Geographic Distribution of the Pocket Mouse, Perognathus Fasciatus

Part 1

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Geographic Distribution of the Pocket Mouse, Perognathus fasciatus

J. KNOX JONES, JR.

University of Kansas Publications Museum of Natural History

Volume 5, No. 29, pp. 515-526, 7 figures in text August 1, 1953

University of Kansas LAWRENCE 1953

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Robert W. Wilson

Volume 5, No. 29, pp. 515-526, 7 figures in text August 1, 1953

UNIVERSITY OF KANSAS Lawrence 1953

PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA. KANSAS 1953

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Geographic Distribution of the Pocket Mouse, Perognathus fasciatus

J. KNOX JONES, JR.

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.

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.

Part 2

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.

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