Ustilaginomycetes on Selaginella

The lycophytes represent the most primitive host group for Ustilaginomycete s. Morphology and ultrastructure of the two known smut species on Selaginel la, Melanotaenium oreophilum and M. selaginellae, as well as teliospore ger mination and the 5' end of the nuclear large subunit rRNA gene of the first species were studied and compared. The results of molecular analyses sugge st that these two smut fungi belong either to the Doassansiales or George-f ischeriales. The presence of complex interaction apparatus including cytopl asmic compartments favors the placement in the Doassansiales. M. oreophilum and M. selaginellae share the type of septal pore apparatus and host-paras ite interaction with the Doassansiales, but not with the Georgefischeriales . They differ from the other members of the Doassansiales in the pigmentati on of the teliospores and, at least in M. oreophilum, in the basidial type. To accomodate these two species in the Doassansiales, a new genus, Melanie lla, and a new family, Melaniellaceae, are proposed. Descriptions and illus trations are given for Melaniella oreophila and M. selaginellae.