THE GENUS ALEURODISCUS (SENSU STRICTO) IN NORTH AMERICA

Abstract

The basidiomycete genus Aleurodiscus Rabenh. ex J. Schroet. has been variously interpreted by several authors. In its broadest sense the genus comprises the cyphelloid and corticioid homobasidiomycetes with large basidiospores. Aleurodiscus (sensu lato), thus defined, presently consists of nearly 110 named species, which appear to be referable to about 75 accepted taxa.The present work is a taxonomic re-evaluation of the genus Aleurodiscus. Some attempt to establish specific limits for the North American Aleurodisci follows and the taxonomic position of Aleurodiscus (sensu stricto) is considered. Although particular emphasis has been devoted to the North American species, practically all of the previously described species of Aleurodiscus have been reviewed by the author. When most of the named species of Aleurodiscus are compared, they appear to form a natural assemblage on the basis of their spore amyloidity and marked affinity in microstructure. These species have been retained within the genus Aleurodiscus (sensu stricto) (TYPE SPECIES: A. amorphus (Pers. per Purt.: Fr.) J. Schroet.). Certain species formerly placed in Aleurodiscus belong elsewhere. These species remain either to be reallocated into other recognized genera or to be relegated into new genera. The taxonomy of these non-amyloid-spored species will be discussed in a subsequent paper.Only the amyloid-spored species of Aleurodiscus are accounted for in the present paper. The North American and neotropical species are described, discussed, and wherever necessary illustrated. Considerable emphasis has been placed on nomenclature and synonymy. Distribution and host relationships are mentioned and those specimens examined are cited. Five previously described species are recorded for the North American mycoflora for the first time. These include Aleurodiscus aurantius (Pers. per Fr.) J. Schroet., A. disciformis (DC. per Fr.) Pat., A. fennicus Laurila, A. lapponicus Litsch., and A. tsugae Yasuda. Five species are described as new to science: Aleurodiscus abietis Jacks, et Lemke, sp. nov.; A. laurentianus Jacks, et Lemke, sp. nov. A. macrocystidiatus Lemke, sp. nov. A. piceinus Lyon et Lemke, sp. nov.; and A. spiniger Rogers et Lemke, sp. nov. The combination Aleurodiscus lividocoeruleus (Karst.) Lemke, comb. nov. is provided. A new genus, Aleurocystidiellum Lemke, gen. nov. (MONOTYPE: A. subcruentatum (Berk. et Curt.) Lemke, gen. & comb. nov.), is proposed to accommodate an amyloid-spored species not considered to be cogeneric with the other amyloid-spored Aleurodisci. Aleurodiscus stereoides Yasuda is recognized as a facultative synonym of Aleurocystidiellum subcruentatum (Berk. et Curt.) Lemke.The amyloid-spored species of Aleurodiscus (sensu stricto) have been compared with certain of the other amyloid-spored hymenomycetes, and a key to the amyloid-spored Aleurodisci and allied genera is provided under the heading Stereaceae. A discussion of microstructure and terminology for the genus is given to facilitate the use of the key.