resembles tivius, a small, dark, mountain form from central Utah. Size
and color are almost the same but _stansburyi_ differs in: Tail
shorter; hind foot averaging slightly longer. Skull: Generally larger
in every measurement taken; zygomatic arches shorter; width across
alveolar processes of maxillae greater; zygomatic arches more widely
spreading, and widest in extreme posterior region rather than in region
of jugal-squamosal suture.
_Remarks._--The Stansbury Mountains are separated from the Oquirrh
Mountains by the Stockton Bar, and from the Onaqui Mountains, which are
in reality a continuation of the Stansbury Mountains, by only a low
pass. Pocket gophers from Clover Creek, Onaqui Mountains and Little
Valley, Sheeprock Mountains, although intergrades between _robustus_
and _albicaudatus_ are dark in color like _stansburyi_. These
intergrades are large, dark colored, and have heavy, ridged, angular
skulls. It appears that _stansburyi_ is a mountain subspecies derived
from _albicaudatus_ of the valley. It would be instructive to
artificially transplant gophers from mountains to valleys, and _vice
versa_, so as to reveal what effects if any on the animals' morphology
the environment might have in one or a few generations. Gophers are
well known to be very plastic, and such an experiment as suggested
might call for modification of the view, held here, that the
differential features of gophers from South Willow Creek and, say,
Bauer, are hereditary.
_Specimens examined._--Total, 11, from the type locality.
=Thomomys bottae albicaudatus= Hall
_Thomomys perpallidus albicaudatus_ Hall, Univ. California
Publ. Zooel., 32:444, July 8, 1930; Univ. California Publ.
Zooel., 37:3, April 10, 1931.
_Thomomys bottae albicaudatus_ Goldman, Proc. Biol. Soc.
Washington, 48:156, October 31, 1935; Durrant, Bull. Univ.
Utah, 28 (No. 4):5, August 18, 1937.
_Thomomys perpallidus aureiventris_ Hall, Univ. California
Publ. Zooel., 37:3, April 10, 1931.
_Type._--Male, adult, skin and skull, No. 43971, Museum of Vertebrate
Zooelogy, University of California; Provo, 4,510 ft., Utah County, Utah;
October 17, 1929; collected by Annie M. Alexander; original number 506.
_Range._--From the area between the Great Salt Lake and the Wasatch
Mountains south along the western margin of the central mountains of
the state to the Sevier River, in Juab County, west into Tooele County
to the Onaqui and Sheeprock mountains.
_Diagnosis._--Size medium (see measurements); claws on front feet
medium. Color: Upper parts near (13''''_n_) Black, grading over sides
and flanks to Pinkish Cinnamon on underparts; chin, nose, top of head
and postauricular patches black; front feet, hind feet and distal third
to half of tail white. Skull: Angular and ridged; zygomatic arches
moderately wide spreading, widest posteriorly; paroccipital processes
weak; zygomatic processes of maxillae convex anteriorly; lacrimal
processes small and peglike; jugals convex dorsally on ventral surface;
nasals short, rounded distally and truncate proximally; parietal crests
bowed in, in two places; interpterygoid space broadly V-shaped.
_Comparisons._-For comparisons of _albicaudatus_ with _Thomomys bottae
aureiventris_ and _centralis_ see accounts of those forms.
Topotypes of _albicaudatus_ are dark colored and can be distinguished
from those of _Thomomys bottae birdseyei_, _tivius_, _stansburyi_ and
_contractus_ which are also dark forms, by larger size and larger, more
robust skulls (see accounts of those forms). It can be distinguished
from the remainder of the known subspecies of _Thomomys bottae_ in Utah
by darker color and by cranial details (see accounts of those forms).
_Remarks._--The range of _albicaudatus_ is larger than that of any
other race of _Thomomys bottae_ limited to Utah. Specimens are
available from thirty localities which represent widely varied habitats
and environments. This subspecies consists of many highly variable
local populations, and the marginal populations intergrade freely with
adjacent races. In many populations, it is really difficult to
recognize the relationships on account of the great variation, and one
is frequently tempted to name some of them as distinct. Careful study
of the large number of specimens has enabled me to recognize diagnostic
characters common to all of these variable populations. The animals
range from large and dark at the north to small and light at the south.
The Jordan River bisects Salt Lake County from north to south. Pocket
gophers were taken at nine places east of the river, and at three
places west of it.
