North American Jumping Mice (genus Zapus)

Part 1

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UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

Volume 7, No. 4, pp. 349-472, 47 figures in text, 4 tables April 21, 1954

North American Jumping Mice (Genus Zapus)

PHILIP H. KRUTZSCH

UNIVERSITY OF KANSAS LAWRENCE 1954

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

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

Volume 7, No. 4, pp. 349-472, 47 figures in text, 4 tables Published April 21, 1954

UNIVERSITY OF KANSAS LAWRENCE, KANSAS

PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1954

25-1128

North American Jumping Mice (Genus Zapus)

Philip H. Krutzsch

CONTENTS

PAGE

Introduction 351

Materials, Methods, and Acknowledgments 352

Paleontology of the Genus 355

Relationships, Distribution, and Speciation 356

Annotated List of Specific and Subspecific Names 369

Characters of Taxonomic Worth 371

Nongeographic Variation 376

Check-List of the Species and Subspecies of the Genus Zapus 382

Genus Zapus 382

Part 2

Artificial Key to the Species of the Genus Zapus 384

Systematic Accounts of Species and Subspecies 385

Zapus trinotatus 385

Zapus princeps 394

Zapus hudsonius 420

Tables of Measurements 455

Literature Cited 466

INTRODUCTION

The jumping mice (Genus Zapus) are widely distributed over northern North America, occurring as far north as the Arctic Circle and as far south as Georgia, Missouri, Oklahoma, New Mexico, Arizona, and central California. In some years these small rodents are locally common in moist places that are either grassy or weedy; the jumping mice are notable for the much enlarged hind legs and the exceptionally long tail.

Members of the Genus as a whole have received no serious comprehensive taxonomic attention in the 54 years since Preble's (1899) revisionary work. In this time 15 new names have been proposed, mostly for subspecies, and only a few attempts have been made at grouping related named kinds.

In the present account it is aimed to record what is known concerning geographic distribution, taxonomically significant characters, and interrelationships of the known kinds as well as to provide means for recognizing the species and subspecies in the genus. In addition, attention is given to the probable center of origin of the subfamily Zapodinae and to the relationships and taxonomic positions of the genera Zapus, Napaeozapus, and Eozapus.

MATERIALS, METHODS, AND ACKNOWLEDGMENTS

The present report is based on a study of approximately 3,600 specimens that were assembled at the Museum of Natural History of the University of Kansas or that were examined at other institutions. Most of these specimens are stuffed skins with skulls separate. Skulls without skins, skins without skulls, entire skeletons, and separately preserved bacula are included as a part of the total. Almost every specimen is accompanied by an attached label, which bears place and date of capture, name of collector, external measurements, and sex.

Specimens used in the study of geographic variation were arranged by season of capture and according to geographic location; then they were segregated as to sex, and, under each sex, by age. Next, individual variation was measured in comparable samples of like age, sex, season, and geographic origin. Finally, comparable materials were arranged geographically in order to determine variations of systematic significance.

The only external measurements used were total length, length of tail, and length of hind foot; these measurements were recorded by the collectors on the labels attached to the skins. Height of the ear was not used since it was not recorded by many of the collectors.

In order to determine which cranial structures showed the least individual variation but at the same time showed substantial geographic variation, a statistical analysis was made of the 30 measurements, of cranial structures, heretofore used in taxonomic work on Zapus. The following measurements of the skull showed the least individual variation but showed some geographic variation and therefore, were used in this study. See figs. 1-3 which show points between which measurements were taken:

Occipitonasal length.--From anteriormost projection of nasal bones to posteriormost projection of supraoccipital bone. a to a´

Condylobasal length.--Least distance from a line connecting posteriormost parts of exoccipital condyles to a line connecting anteriormost projections of premaxillary bones. b to n

Palatal length.--From anterior border of upper incisors to anteriormost point of postpalatal notch. b to b´

Incisive foramina, length.--From anteriormost point to posteriormost point of incisive foramina. c to c´

Incisive foramina, breadth.--Greatest distance across incisive foramina perpendicular to long axis of skull. f to f´

Zygomatic length.--From anteriormost point of zygomatic process of maxillary to posteriormost point of zygomatic process of squamosal. d to d´

