In his "Revision of the pocket mice of the genus Perognathus," Osgood
(1900:18-20) reviewed the distribution, as then known, of _Perognathus
fasciatus_ and recognized two geographic races--_Perognathus fasciatus_
[_fasciatus_] Wied-Neuwied in eastern Montana and Wyoming and adjacent
parts of North and South Dakota, and _Perognathus fasciatus infraluteus_
Thomas, known only from the type locality at Loveland, Larimer County,
Colorado. Later, Cary (1911:61) described _Perognathus fasciatus litus_
as a pale subspecies occurring in the lower Sweetwater Valley and
adjacent parts of the Red Desert of south-central Wyoming. After 1911 no
important taxonomic contributions dealing with _Perognathus fasciatus_
appeared.
In studying the kinds of pocket mice known from Nebraska, I examined
thirteen specimens of _P. fasciatus_ from the northwestern part of the
state which did not agree satisfactorily with the descriptions of any
known subspecies of _fasciatus_. This impelled me to examine material
from the entire range of _P. fasciatus_. This examination revealed that:
(1) _Perognathus callistus_ Osgood, heretofore considered to be a full
species, should be reduced to subspecific rank under _P. fasciatus_; and
(2) specimens from eastern Wyoming and adjacent parts of Montana, South
Dakota and Nebraska represent an heretofore unrecognized subspecies.
Further investigation, however, revealed that _Perognathus flavescens
olivaceogriseus_ Swenk, described from northwestern Nebraska (Swenk,
1940:6), is not _flavescens_ but actually _fasciatus_. Since the
specimens on which Swenk's description was based were taken within the
range of this newly recognized subspecies, and since my examination of
the holotype shows it to be of the species _Perognathus fasciatus_, the
subspecific name _olivaceogriseus_ is available.
The subspecies of _P. fasciatus_ are most easily distinguished by color
of pelage, in which there is a general cline from northeast (dark) to
southwest (pale). Cranially, the subspecies are less distinct. The
skulls of _P. f. callistus_ can be distinguished from those of the other
subspecies by several differences; however, among the other four
subspecies, only minor cranial differences are evident. Individual
variation was found to be greater than secondary sexual variation.
[Illustration: FIG. 1. Distribution of the five subspecies of
_Perognathus fasciatus_. Solid symbols represent specimens examined;
circled symbols represent type localities.
Guide to subspecies
1. _P. f. fasciatus_
2. _P. f. olivaceogriseus_
3. _P. f. infraluteus_
4. _P. f. litus_
5. _P. f. callistus_
]
In connection with this study, grateful acknowledgment is made to
the following persons for the loan of specimens in their care: Dr.
H. E. Anthony, American Museum of Natural History (AMNH); Mr. Colin
C. Sanborn, Chicago Natural History Museum (CNHM); Mr. Austin W.
Cameron, National Museum of Canada (NMC); Miss Viola S. Schantz,
Biological Surveys Collection, U. S. National Museum (USBS); Dr.
Seth B. Benson, University of California Museum of Vertebrate
Zoology (MVZ); Mr. J. E. Moore, Department of Zoology, University
of Alberta (UADZ); Dr. William H. Burt, University of Michigan
Museum of Zoology (MZ); Dr. Otis Wade, University of Nebraska
Department of Zoology (UNDZ); Dr. C. Bertrand Schultz, University
of Nebraska State Museum (NSM); and to those in charge of the
collections of the Nebraska Game, Forestation and Parks Commission
(NGFPC). Specimens from the Museum of Natural History, University
of Kansas (KU), also have been used.
Capitalized color terms are those of Ridgway, Color Standards and
Color Nomenclature, Washington, D. C., 1912. Assistance with field
work to obtain specimens for the University of Kansas Museum of
Natural History is acknowledged from the Kansas University
Endowment Association and the National Science Foundation.
=Perognathus fasciatus fasciatus= Wied-Neuwied
_Perognathus fasciatus_ Wied-Neuwied, Nova Acta Phys.-Med. Acad.
Caesar. Leop.-Carol., 19:369, 1839, type from Upper Missouri
River near its junction with the Yellowstone, near Buford,
Williams County, North Dakota.
_Geographic distribution._--Southwestern Manitoba, extreme
northeastern Montana and all of North Dakota except extreme eastern
part, south through central South Dakota to the northeastern part
of Cherry County, Nebraska (see Figure 1).
_Remarks._--For comparisons with _Perognathus fasciatus
olivaceogriseus_, geographically adjacent to the southwest, see account
of that subspecies.
