Taxonomy of the Chipmunks,
Eutamias quadrivittatus and Eutamias umbrinus
By
JOHN A. WHITE
The differences in anatomy and color between many species of chipmunks are subtle, and refined techniques are required to discover them. When "measuring" chipmunks taxonomically, it is necessary to use a "chipmunk scale" and not, for example, a "pocket-gopher scale." In explanation, some species of pocket gophers closely allied to each other, and even some subspecies of the same species, differ markedly in color and in size and shape of parts of the skeleton; comparable differences are not so pronounced among many species of chipmunks.
Historical Summary
Merriam (1905) was the first to show clearly that Eutamias quadrivittatus is a distinct species, and pointed out that E. amoenus operarius (= E. minimus operarius) is a small species which resembles, and is found in some areas together with, E. quadrivittatus.
Howell (1929) placed under E. quadrivittatus the following subspecies: E. q. quadrivittatus, E. q. hopiensis, E. q. inyoensis, E. q. frater, E. q. sequoiensis, and E. q. speciosus.
Hardy (1945) placed E. adsitus under E. quadrivittatus as E. q. adsitus, and Kelson (1951) placed E. umbrinus under E. quadrivittatus as E. q. umbrinus.
Johnson (1943) re-established E. speciosus as a separate species, and in California left only E. q. inyoensis in E. quadrivittatus.