corticium is very thin and spread over the wood in patches.
"Studies of American Fungi. Mushrooms, Edible, Poisonous, etc."
George Francis Atkinson
Most of the genera of Auricularini are cosmopolitan, and the same is true of some species of Stereum, of corticium, etc.
"Fungi: Their Nature and Uses"
Mordecai Cubitt Cooke