Two New Subspecies of Antelope Ground Squirrels from Utah

Many kinds of mammals reach their distributional limits in Utah. This is especially true of rodents restricted to montane or desert habitats. The diverse topography has been instrumental in developing many isolated or semi-isolated populations that have subsequently evolved into recognizable kinds. The central mountain ranges, beginning in northern and northeastern Utah, extend in a southern and southwestern direction. These mountains separate the deserts of the Lake Bonneville Basin from those of the Colorado Drainages of southern, southeastern and eastern Utah. Correspondingly, the desert areas in which antelope ground squirrels occur are also separated. In eastern and southeastern Utah, the Green and Colorado rivers, and their tributaries, with their deeply entrenched canyons, are also barriers that restrict gene flow between populations of antelope ground squirrels. In attempting to re-evaluate the effects of river systems and mountain barriers on the evolution and subspeciation of antelope ground squirrels in Utah, two populations were found that were beyond the range of variation found in the already known subspecies. These are here described as new subspecies. Acknowledgements .—I wish to thank Dr. Stephen D. Durrant of the University of Utah for his supervision and helpful suggestions; the United States Public Health Service, Microbiological Institute for financial aid during the course of this study; the following persons and institutions for the loan of specimens: John Aldrich and Viola S. Schantz, U. S. National Museum, Washington D. C.; J. Kenneth Doutt and Caroline A. Heppenstall, Carnegie Museum, Pittsburgh, Pennsylvania; Seth B. Benson, Museum of Vertebrate Zoology, University of California, Berkeley, California; Vasco M. Tanner and C. Lynn Hayward, Brigham Young University, Provo, Utah; Howard Knight, Weber Junior College, Ogden, Utah. Methods .—Comparisons are of adult specimens unless otherwise indicated. Color comparisons are of summer pelage unless otherwise stated. Capitalized color terms are those of Ridgway (color …