ranges of any of the known races of _T. bottae_. The eastern limits
extend into extreme western Utah. Specimens from Utah for the most part
are intergrades between _centralis_ and _aureiventris_, the race to the
north. Some minor intergradation is also noted between _centralis_ and
_sevieri_ and _bonnevillei_, the races to the east. Intergradation is
the expected condition because the animals belonging to _centralis_ are
at the extremes of their range in this area. The greater affinities of
these animals with _aureiventris_ is to be expected because both
_aureiventris_ and _centralis_ are forms of the western mainland of the
Pleistocene Lake Bonneville; while the races to the east, although
closest geographically, were isolated from the gophers of the western
mainland during prehistoric times by this lake. They are still isolated
and enough time has elapsed so that only vestiges of morphological
intergradation exist between _centralis_ and these eastern forms. Two
specimens from Cedar City, Iron County, are intergrades between
_Thomomys bottae wahwahensis_, _centralis_ and _planirostris_. Their
skulls are slightly convex as in _planirostris_, and the rostrum is
short and wide as in _wahwahensis_. In shape of the zygomatic arches,
length of the nasals, and color, they resemble _centralis_ to which
they are here referred.
_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 Zooelogy,
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 Zooelogy,
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 Zooelogy,
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 Canon 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 Canon
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. Zooel., 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 Zooelogy,
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 Canon
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.