Gophers from Salt Lake City and environs (east of the river) vary in
color from almost black to dark cinnamon. Specimens from Draper, which
locality is likewise east of the river, are uniformly lighter, but also
vary in color. The skulls of animals from both localities are
indistinguishable from each other and closely resemble those of
topotypes. Specimens from the west side of the river, from Riverton,
two miles west of Murray and Rose Canyon, Oquirrh Mountains, all are
lighter in color than topotypes. The color varies from darkest at the
north at Murray to lightest at the south at Riverton. This is exactly
the reverse of what would be expected since Riverton is the locality
geographically nearest to the type locality, Provo. The skulls are
quite uniform and are all referable to _albicaudatus_. The Jordan River
may be one factor which causes this lack of uniformity between the
animals from the two sides of the river. Davis (1939:56-57) states that
rivers are not barriers to movement of pocket gophers where the river
completely freezes over and has the ice covered with thick snow.
Although the Jordan River does occasionally freeze over, it is never
frozen for more than a few days at a time, and snow in this area does
not last for long periods. The material at hand indicates that the
gophers from both sides of the river are referable to the same
subspecies _albicaudatus_. The animals from the east side of the river
are in the aggregate of characters the most typical of _albicaudatus_
of any in the entire range. Those from the west side of the river,
although definitely referable to _albicaudatus_ do show some
intergradation with _Thomomys bottae robustus_, the subspecies to the
west.
The specimens from Bauer, Tooele County, are relatively uniform in
color, and are considerably lighter than topotypes of _albicaudatus_.
Their upper parts vary from Sepia to Saccardo's Umber as compared with
near (13''''_n_) Black of the topotypes. The sides and underparts are
lighter, due primarily to much less black in the underfur. They average
slightly longer in total length, but shorter in hind foot. All cranial
measurements are slightly smaller than in topotypes of _albicaudatus_.
The shape of the skull closely resembles that of _albicaudatus_,
although the rostrum, nasals, upper incisors and posterior tongues of
the premaxillae tend to be narrower. This narrowness indicates
intergradation with _Thomomys bottae stansburyi_, the race nearest to
the west. These animals are in the majority of characters referable to
_albicaudatus_.
Bauer is situated in extreme western Tooele Valley at the foot of
Stockton Bar, a low pass between the Stansbury and the Oquirrh
mountains. This valley lies to the west of the aforementioned Jordan
River. Although these gophers are definitely referable to
_albicaudatus_ they are more unlike topotypes than are the animals from
Riverton.
The specimens from Settlement Canyon, Oquirrh Mountains, Tooele County,
show the same characteristics as those from Bauer.
In a large series of animals from St. John, in Rush Valley, Tooele
County, the upper parts vary from black, even darker than topotypes of
_albicaudatus_, to Tawny Olive, and the underparts vary from black
through Cinnamon Buff to Pinkish Buff. Most of the animals are Cinnamon
Buff. Although variable they approach _albicaudatus_ in color. The
total length, tail and hind foot of males are longer than in topotypes
of _albicaudatus_; females differ in the same direction but only
slightly. In both sexes the zygomatic breadth is less, but the mastoid
breadth is greater than in _albicaudatus_. In size and shape of the
lacrimal processes, and the great thickening of the jugal at the
maxillo-jugal suture they approach _robustus_. They are much larger,
however, and in the majority of characters are referable to
_albicaudatus_.
What has just been said relative to the animals from St. John applies
also to those from Clover Creek in the Onaqui Mountains of Tooele
County. At the latter locality the tendencies towards _robustus_ are
accentuated. This is to be expected, since this locality is midway
between St. John and the type locality of _robustus_. All characters
considered, these animals are all referable to _albicaudatus_.
The animals from Little Valley, Sheeprock Mountains, Tooele County,
resemble _albicaudatus_ in color. They vary on the upper parts from
near (1) Sepia to Clay Color, and ventrally from nearly black to
Pinkish Buff. They are markedly smaller in every measurement taken,
except zygomatic and mastoidal breadths, and extension of premaxillae
posterior to nasals. This relatively greater breadth indicates
intergradation with _robustus_ to the west. These gophers are smaller
in most measurements than any other population referred to
_albicaudatus_. This is understandable because gophers from mountains
usually are smaller and have weaker, smoother skulls than animals from
low lands. Although approaching _robustus_ in size and in some
aforementioned cranial details, the aggregate of characters including
color, make these animals referable to _albicaudatus_.
