It is endemic to Mexico and known from the Sierra Madre del Sur in Guerrero and southern Oaxaca.

[3] The specific name uno refers to uniqueness of this species among its relatives (at the time of description, genus Eleutherodactylus).

[2] Craugastor uno was described based on a single specimen (holotype), an adult female measuring 63 mm (2.5 in) in snout–vent length.

Also the patterns vary, but all individuals had three paired black dorso-lateral blotches, a white mid-dorsal stripe, and a barred upper lip surface.

[4] Craugastor uno inhabits mesic pine-oak forests[3] at elevations of 1,550–2,295 m (5,085–7,530 ft) above sea level.