Specimens from the eastern part of the range of _P. f. fasciatus_ are
somewhat smaller and slightly darker than topotypes from Buford, North
Dakota. Specimens from 9 mi. SE Bainville, Johnson Lake and 3 mi. S
Medicine Lake, Montana, and from Crosby, North Dakota, are also paler
than those from farther east. At the southern limit of the range of the
subspecies, specimens from the Rosebud Agency and Minichaduza River,
South Dakota, approach _olivaceogriseus_ in pale dorsal coloration.
_Specimens examined._--Total number, 83, as follows: MANITOBA:
Aweme, 3 (USBS 2, NMC 1). Junction of Antler and Souris rivers, 1
(NMC). Oak Lake, 2 (NMC). MONTANA: _Roosevelt County_: 9 mi. SE
Bainville, 4 (MZ); Johnson Lake, 2 (USBS). _Sheridan County_: 3 mi.
S Medicine Lake, 1880 ft., 1 (KU). NEBRASKA: _Cherry County_: Ft.
Niobrara Game Reserve, 1 (NSM); Sparks, 1 (MZ); Valentine, 2
(UNDZ). NORTH DAKOTA: _Benson County_: 2 mi. W Fort Totten, 1400
ft., 3 (KU). _Bottineau County_: Bottineau, 1 (CNHM). _Burleigh
County_: 9 mi. E Bismark, 7 (MZ). _Dickey County_: Oakes, 2 (CNHM
1, USBS 1). _Divide County_: Crosby, 1 (USBS). _Kidder County_:
Dawson, 1 (USBS); 6 mi. W Steele, 6 (MZ). _McHenry County_: 1/2 mi.
E Upham, 1 (USBS). _Morton County_: 12 mi. W Mandan, 2 (MZ).
_Oliver County_: Ft. Clark, 8 (USBS). _Sargent County_: 7-2/10 mi.
E, 1-2/10 mi. S Oakes, 1200 ft., 1 (KU). _Sioux County_: Cannon
Ball, 6 (USBS). _Stark County_: 1 mi. S Dickinson, 1 (MZ); 9 mi. W
Dickinson, 3 (MZ); 2 mi. W Taylor, 4 (MZ). _Stutsman County_: 7 mi.
N Jamestown, 1 (MZ); 14 mi. W Jamestown, 1 (MZ). _Wells County_:
Bowdon, 1 (USBS). _Williams County_: Buford, 9 (USBS). SOUTH
DAKOTA: _Todd County_: Minichaduza River, 2 (USBS); Rosebud Agency,
1 (USBS). _Tripp County_: Colome, 3 (MZ). _Walworth County_: Swan
Creek, 13 mi. S Shelby, 1600 ft., 1 (KU).
=Perognathus fasciatus olivaceogriseus= Swenk
_Perognathus flavescens olivaceogriseus_ Swenk, Missouri Valley
Fauna, 3:6, June 5, 1940, type from [Little Bordeaux Creek,
sec. 14, T. 33 N, R. 48 W, 3 mi. E] Chadron, Dawes County,
Nebraska.
_Geographic distribution._--Southeastern Alberta, southeast to
eastern Wyoming and adjacent parts of South Dakota and Nebraska.
_Diagnosis._--External measurements of the holotype and average and
extreme external measurements of six adults (five males and one
female) from several localities in eastern Wyoming are,
respectively, as follows: Total length, 124, 132 (125-140); length
of tail-vertebrae, 53, 63 (59-68); length of hind foot, 16.5, 17
(17-18); length of ear, 6.5, 6.6 (6.0-7.0). Color: Upper parts
Cream Buff, lined with black and giving a pale olivaceous
appearance; lateral line near (16'd) Light Ochraceous-Buff;
postauricular patches Cream Buff; subauricular patches and
underparts white; tail indistinctly bicolor, dusky above, whitish
below. Skull: Size medium for species (see Table 1); braincase and
auditory bullae moderately inflated; interorbital region narrow;
mastoidal region broad.
