Ustilaginomycetes on Selaginella

Abstract

The lycophytes represent the most primitive host group for Ustilaginomycetes. Morphology and ultrastructure of the two known smut species on Selaginella, Melanotaenium oreophilum and M. selaginellae, as well as teliospore germination and the 5’ end of the nuclear large subunit rRNA gene of the first species were studied and compared. The results of molecular analyses suggest that these two smut fungi belong either to the Doassansiales or George-fischeriales. The presence of complex interaction apparatus including cytoplasmic compartments favors the placement in the Doassansiales. M. oreophilum and M. selaginellae share the type of septal pore apparatus and host-parasite interaction with the Doassansiales, but not with the Georgefischeriales. They differ from the other members of the Doassansiales in the pigmentation of the teliospores and, at least in M. oreophilum, in the basidial type. To accomodate these two species in the Doassansiales, a new genus, Melaniella, and a new family, Melaniellaceae, are proposed. Descriptions and illustrations are given for Melaniella oreophila and M. selaginellae.