They are a distinct species found in Northern Mexico especially the mountains of Nuevo Leon. John Fairey used to have them in his catalog at the Yucca-Do Nursery in Texas, but I, not sure if the nursery is still in business.
C pringlei is a shrubby species to about 6 to 8 feet with a fruit much smaller than C edulis. It is supposed to be much hardier. I always wanted to try grafting C. edulis on to see if 1) it would make a good dwarfing stock for edulis and 2) if it would impart more cold hardiness. Have never gotten around to it. Hybridization should also be interesting.