_Remarks._--From topotypes of _Perognathus fasciatus fasciatus_,
geographically adjacent to the northeast, _P. f. olivaceogriseus_
differs in: Upper parts paler, especially face which is heavily washed
with buff; hind foot smaller; skull averaging slightly smaller in all
measurements taken (especially least interorbital breadth and cranial
depth), except mastoidal breadth which is slightly more and
interparietal breadth, length of tympanic bulla and length of maxillary
tooth-row which are approximately the same. From topotypes of
_Perognathus fasciatus infraluteus_, geographically adjacent to the
south, _P. f. olivaceogriseus_ differs in: Upper parts paler and less
drab; lateral line brighter and more ochraceous; underparts never buffy;
skull averaging larger in all measurements taken except interparietal
breadth and length of maxillary tooth-row which are smaller. From
topotypes of _Perognathus fasciatus litus_, geographically adjacent to
the southwest, _P. f. olivaceogriseus_ differs in: Upper parts darker;
skull, when specimens of equal age are compared, averaging larger in
mastoidal breadth, interparietal breadth and basal length. From
topotypes of _Perognathus fasciatus callistus_, _P. f. olivaceogriseus_
differs in: Upper parts slightly darker, pelage not silky, coarser in
appearance; hind foot shorter; skull averaging smaller in all
measurements taken (especially mastoidal breadth), except interparietal
breadth which is more.
Swenk (_loc. cit._) originally described _P. f. olivaceogriseus_ as a
subspecies of _Perognathus flavescens_. I have examined the holotype,
kindly made available to me by Dr. Seth B. Benson of the Museum of
Vertebrate Zoology, University of California, and the paratype, in the
collection of the University of Nebraska State Museum. Neither is _P.
flavescens_, but both are clearly specimens of _P. Fasciatus_ on the
basis of olive-gray dorsal coloration, larger over-all dimensions of the
skull, and in that the tympanic bullae do not meet anteriorly. In
addition, a third specimen from Glen, Nebraska, purported by Swenk to be
intermediate between _flavescens_ and _olivaceogriseus_, has been
examined and found to be an immature _fasciatus_.
[Illustration: FIGS. 2-7. Skulls of two species of pocket mice. All x
1-1/2. In comparison with _P. flavescens_ note that _P. fasciatus_ has
the tympanic bullae separated anteriorly and that the skull is slightly
larger in over-all dimensions.
FIGS. 2-4. _Perognathus fasciatus fasciatus_. Buford, Williams County,
North Dakota, May 6, 1910, [** Male], No. 168599 USBS.
FIGS. 5-7. _Perognathus flavescens flavescens_, Kennedy, Cherry County,
Nebraska, July 9, 1935, [** Female], No. 66883 MVZ.]
In the original description Swenk indicated the type locality as
Chadron, Dawes County, Nebraska. The locality given on the specimen
label of the holotype, however, is 5 mi. E Chadron. In addition, Swenk
(_loc. cit._), in the paragraph preceding the description of
_olivaceogriseus_, states that the holotype was actually taken on Little
Bordeaux Creek, sec. 14, T. 33 N, R. 48 W, 3 mi. E Chadron, on the farm
of L. M. Gates, who obtained the holotype. It seems best to restrict the
type locality to the place last mentioned.
Four specimens from southeastern Alberta recently reported by Moore
(1953:143) have been examined and seem best referred, among known
subspecies of _fasciatus_, to _P. f. olivaceogriseus_. They differ from
the latter in several minor cranial features and more drab back, sides
and lateral line. When adequate material is available they may prove to
be subspecifically different from _olivaceogriseus_. Moore referred
these specimens to _P. f. fasciatus_.
Specimens from extreme northwestern Nebraska, including the holotype,
are slightly darker than specimens from eastern Wyoming. A specimen from
Ft. Steele, Wyoming, shows approach to _P. f. litus_ in pale dorsal
coloration.
_Specimens examined._--Total number, 59, as follows: ALBERTA:
Foremost, 2 (UADZ). Manyberries, 1 (Alberta Dept. Pub. Health).
Medicine Hat, 1 (Alberta Dept. Pub. Health). MONTANA: _Carter
County_: Little Missouri River, 8 mi. NE Albion, 1 (USBS). _Custer
County_: Calf Creek, 2 (AMNH); 13 mi. E Miles City, 1 (MZ).
_Garfield County_: Piney Buttes, 1 (USBS). _Powder River County_:
Powderville, 2 (USBS). _Yellowstone County_: Lake Basin, 1 (USBS).
_County undesignated_: Wolf's Creek, 1 (AMNH). NEBRASKA: _Cherry
County_: 10 mi. E Gordon, 1 (CNHM); 12 mi. ESE Gordon, 2 (CNHM).
