Melanism

Melanism is a congenital high level of melanin in an organism resulting in dark pigmentation.

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 an animal, making it appear melanistic.

Melanosis is hyperpigmentation associated with increased melanin, which occurs as part of a number of conditions, some are benign (like freckles). Others are (or can become) malignant. Some conditions are congenital and others are acquired.