Two New Genera of Leaf-Parasitic Fungi (Basidiomycetidae: Brachybasidiaceae)

SUMMARY

Proliferobasidium and Ceraceosorus (Brachybasidiaceae, Brachybasi-diales, Basidiomycetes) are described as new genera. Both cause leaf-spot diseases of vascular plants and are characterized by persistent thick-walled probasidia and bisterigmate metabasidia. They differ from Dicellomyces, the most closely related genus, in having indeterminate rather than determinate hymenial thickening and in lacking a fruiting body with extensive sterile tissue. Proliferobasidium is based on P. heliconiae, described as a new species on Heliconia bihai. It has intercellular hyphae and exhibits repeated percurrent proliferation of new basidia from within persistent probasidial walls. Ceraceosorus, with the type species Dicellomyces bombacis on Bombax ceiba, has intracellular hyphae and lacks percurrent proliferation of basidia. Ceraceosorus bombacis is presented as a new combination. Since they have features in common with Uredinales, Dacrymycetales, and corticioid Homobasidiomycetes, Ceraceosorus and Proliferobasidium may prove to be of considerable evolutionary interest.