F. arachnophila differs from other species of the genus in the absence of a cryptococcoid anamorph, in the lack of clamp connections in the hyphae and in its inability to hydrolyze urea, oxidize phenolic compounds and synthesize starch. Its septal ultrastructure is similar to that of F. neoformans and species of Trichosporon, Trichosporonoides, Tremella, Tilletia, Moniliella and Hyalodendron, all of which have a flared (dolipore) septum without the pore caps (parenthesomes) typical of most higher basidiomycetes. This type of septal pore apparatus is typical of the Filobasidiaceae and a number of yeastlike genera of uncertain affinities. The final generic position of F. arachnophila must await determination of whether the spores formed in this species are mitospores or meiospores.