The Crotalus tancitarensis, or Tancitaran rattlesnake, is a medium-sized species found in the Sierra Madre del Sur of Mexico, known for its distinctive brown or gray scales, triangular-shaped head, and warning rattle. Thriving in rocky terrains at elevations of 1,000 to 2,500 meters, this carnivorous snake primarily preys on small mammals and plays a vital role in maintaining ecological balance.