The Arizona myotis (Myotis occultus) or southwestern little brown myotis is a vesper bat species inhabiting much of the southwestern United States and central Mexico as far south as the Distrito Federal.
It was described as a new species in 1909 by American zoologist Ned Hollister. The holotype was collected near Needles, California, in 1905. Its specific name "'" is Latin for "hidden or concealed".
It is a small species with a total length of — of the total length, consists of its tail. Its fur is glossy brown with a cinnamon tint. The ventral fur and its face are paler brown.
Its range includes parts of the Southwestern United States and the Mexican state of Chihuahua. It is found in a range of elevations from near sea level to above sea level.
As of 2018, it is evaluated as a least-concern species by the IUCN. It meets the criteria for this classification because it has a wide geographic range, its range includes protected areas, and it is not likely experiencing rapid population decline.