The animals from Fairfield, Utah County, are closer geographically to
the type locality of _albicaudatus_ than any other series, but
morphologically are the least like topotypes. At first glance one is
struck with the differences. They are uniformly Clay Color above, with
Cinnamon Buff sides and flanks and Pinkish Buff underparts. Their color
closely approaches that of _robustus_ to the west which has Cinnamon
Buff on the upper parts. Examination of eleven measurements of males
and the same number for females, shows that the animals are nearest to
_robustus_ in two measurements, to _albicaudatus_ in 12, distinct in 7
and intermediate in one. The general appearance of the skull is
intermediate between that of the two above mentioned forms. The
differences from _albicaudatus_ in size and color may be correlated
with the differences in soil at Fairfield and Provo. At Fairfield the
soil is light-colored clay, but at Provo it is sandy and darker.
Although they are intergrades between _robustus_ and _albicaudatus_,
the animals are referred to the latter race. Utah Lake and its outlet,
the Jordan River, make a partial barrier between populations at
Fairfield and at the type locality at Provo. During Pleistocene times,
when Lake Bonneville was present it formed a complete barrier. Enough
time has evidently elapsed since the disappearance of this lake to
allow _albicaudatus_, the mainland form, to expand its range to the
west. Intergradation has taken place, with the result that the animals
from Fairfield, although unstable, agree with the mainland form,
_albicaudatus_, in a majority of their characters.
Pocket gophers were taken at four localities from north to south in
eastern Juab County. They range in color from Ochraceous Tawny on the
upper parts and Cinnamon Buff on the underparts to shades that are
slightly lighter. All are much lighter than topotypes of
_albicaudatus_. The general configuration of the skull is the same as
that of _albicaudatus_, and this is especially true in the females. In
the narrower rostrum and weaker dentition they approach _contractus_,
but are distinctly lighter colored. Hall (1931:3) referred one specimen
from Nephi, Juab County, to _Thomomys bottae aureiventris_. Since that
time _Thomomys bottae lenis_ which has some affinities with
_aureiventris_ has been described (see account of _contractus_). The
large series now available from Nephi and nearby localities do show
some intergradation with _lenis_, in that four characters are more as
in _lenis_ and _contractus_ and seven characters are more as in
_albicaudatus_. Although differing markedly in many respects from
topotypes of _albicaudatus_ they fit the aforementioned concept of this
subspecies, and are being treated as a variable local population of it.
Provo is the locality listed for specimens which were available to
naturalists from 1875-1877. To these specimens the following names were
applied: _Thomomys talpoides bulbivorus_ Coues (1875:256; 1877:627) and
_Thomomys talpoides umbrinus_ Coues and Yarrow (1875:112). Possibly
these names were applied to the animals currently known as _Thomomys
bottae albicaudatus_ which does occur at Provo. Without the opportunity
to examine the actual specimens, which so far as I know are no longer
in existence, I cannot exclude the possibility that the locality
designation "Provo" was used in a general sense to include pocket
gophers taken a few miles to the eastward of Provo, where it is known
that pocket gophers of only the species _Thomomys talpoides_ (current
terminology) occur.
_Specimens examined._--Total, 239, distributed as follows:
_Davis County_: Bountiful, 4,500 ft., 1. _Salt Lake County_:
Salt Lake City and environs, 4,300 ft., 51; 2 mi. W Murray,
4,300 ft., 6; Riverton, 4,300 ft., 11; Draper, 4,500 ft., 7;
Rose Canyon, Oquirrh Mountains, 5,650 ft., 4. _Tooele
County_: Bauer, 4,500 ft., 30; Settlement Creek, Oquirrh
Mountains, 6,500 ft., 1; St. John, 4,300 ft., 28; Clover
Creek, Onaqui Mountains, 5,500 ft., 15; Vernon, 4,300 ft., 2
(U. S. A. C.); Little Valley, Sheeprock Mountains, 5,500
ft., 20. _Utah County_: Fairfield, 4,800 ft., 24; Provo,
4,400 ft., 20 (8, B. Y. U.; 12, M. V. Z.). _Juab County_:
Neff Farm, 4 mi. N Nephi, 5,000 ft., 2 (1, R. H.); Nephi,
5,000 ft., 1 (M. V. Z.); 2 mi. S Nephi, 4,700 ft., 14; 7 mi.
SW Nephi, 6,000 ft., 2.
