This small rattlesnake averages under two feet long. It occurs in the pine-oak forests in mountains and volcanos Trans-Mexican Volcanic Belt at 5000 to 7800 ft elevation in the avocado capital of the world.

The Tancitaran dusky rattlesnake likely primarily consumes lizards. It is typically diurnal.

The Tancitaran dusky rattlesnake is one of two rattlesnakes categorized as endangered by the IUCN Red List. It is threatened by a fragmented and declining habitat, cartel activity, and volcanic activity. Current conservation efforts involve breeding this species in captivity.