RANGE MAP

The Tancitaran dusky rattlesnake is a small montane species similar in many respects to the other small, Mexican montane species such as Crotalus aquilus, Crotalus lepidus, and Crotalus triseriatus.

Description:
Crotalus pusillus is remarkably similar to the dusky rattlesnake (Crotalus triseriatus) in appearance with the only minor differences separating the two. The body color is mostly gray but may be brownish. Up to 50 darker blotches run along the back and are joined laterally by two series of smaller blotches. A dark eyestripe often bordered by white runs from the eye back to the back of the head. The top of the head is often adorned with a pair of occipital blotches or spots and the rest of the head may be marked with various smaller blotches.

dorsal scale rows	ventrals		subcaudals		supralabials	infralabials
23-25		152-162		28-33	11-13	10-13
		150-162		25-29

Length:
The Tancitaran dusky rattlesnake is a small species with adults averaging 40 - 50 cm in length. The maximum length for this species is less than 70 cm.

Range:

Mexico:

disjunct populations in southern Jalisco and northwestern Michoacán.

Habitat:
The Tancitaran dusky rattlesnake is found in pine-oak forests.

Reproduction:
Nothing is known about the reproductive biology of this species.