_Dawes County_: Chadron State Park, 1 (NGFPC); 1 mi. SW Chadron, 1
(NSM); Little Bordeaux Creek, 3 mi. E Chadron, 1 (MVZ); 10 mi. S
Chadron, 3 (MZ); 3 mi. SW Crawford, 1 (KU). _Sheridan County_:
Mirage Township, 1 (MZ). _Sioux County_: Glen, 1 (NSM); Monroe
Canyon, 1 (NGFPC). SOUTH DAKOTA: _Custer County_: Cheyenne River, 1
(AMNH); Elk Mountain, 4800 ft., 4 (USBS). _Meade County_:
Smithville, 1 (USBS). _Shannon County_: Corral Draw, 3 (AMNH); Pine
Ridge, 3 (CNHM 1, USBS 2). _Washabaugh County_: White River flood
plain, 7 mi. S Kadoka, 1 (MZ). WYOMING: _Campbell County_: 1-1/4
mi. N, 1/2 mi. E Rockypoint, 3850 ft., 1 (KU). _Carbon County_: Ft.
Steele, 1 (USBS). _Fremont County_: 40 mi. E Dubois, 1 (MZ). _Hot
Springs County_: Kirby Creek, 5000 ft., 1 (USBS). _Johnson County_:
6-1/2 mi. W, 2 mi. S Buffalo, 5620 ft., 4 (KU); 1 mi. WSW Kaycee,
4700 ft., 1 (KU). _Natrona County_: Casper, 1 (USBS); 1 mi. NE
Casper, 5150 ft., 1 (KU). _Platte County_: 2-1/2 mi. S Chugwater, 1
(KU). _Sheridan County_: Arvada, 2 (USBS); 5 mi. NE Clearmont, 3900
ft., 1 (KU). _Weston County_: Newcastle, 1 (USBS); 23 mi. SW
Newcastle, 4500 ft., 4 (KU).
=Perognathus fasciatus infraluteus= Thomas
_Perognathus infraluteus_ Thomas, Ann. Mag. Nat. Hist., ser. 6,
11:406, May, 1893, type from Loveland, Larimer County,
Colorado.
_Perognathus fasciatus infraluteus_, Osgood, N. Amer. Fauna, 18:19,
September 20, 1900.
_Geographic distribution._--Known only from the type locality and
from 7 mi. N Ramah, Colorado. Probably in other parts of
northeastern Colorado (see Figure 1).
_Remarks._--For comparisons with _Perognathus fasciatus olivaceogriseus_
Swenk, geographically adjacent to the north, see the preceding account
of that subspecies on page 520.
Of the seven topotypes available to me, six show various degrees of
encroachment of the color of the lateral line upon the underparts,
giving the ventral surface a buffy appearance, the "distinguishing
character" of the subspecies according to Osgood (_op. cit._:20). When
additional specimens are available, this character may be found to be
one of individual variation, although no specimens from other parts of
the range of the species have been found to exhibit it. Of the
subspecies _P. f. infraluteus_, each of the eight specimens examined by
me possesses buffy subauricular patches.
The specimen from 7 mi. N Ramah, Colorado, is slightly darker and less
drab than the topotypes and does not possess buffy underparts. The skull
of the specimen is broken but on the basis of characters of the pelage
it seems to be intermediate between _infraluteus_ and _olivaceogriseus_
and is referred to the former on geographic grounds.
_Specimens examined._--Total number, 8, as follows: COLORADO:
_Elbert County_: 7 mi. N Ramah, 1 (MZ). _Larimer County_: Loveland,
7 (USBS).
=Perognathus fasciatus litus= Cary
_Perognathus fasciatus litus_ Cary, Proc. Biol. Soc. Wash., 24:61,
March 22, 1911, type from Sun, Sweetwater Valley, Natrona
County, Wyoming.
_Geographic distribution._--Lower Sweetwater Valley and adjacent
parts of Red Desert in Carbon, Fremont, Natrona and Sweetwater
counties, Wyoming (see Figure 1).
_Remarks._--For comparisons with _Perognathus fasciatus
olivaceogriseus_, geographically adjacent to the northeast, see account
of that subspecies. From _Perognathus fasciatus callistus_,
geographically adjacent to the southwest, _P. f. litus_ differs in:
Upper parts paler with no trace of olivaceous; hind foot shorter; skull,
when specimens of equal age are compared, averaging smaller in all
measurements taken (especially occipitonasal length, mastoidal breadth,
length of tympanic bulla and cranial depth), except interparietal
breadth which is more.
No fully adult specimens of _P. f. litus_ have been available to me for
this study. Two of the three specimens mentioned by Cary in the original
description (holotype not seen) have been examined and found to possess
adult pelage, but cranially they must be classed as young adults. These
specimens are paler than those of any other subspecies of _fasciatus_
and do not have the olivaceous dorsal coloration present in other
subspecies.
