Phylogenetic analyses of Aleurodiscus s.l. and allied genera

Abstract

The limits and possible subdivision of Aleurodiscus s.l. into Acanthobasidium, Acanthofungus, Acanthophysellum, Aleurobotrys, Aleurocystidiellum, Aleurodiscus s.s., and Gloeosoma were evaluated. Molecular characters were obtained from an approximately 980 base pair fragment at the 5’ end of the nuclear large subunit ribosomal DNA, in 33 strains representing 23 species of Aleurodiscus s.l., Stereum, Xylobolus, and Megalocystidium leucoxanthum. Published sequences of 20 additional species of the russuloid clade were also included. Phylogenetic analyses suggest that Aleurodiscus s.l., Megalocystidium leucoxanthum, Stereum and Xylobolus form a monophyletic group, which may be classified as the family Stereaceae. Corticium roseum, which is the type species of the Corticiaceae, is not in this group, thus Stereaceae is not synonymous with Corticiaceae. Aleurocystidiellum is supported as a monophyletic group. Acanthobasidium, which is characterized by pleurobasidia, is also monophyletic. Aleurodiscus s.s. is supported as monophyletic, but Gloeosoma is not, and the two are not congeneric. The importance of amyloid acanthophyses for recognizing Aleurobotrys is suspect, and its generic status should be further studied. Most of the smooth-spored species form a monophyletic group. Phylogenetic analyses suggest that there has been homoplasy in most of the characters that have been used to subdivide Aleurodiscus s.l., including spore ornamentation, hymenial color, hyphal septation, clamp connections, acanthophyses, and phenoloxidase reactions.

Key Words:

• Basidiomycota
• corticioid fungi
• molecular systematics
• russuloid clade