The mammal, a desert shrew, actually was caught nearly 40 years ago in the Santa Rita Mountains, but was not identified as a new species until recently, when genetic testing confirmed the finding.
Robert Baker, now a professor at Texas Tech University, said he caught the animal when he was a graduate student at the University of Arizona. Baker has named the species Notiosorex cockrumi in honor of one of his professors, E. Lendell Cockrum.
The N. cockrumi shrew weighs only as much as a penny and is about the length of two AAA batteries. Only two other Arizona mammals are smaller: the dwarf shrew, found at high elevations in central and northern parts of the state, and the Western Pipistrelle bat.