The head of the malleus in Tamias is clearly more elongated than in eutamias.
"Genera and Subgenera of Chipmunks"
John A. White
Critical examination of new and old evidence reveals, nevertheless, that the subgenera eutamias and Neotamias of the genus eutamias are more closely related to one another than either is to the genus Tamias.
"Genera and Subgenera of Chipmunks"
John A. White
eutamias quadrivittatus hopiensis Merriam.
"Mammals of the Grand Mesa, Colorado"
Sydney Anderson