Melanism

Melanism is the congenital excess of melanin in an organism resulting in dark pigment.

Pseudomelanism, also called abundism, is another variant of pigmentation, identifiable by dark spots or enlarged stripes, which cover a large part of the body of the animal, making it appear melanistic.

The morbid deposition of black matter, often of a malignant character causing pigmented tumors, is called melanosis.