=Thomomys bottae bonnevillei= new subspecies
_Type._--Male, adult, skin and skull, No. 3576, Museum of Zooelogy,
University of Utah; Fish Springs, 4,400 ft., Juab County, Utah; June 8,
1940; collected by S. D. Durrant; original number 1955.
_Range._--Known only from the type locality.
_Diagnosis._--Size medium (see measurements); claws on front feet
small. Color: Entire dorsal surface Warm Buff; sides near (_e_)
Cinnamon Buff, underparts near (16") Pale Pinkish Buff; inguinal
region, front and hind feet and distal part of tail white: top of head,
nose and cheeks grayish black; postauricular patches small and grayish
black; ears small, pointed and with heavily pigmented pinnae. Skull:
Angular, short and wide; nasals of medium length, narrow proximally but
widely flared distally; interparietal small; lambdoidal suture concave
towards the interparietal; zygomatic arches uniformly widely spreading;
interpterygoid space widely V-shaped; extension of premaxillae
posterior to nasals long; lambdoidal crest well developed.
_Comparisons._--From topotypes of _Thomomys bottae aureiventris_,
_bonnevillei_ differs as follows: Size smaller, hind foot shorter.
Color: Upper parts and sides lighter; underparts pale buff rather than
"gold." Skull: Shorter and relatively wider; rostrum wider and heavier;
zygomatic arches relatively wider and more massive, with greatest width
posteriorly instead of anteriorly; interpterygoid space widely V-shaped
rather than lyre-shaped; thickening at union of jugal and zygomatic
process of maxilla less developed; anterior palatine foramina larger;
nasals shorter and more markedly flared distally; zygomatic breadth
relatively, and mastoidal breadth actually, wider; extension of
premaxillae posterior to nasals greater; tympanic bullae more inflated
ventrally; upper incisors wider.
From near topotypes of _Thomomys bottae centralis_, from 1 mile east of
Garrison, Millard County, Utah, _bonnevillei_ differs as follows: Size
smaller; hind foot and tail shorter. Color: Generally darker above and
lighter below; top of head darker; postauricular patches smaller and
lighter. Skull: Shorter and wider (zygomatic breadth expressed in
percent of basilar length being, in males, 74.5 in _bonnevillei_ and
71.5 in _centralis_); interpterygoid space more widely V-shaped;
interparietal smaller, and more triangular; nasals shorter and much
more dilated distally, as well as more constricted proximally; lacrimal
processes smaller and less globuse at tips; temporal fossae larger;
braincase and entire dorsal surface of skull more nearly flat;
lambdoidal suture convex posteriorly as opposed to nearly straight;
tympanic bullae more inflated ventrally.
Comparisons of _bonnevillei_ with the type and type series of _Thomomys
bottae wahwahensis_ show them to be of approximately the same size, but
to differ as follows: Color: Slightly darker above and lighter below;
postauricular patches smaller and lighter. Skull: Larger in every
measurement taken, except breadth of rostrum which is smaller; skull
not as flat; tympanic bullae more inflated ventrally; nasals and
rostrum longer; extension of premaxillae posterior to nasals greater;
interparietal smaller and more triangular; zygomatic arches more bowed
out laterally; jugals heavier; interpterygoid space more widely
V-shaped; upper incisors less massive.
The characters that distinguish _bonnevillei_ from _Thomomys bottae
albicaudatus_ are: Size smaller. Color: Markedly lighter throughout.
Skull: Shorter and wider; mastoid and zygomatic breadths greater;
rostrum narrower but shorter; angle between rostrum and zygomatic
processes of maxillae less; interparietal smaller and more triangular;
extension of premaxillae posterior to nasals greater; upper incisors
shorter, narrower and more recurved.
_T. b. bonnevillei_ is indistinguishable in color from _Thomomys bottae
convexus_, but differs from it in the following features: Size larger
in nearly every measurement taken. Skull: Flattened dorsally as opposed
to convex; zygomatic arches longer and weaker; jugals more nearly
perpendicular; tympanic bullae larger; upper incisors longer; alveolar
length of upper molar series the same, but molars narrower; rostrum
longer but nasals shorter; extension of premaxillae posterior to nasals
greater.
Topotypes of _bonnevillei_ can be distinguished from those of both
_Thomomys bottae tivius_ and _stansburyi_ by being larger in every
measurement taken, by markedly lighter color throughout, and by ridged,
massive, angular skulls rather than smooth, weak, nonangular skulls.
