Crotalus morulus
Crotalus morulus, or the Tamaulipan rock rattlesnake, is a species of rattlesnake from Mexico, closely related to and previously considered a subspecies of Crotalus lepidus. The name morulus comes from the Latin word morus for mulberry in reference to their mottled patterns. As with all rattlesnakes, it is venomous.
Description
As juveniles, Crotalus morulus has a dark pattern with black blotches dorsally on a grey base, the dark colours blending between the patterns. Adults are also grey with dark-brown blotches. They are distinguished from Crotalus lepidus by this dark colouration and higher number of blotches.Their rattle is also known to be fluorescent, although more dull in adults than neonates.