Middle American indigo snake

The Middle American indigo snake ("Drymarchon melanurus"), also known commonly as the blacktail cribo, is a species of large, nonvenomous, snake in the family Colubridae. The species is endemic to the southwestern United States, Mexico, Central America, and northern South America. In addition to the nominotypical subspecies, it has four other recognized subspecies, including "D. m. erebennus" commonly known as the Texas indigo snake.
Description.
"D. melanurus" is a large species that can grow to a total length (including tail) of to over . This species has predominantly olive-brown glossy dorsal scales evolving to black at the tail. The underside is a lighter olive-yellow, olive-tan color.
"D. melanurus" has distinctive dark markings round the eyes, a vertical dark slash just behind the jaw. and a heavy diagonal dark slash on both sides of the neck.
The subspecies "D. m. erebennus" is predominantly solid black, though there can be lighter shaded variations.
Geographic range and habitat.
The geographic range of "D. melanurus" extends from southern Texas southwards through the Gulf Coast of Mexico, the Yucatan peninsula, Guatemala and Belize. On the Pacific coast its range extends from Sinaloa in Mexico, southward to Guatemala, as far as Colombia, Venezuela and Ecuador. Its elevational distribution goes from near sea level up to around 1,900 m asl (6,230 feet).
The subspecies "D. m. erebennus" is found in southern Texas and southwards into Mexico as far as Veracruz.
Subspecies.
There are five subspecies of "D. melanurus" which are recognized as being valid, including the nominate subspecies.
"Nota bene": A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than "Drymarchon".