Perognathus parvus (Peale, 1848) 



Great Basin Pocket Mouse 



Rodentia: Heteromyidae 



Global Rank: G5; State Rank: S2S4 



DESCRIPTION: Pocket mice are distinguished by their soft pelage, absence of spines or bristles, some- 

 what hairy soles on the hind feet, greatly developed mastoids that extend beyond the occipital plane, audi- 

 tory bullae meeting or nearly so anteriorly, and breadth of the interparietal less than the breadth of the 

 interorbital. The skull has a perforated nasal septum. Grooved upper incisors and external fur-lined cheek 

 pouches are shared by other members of the genus. Diagnostic characteristics of the Great Basin Pocket 

 Mouse include a lobed antitragus, length of the hind foot > 20 mm, occipitonasal length > 24 mm, ears not 

 clothed with white hairs, tail dark above and neither crested nor conspicuously tufted, and the presence of 

 an olivaceous lateral line on the body. The Great Basin Pocket Mouse is the largest member of the genus 

 ( 1 6.5-3 1 .0 grams); tail length is 1 1 0-1 20% of the length of the head and body. 



DISTRIBUTION: Great Basin Pocket Mice occupy almost the entire Great Basin Region of North 

 America, fi-om south-central British Columbia southward through central and eastern Washington and 

 Oregon, southern Idaho, southwestem Wyoming, most of Nevada and Utah, to northem Arizona and 

 northeast and east-central California. In Montana, Great Basin Pocket Mice are documented only fi-om 

 Beaverhead (8 locations) and Jefferson counties (1 location); the 1 999 records (this study) are the first fi-om 

 the Centennial Valley. 



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