5.8 6.9 1.1 10.8 6.4

Max. 197 62 29 30.7 12.6 22.0 19.0 6.7 7.8 2.9 14.0 7.6

T. b. planirostris, 8; topotypes (Burt, 1931:39)

Av. 215 71 31 32.2 12.4 23.2 18.7 6.5 8.1 3.6 .... 7.9

Min. 205 61 30 31.5 11.8 22.3 18.1 6.4 7.5 2.8 .... 7.5

Max. 228 78 33 33.0 12.9 24.1 19.5 6.7 8.6 4.5 .... 8.1

T. b. birdseyei, 3; topotypes

Av. 220 71 29 31.6 11.8 22.7 18.6 6.1 7.4 2.4 14.7 7.5

Min. 217 68 28 31.4 11.0 22.4 18.3 6.0 7.3 1.6 13.3 7.4

Max. 223 75 30 32.0 12.8 23.0 19.1 6.2 7.4 3.0 15.3 7.5

T. b. virgineus, 4; Beaverdam Wash, 5 mi. N Utah-Arizona Line

Av. 211 64 29 31.6 12.2 22.6 19.4 5.9 7.5 3.1 15.1 7.3

Min. 202 60 27 31.3 11.3 22.4 18.8 5.8 7.3 2.4 14.4 7.2

Max. 218 68 30 32.1 12.8 22.7 20.0 6.1 7.8 3.7 15.5 7.6

T. b. aureus, 3; topotypes

Av. 226 57 31 33.2 13.3 23.8 19.8 6.7 8.2 1.9 15.3 8.2

Min. 217 54 30 32.8 12.5 23.3 19.6 6.4 8.0 1.6 14.5 8.2

Max. 233 64 31 34.0 14.2 24.4 19.8 6.9 8.4 2.0 16.4 8.3

No. 20300 (C. M.) T. b. howelli, 1; 10 mi. N Moab

202 59 28 32.4 12.3 21.1 19.2 6.4 7.9 2.4 15.8 8.3

Measurements of Adult Females of Thomomys—Concluded

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

No. 158524 (U. S. N. M.) T. b. dissimilis, 1; topotype

188 61 27 28.2 10.1 19.0 16.7 6.1 7.4 2.1 12.8 6.5

No. 158528 (U. S. N. M.) T. b. osgoodi, 1; topotype

203 61 27 29.6 11.5 .... 18.3 6.9 7.4 2.0 14.0 7.3

T. b. alexandrae, 3; topotypes

Av. 205 63 28 30.9 11.8 20.8 17.9 6.4 7.6 1.8 14.1 7.5

Min. 195 57 27 28.7 11.5 20.5 17.2 6.3 7.5 1.5 13.6 7.2

Max. 215 70 29 31.5 12.1 22.2 18.6 6.5 7.7 2.0 14.7 7.7