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. Zooel., 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.