Part 3

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).

TABLE 1.--CRANIAL MEASUREMENTS OF PEROGNATHUS FASCIATUS

Column Headings: A: Sex and number of individuals averaged or catalog number B: Occipitonasal length C: Frontonasal length D: Basal length E: Mastoidal breadth G: Interorbital breadth H: Interparietal breadth I: Cranial depth J: Length of tym. bulla K: Length of maxillary tooth-row

Symbols: F: [Female] M:

========================================================================== | | | | | | | | | -----------+-------+-------+-------+-------+-----+-----+------+-----+----- | P. f. fasciatus, topotypes 6, 4 | | | | | | | | | and 2 | 23.3^5| 15.5^5| 18.4 | 12.3 | 5.3 | 4.9 | 8.7 | 7.3 | 3.3 min. | 22.9 | 14.9 | 17.8 | 12.1 | 5.1 | 4.8 | 8.6 | 7.0 | 3.2 max. | 24.2 | 16.5 | 18.9 | 12.8 | 5.5 | 5.1 | 9.1 | 7.6 | 3.4 -----------+-------+-------+-------+-------+-----+-----+------+-----+----- | P. f. olivaceogriseus, holotype 97941 | | | | | | | | | MVZ | 22.1 | 14.5 | 17.4 | 12.0 | 5.2 | 4.6 | 8.3 | 7.3 | 3.5 -----------+-------+-------+-------+-------+-----+-----+------+-----+----- | Various localities in eastern Wyoming 6, 5 | | | | | | | | | and 1 | 22.8 | 15.0 | 18.0 | 12.4^5| 5.0 | 4.9 | 8.4^5| 7.3 | 3.3 min. | 22.2 | 14.5 | 17.5 | 12.2 | 4.9 | 4.7 | 8.1 | 7.1 | 3.3 max. | 23.7 | 15.7 | 18.6 | 13.0 | 5.1 | 5.2 | 8.6 | 7.6 | 3.5 -----------+-------+-------+-------+-------+-----+-----+------+-----+----- | P. f. infraluteus, topotypes 4, 3 | | | | | | | | | and 1 | 21.9 | 14.4 | 17.3 | 12.2 | 4.9 | 5.2 | 8.2 | 6.9 | 3.4 min. | 21.4 | 14.0 | 17.1 | 11.8 | 4.9 | 4.9 | 8.0 | 6.7 | 3.3 max. | 22.4 | 14.9 | 17.4 | 12.6 | 5.0 | 5.4 | 8.5 | 7.1 | 3.5 -----------+-------+-------+-------+-------+-----+-----+------+-----+----- | P. f. litus, topotype 160599 | | | | | | | | | USBS | 22.2 | 14.7 | 17.4 | 11.9 | 5.0 | 5.0 | 8.7 | 7.0 | 3.3 -----------+-------+-------+-------+-------+-----+-----+------+-----+----- | 8 mi. SE Lost Soldier, 6700 ft., Wyoming 166866 | | | | | | | | | USBS | 22.1 | 14.6 | 17.4 | 12.0 | 5.2 | 4.5 | 8.4 | 7.1 | 3.3 -----------+-------+-------+-------+-------+-----+-----+------+-----+----- | P. f. callistus, Sweetwater County, Wyoming 10, 6 | | | | | | | | | and 4 | 23.1 | 15.1 | 18.0^8| 12.9^8| 5.2 | 4.5 | 8.7 | 7.6 | 3.4 min. | 22.7 | 14.7 | 17.5 | 12.7 | 5.0 | 4.1 | 8.5 | 7.3 | 3.3 max. | 24.4 | 15.9 | 18.9 | 13.1 | 5.4 | 4.9 | 8.9 | 7.8 | 3.5 -----------+-------+-------+-------+-------+-----+-----+------+-----+-----

LITERATURE CITED

CARY, M. 1911. A new pocket mouse from Wyoming. Proc. Biol. Soc. Washington, 24:61, March 22.

1917. Life Zone investigations in Wyoming. N. Amer. Fauna, 42:1-95, October 3.

DURRANT, S. D. 1952. Mammals of Utah, taxonomy and distribution. Univ. Kansas Publ., Mus. Nat. Hist., 6:1-549, August 10.

GOLDMAN, E. A. 1918. Five new mammals from Arizona and Colorado. Proc. Biol. Soc. Washington, 31:21-26, May 16.

MOORE, J. E. 1953. Notes on three additions to the rodent fauna of Alberta. Canadian Field Nat., 66:142-143, February 28.

OSGOOD, W. H. 1900. Revision of the pocket mice of the genus Perognathus. N. Amer. Fauna, 18:1-72, September 20.

SWENK, M. H. 1940. A study of the geographical and ecological distribution of the buffy plains pocket mouse (Perognathus flavescens flavescens), with description of a new subspecies from Nebraska. Missouri Valley Fauna, 3:1-8, June 5.

University of Kansas Museum of Natural History, Lawrence, Kansas. Transmitted, April 20, 1953.

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