Ramírez-Pulido, José, et al. "List of recent land mammals of Mexico." (2014). --

"Thorington and Hoffmann (2005) treated Neotamias durangae solivagus as a synonym of N. durangae durangae; nevertheless, and contrary to their usage, we treat solivagus as a species for the following reasons: 1) the morphological analysis by Levenson et al. (1985) showed that solivagus is different from, and on a linage apart from, durangae; 2) Piaggio and Spicer (2001), analyzed cytochrome oxidase subunit II and cytochrome b for specimens they identified as bulleri (= solivagus, because the sample came from Coahuila), and showed in all of their cladograms that durangae was basal to and clearly separate from their “N. bulleri solivagus”; 3) N. solivagus differs from N. durangae and N. bulleri, especially in color pattern and bacular morphology (Callahan 1980; Bartig et al. 1993; Best et al. 1993); and 4) solivagus is geographically isolated from both N. bulleri and N. durangae, and, in fact, is found in a different biogeographic region. N. solivagus is in the Sierra Madre Oriental, and N. bulleri and N. durangae occur in the Sierra Madre Occidental with the Mexican Plateau, a broad geographic barrier, separating them."