A New Piñon Mouse (Peromyscus truei) from Durango, Mexico

In the late summer of 1949 a modest field party trekked eight miles northeast of Durango, Mexico, where the volcanic lava rocks hide a surprisingly rich mammal community. Among the specimens gathered was a series of tiny piñon mice that stood out for their unusually dark, smoky coats and subtle orange‑buff tones on the sides. Their appearance hinted at something more than a simple regional variation, prompting a closer look.

Back at the university museum, the researcher measured skulls, ears, and tails, comparing these newcomers with known relatives from nearby valleys and distant Mexican locales. The detailed analysis revealed consistent differences in coloration, ear length, and cranial features, especially inflated auditory bullae and a distinctive interparietal shape. These traits were enough to justify recognizing the lava‑dwelling population as a new subspecies, christened Peromyscus truei erasmus.

The study not only adds a new name to the catalog of North American rodents but also underscores how isolated habitats can foster hidden diversity. Listeners will get a glimpse into the meticulous work of field collection, laboratory measurement, and the excitement of naming a creature that has lived unnoticed for decades.