_P. f. litus_ is seemingly an endemic race in the lower Sweetwater
Valley and adjacent parts of the Red Desert, Wyoming. The type locality,
recorded by Cary in the original description as "Sun, Sweetwater Valley,
Wyoming," is here placed in Natrona County on the basis of the map
(frontispiece) in Cary's (1917) "Life Zone Investigations in Wyoming."
_Specimens examined._--Total number, 9, as follows: WYOMING:
_Carbon County_: 8 mi. SE Lost Soldier, 6700 ft., 1 (USBS).
_Fremont County_: Granite Mts., 1 (MZ). _Natrona County_: 5 mi. W
Independence Rock, 6000 ft., 4 (KU); Sun, 1 (USBS); 16 mi. S, 11
mi. W Waltman, 6950 ft., 1 (KU). _Sweetwater County_: 27 mi. N
Table Rock, 1 (MZ).
=Perognathus fasciatus callistus= Osgood
_Perognathus callistus_ Osgood, N. Amer. Fauna, 18:28, September
20, 1900, type from Kinney Ranch, near Bitter Creek, Sweetwater
County, Wyoming.
_Geographic distribution._--East of the Green River in central and
southern parts of Sweetwater County, Wyoming, and adjacent parts of
Moffat County, Colorado (see Figure 1).
_Remarks._--For comparisons with _Perognathus fasciatus litus_,
geographically adjacent to the north, see account of that subspecies.
When Osgood (_loc. cit._) described _P. f. callistus_ as a full species,
he characterized it as having " ... the attractive coloration of
_fasciatus_, but softer and more delicate. Its position is evidently
between _fasciatus_ and _apache_, and its nearest relations are clearly
with the latter." He further remarked that, "Its large size immediately
separates it from _fasciatus_ which it resembles externally, especially
before maturity."
Comparison of the average and extreme external measurements of ten adult
_P. f. callistus_ from Sweetwater County, Wyoming, with adult
individuals of other subspecies of _P. fasciatus_ shows that _callistus_
does not average larger than _P. f. olivaceogriseus_ except in length of
hind foot and that it averages slightly smaller in all external
measurements than topotypes of _P. f. fasciatus_. Moreover, judging from
the accounts of Goldman (1918:24) and Durrant (1952:235), _Perognathus
apache caryi_ (the subspecies of _P. apache_ nearest to the range of _P.
f. callistus_) is significantly larger externally and has no trace of
olivaceous in the dorsal pelage.
Comparison of the skulls of _callistus_ with a skull of _Perognathus
apache apache_ from Wingate, New Mexico (USBS 137388), reveals the
following differences: Interparietal bone wider in _callistus_,
averaging 4.5 (as opposed to 4.0) and more pentagonal; lacrimal bone
shorter and stouter in _callistus_; tympanic bullae more inflated in
_callistus_; interorbital foramina larger in _callistus_; lower premolar
approximately the same size as the last lower molar in _callistus_,
approximately half the size of the last lower molar in _apache_.
Conversely, comparison of skulls of _callistus_ with those of _P.
fasciatus_ as concerns the above mentioned features reveals that they
closely resemble each other. In view of this resemblance it seems best
to arrange _callistus_ as a subspecies of _P. fasciatus_.
_P. f. callistus_ is distinct cranially from all other subspecies of _P.
fasciatus_ in the narrowness of the interparietal, the greater length of
the tympanic bulla and the greater mastoidal breadth. The fine, silky
nature of the pelage is shared, to some extent, with _P. f. litus_.
A specimen from 27 mi. N, 37 mi. E Rock Springs, Wyoming, referred to
_callistus_ resembles _litus_ in pale dorsal coloration and slightly
wider interparietal. Four immature specimens from 25 mi. N, 38 mi. E
Rock Springs, also referred to _callistus_, have extremely pale juvenal
pelage and also are judged to be intergrades with _litus_.
_Specimens examined._--Total number, 23, as follows: WYOMING:
_Sweetwater County_: 18 mi. S Bitter Creek, 6800 ft., 3 (KU);
Kinney Ranch, 21 mi. S Bitter Creek, 6800 ft., 9 (KU 7, USBS 2); 30
mi. S Bitter Creek, 2 (KU); 33 mi. S Bitter Creek, 6900 ft., 2
(KU); 32 mi. S, 22 mi. E Rock Springs, 7025 ft., 2 (KU); 25 mi. N,
38 mi. E Rock Springs, 6700 ft., 4 (KU); 27 mi. N, 37 mi. E Rock
Springs, 6700 ft., 1 (KU).