is a term that refers to the black color phase of some mammals. For example, some populations of marmots are melanistic or black.
• (a.) Affected with melanism; of the nature of melanism.
An animal with excessive melanin expressed usually a black individual.
The black or dark color form of an organism.
Mel`a·nis'tic adjective Affected with melanism; of the nature of melanism. 
having an excess of melanin or black pigment.
A bird that has a surplus of dark feathers.
Tending to be black or blackish, resulting from an excess of the dark pigment melanin in the feathers.