Zygomatic breadth.--Greatest distance across zygomatic arches of cranium at right angles to long axis of skull. j to j´

Breadth of inferior ramus of zygomatic process of maxillary.--Greatest distance across inferior ramus of zygomatic process of maxillary taken parallel to long axis of skull. d to e

Palatal breadth at M3.--Greatest distance from inside margin of alveolus of right M3 to its opposite. g to g´

Palatal breadth at P4.--Same as above except taken at P4. g to g´

Mastoid breadth.--Greatest distance across mastoid bones perpendicular to long axis of skull. h to h´

Breadth of braincase.--Greatest distance across braincase taken perpendicular to long axis of skull. i to i´

Part 3

Interorbital breadth.--Least distance across top of skull between orbits. k to k´

Length of maxillary tooth-row.--From anterior border of P4 to posterior border of M3. l to l´

Breadth of base zygomatic process of squamosal.--Greatest distance across base of zygomatic process of squamosal taken parallel to long axis of skull. m to m´

The baculum has a characteristic size and shape according to the species, and the following significant measurements of the structure were taken:

Greatest length.--From posteriormost border of base to anteriormost point on tip.

Greatest breadth at base.--Greatest distance across base taken parallel to long axis of bone.

Greatest breadth at tip.--Greatest distance across tip taken parallel to long axis of bone.

In the descriptions of color the capitalized color terms refer to those in Ridgway (1912). Any color term that does not have the initial letter capitalized does not refer to any one standard.

In the description of the subspecies the two sexes are treated as one because no significant secondary sexual variation was found. Only fully adult specimens of age groups 3 to 5, as defined on pages 377 and 388, have been considered.

Unless otherwise indicated, specimens are in the University of Kansas Museum of Natural History. Those in other collections are identified by the following abbreviations:

AMNH. American Museum of Natural History. CAS. California Academy of Science. CM. Carnegie Museum. Chic. AS. Chicago Academy of Science. Clev. MNH. Cleveland Museum of Natural History. LMH. Collection of Lawrence M. Huey. JKJ. Collection of J. Knox Jones, Jr. CMNH. Colorado Museum of Natural History. FM. Chicago Museum of Natural History. HM. Hastings Museum, Hastings, Nebraska. ISC. Iowa State College. MCZ. Museum of Comparative Zoology. MO. University of Missouri Museum of Zoology. MVZ. Museum of Vertebrate Zoology, Berkeley, Calif. NMC. National Museum of Canada. NGFP. Nebraska Game, Forestation, and Parks Commission. NCS. North Carolina State College. OHIO. Ohio Wildlife Research Unit, Ohio State University. OKLA. Oklahoma Agricultural and Mechanical College. PM. Provincial Museum of British Columbia. ROM. Royal Ontario Museum of Zoology. SDM. San Diego Natural History Museum. SITC. Southern Illinois Teachers College. USBS. United States Biological Surveys Collection. USNM. United States National Museum. UCM. University of Colorado Museum. UIM. University of Illinois Museum of Natural History. UM. University of Michigan Museum of Zoology. UU. University of Utah Museum of Zoology.

The species are arranged from least to most progressive, and the subspecies are arranged alphabetically.

The synonymy for each subspecies includes first a citation to the earliest available name then one citation to each name combination that has been applied to the subspecies and, finally, any other especially important references.

Marginal records of occurrence for each subspecies are shown on the maps by means of hollow circles and these localities are listed in clockwise order beginning with the northernmost locality. If more than one of these localities lies on the line of latitude that is northernmost for a given subspecies the western-most of these is recorded first. Marginal localities have been cited in a separate paragraph at the end of the section on specimens examined in the account of a subspecies. Localities that are not marginal are shown on the maps by solid black circles. Localities that could not be represented on the distribution map because of undue crowding or overlapping of symbols are italicized in the lists of specimens examined and in the lists of marginal records.

The localities of capture of specimens examined are recorded alphabetically by state or province, and then by county in each state or province. Within a county the specimens are recorded geographically from north to south. The word "County" is written out in full when the name of the county is written on the label of each specimen listed for that county, but the abbreviation "Co." is used when one specimen or more here assigned to a given county lacks the name of the county on the label.

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