Donkioporia Kotl. & Pouz., a new genus for Poria megalopora (Pers.) Cooke

A new genus of resupinate polypores, Donkioporia Kotl. & Pouz., is proposed for the fungus chiefly known under the name of Poria megalopora (Pers.) Cooke. Since the oldest name of the species appears to be Boletus expansus Desm., the new combination Donkioporia expansa (Desm.) Kotl. & Pouz., is proposed. The genus is characterized microscopically by a trimitic hyphal system possessing both thin- and thick-walled generative hyphae with clamp-connections. The internal layer of the walls of some of the thick-walled generative hyphae gives an amyloid reaction.