Three New Beavers from Utah

By

STEPHEN D. DURRANT and HAROLD S. CRANE

University of Kansas Publications

Museum of Natural History

Volume 1, No. 20, pp. 407-417, 7 figs. in text
December 24, 1948

University of Kansas
LAWRENCE
1948


University of Kansas Publications, Museum of Natural History
Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Edward H. Taylor
Volume 1, No. 20, pp. 407-417, 7 figs. in text
December 24, 1948

University of Kansas
Lawrence, Kansas

PRINTED BY
FERD VOILAND, JR., STATE PRINTER
TOPEKA, KANSAS
1948

22-3716

[Pg 409]

Three New Beavers from Utah

By

STEPHEN D. DURRANT AND HAROLD S. CRANE

The subspecific identity of beavers from Utah seems never to have beencarefully investigated. With the exception of the name Castorcanadensis repentinus applied to animals from Zion and Parunuweapcanyons by Presnall (1938:14), all other writers from 1897 until thepresent time, have used for animals from Utah, the name combinationCastor canadensis frondator Mearns, the type of which is from Sonora,Mexico. Study of specimens of beavers from Utah, accumulated in thecollections of the Museum of Zoölogy, University of Utah, proves theseanimals to be far more variable than formerly supposed, and disclosesthe existence of three hitherto unnamed kinds, which are named anddescribed below.

We recognize the need for caution in proposing new names for Americanbeavers, because the transplanting of these animals from one watershedto another may have permitted the animals of a given area to changegenetically, say, through hybridization, and may also have altered thegeographic distribution of the several kinds. The officials of the UtahState Fish and Game Commission have assured us that such transplantshave not occurred in the areas where these three new kinds are found,and further that nowhere in the state have transplants been made fromone major drainage system to another; such transplants as have been madewere only within the same major drainage system.

The capitalized color terms used in this paper are after Ridgway, ColorStandards and Color Nomenclature, Washington, D. C., 1912. Allmeasurements are in millimeters. We are indebted to the officials of theUnited States National Museum for the loan of comparative materials.

Castor canadensis pallidus new subspecies

Type.—Female, adult, skin and skull, number 719, Museum of Zoölogy,University of Utah; Lynn Canyon, 7,500 ft., Boxelder County, Utah;September 7, 1932; collected by W. W. Newby.

Range.—Known only from the Raft River Mountains.

Diagnosis.—Size small; tail and hind foot short (see measurements).Color (type): Pale, upper parts uniformly Ochraceous-Buff; underfurSnuff Brown; underparts uniformly Light Buff, grading to LightOchraceous-Buff at base of tail; underfur Light Drab; front and hindfeet Light Ochraceous-Buff. Skull: Rostrum short; nasals broad (breadth[Pg 410]averaging 54 per cent of length), constricted posteriorly and barelyprojecting posteriorly beyond premaxillae; zygomatic arches robust, butnot widely spreading (zygomatic breadth 77 per cent of basilar length);mastoid breadth 73 per cent of zygomatic breadth; anterolateral marginof orbit narrow (6.2); occipital condyles visible from dorsal view;condylobasal length greater than occipitonasal length; upper incisorsnarrow (Orange Chrome in color); coronoid processes high and wide; cheekteeth narrow.

Measure