The races closest geographically to _bonnevillei_ are _Thomomys bottae
robustus_ and _T. b. sevieri_. Compared with topotypes of _robustus_,
_bonnevillei_ differs in: Size larger. Color: Lighter throughout.
Skull: Larger, although not as compact; zygomatic arches more widely
spreading; jugals lighter; lacrimal processes not as prominent;
zygomatic processes of maxillae not as robust; nasals more flared
distally; extension of premaxillae posterior to nasals greater;
alveolar length of upper molar series longer; molars larger; upper
incisors longer, wider and darker in color; when placed ventral side
down on a surface, the dorsal face of a skull of _robustus_ is
approximately parallel to the surface, whereas one of _bonnevillei_
dips down in the occipital region.
_T. b. sevieri_ can be easily distinguished from _bonnevillei_ by being
smaller in every measurement taken, darker in color, and by small,
weak, smooth skulls as opposed to large, robust, ridged skulls.
_Remarks._--Fish Springs, where _bonnevillei_ occurs is a marshy area
south of the barren, salt-desert country of western Utah. The source of
water is springs at the base of the north end of the Fish Springs
Mountains. Only the moist area supports pocket gophers. Specimens from
Trout Creek, Juab County, twenty-five miles to the southwest are
intergrades between _bonnevillei_ and _aureiventris_, and are referred
to the latter subspecies. The country between Fish Springs and Trout
Creek in 1937 and 1940 lacked pocket gophers; it was of the playa and
sand type. Probably _T. b. bonnevillei_ was derived from _T. b.
aureiventris_, a western mainland form of Pleistocene Lake Bonneville,
through isolation and subsequent differentiation morphologically. The
moist soils at Cane Springs, seven miles south of Fish Springs, had no
pocket gophers when visited in 1940.
_Specimens examined._--Total, 11, from the type locality.
=Thomomys bottae centralis= Hall
_Thomomys perpallidus centralis_ Hall, Univ. California
Publ. Zooel., 32:445, July 8, 1930.
_Thomomys bottae centralis_ Goldman, Proc. Biol. Soc.
Washington, 48:156, October 31, 1935; Hall and Johnson,
Proc. Utah Acad. Sci. Arts and Letters, 15:121, 1938.
_Type._--Male, adult, skin and skull, No. 41688, Museum of Vertebrate
Zooelogy, University of California; 2-1/2 mi. E Baker (1-1/4 mi. W
Nevada-Utah boundary on 39th parallel), 5,700 ft., White Pine County,
Nevada; May 30, 1929; collected by E. Raymond Hall; original number
2683.
_Range._--Extreme western Utah, in Millard, Beaver and Iron counties.
_Diagnosis._--Size medium (see measurements); tail long; claws on front
feet long. Color: Near Cinnamon Buff on upper parts, darker in
middorsal region, grading to Pinkish Buff on underparts, more
accentuated in pectoral and inguinal regions; nose, cheeks and
postauricular patches grayish black; front and hind feet and distal
half of tail white. Skull: Robust and moderately ridged; zygomatic
breadth about the same for entire length of arches; jugals vertical
posterior to middle; moderate thickening present at region of
maxillo-jugal suture; interpterygoid space narrowly V-shaped; dorsal
frontomaxillary sutures convex medially; lacrimal processes globose and
well developed; nasals long and with distal denticulations;
paroccipital processes well developed.
_Comparisons._--Compared with topotypes of _Thomomys bottae
albicaudatus_, _centralis_ differs as follows: Size larger; tail
longer; claws on front feet longer. Color: Lighter throughout, Cinnamon
Buff as opposed to near (13''''_n_) Black. Skull: Basilar length and
length of nasals greater; zygomatic breadth less; zygomatic arches
thicker at region of maxillo-jugal sutures; interpterygoid space more
broadly V-shaped; dorsal frontomaxillary sutures convex medially as
opposed to straight; paroccipital processes more developed; zygomatic
arches approximately the same width throughout as opposed to widest
posteriorly.
For comparisons with _Thomomys bottae aureiventris_ see account of that
form.
_T. b. centralis_ can be distinguished from _Thomomys bottae
bonnevillei_, _robustus_, _sevieri_ and _convexus_ by larger size
throughout and generally darker color (see accounts of those forms).
From _Thomomys bottae stansburyi_ and _tivius_, _centralis_ differs in
larger size throughout and lighter color (see accounts of those forms).