The two prominent color forms are quite often recognized as two species, or by others as varieties; the gray or mouse colored form as A. livida Pers.
"Studies of American Fungi. Mushrooms, Edible, Poisonous, etc."
George Francis Atkinson
2287, 3714, 3851. 1229 Pers.
"Roman Society from Nero to Marcus Aurelius"
Samuel Dill
The Fuligo vaporaria Pers.
"The Myxomycetes of the Miami Valley, Ohio"
A. P. Morgan