Phylogenetic relationships of Cryptococcus neoformans and some related basidiomycetous yeasts determined from partial large subunit rRNA sequences.

The genus Cryptococcus was found to be heterogeneous on the basis of partial rRNA sequences. The human-pathogenic species C. neoformans, comprising 4 serotypes and having Filobasidiella neoformans and F. bacillispora as teleomorphs, was found at a relatively large distance from Filobasidium. Serotypes B and C had identical sequences, while in A and D they were different, with D closer to B and C than to A. Filobasidiella depauperata, which lacks a yeast-like anamorph, clustered with F. neoformans. The genus Filobasidium was clearly separated from Filobasidiella and clustered with C. albidus, C. kuetzingii, C. gastricus, C. lupi, C. vishniaciae, C. bhutanensis, C. aerius, C. terreus and C. ater. The latter may represent the anamorph of Filobasidium elegans. The orange to red species of Cryptococcus, as well as C. aquaticus and C. yarrowii, were found completely unrelated with these taxa, C. macerans being affiliated to Cystofilobasidium capitatum. The genus Trichosporon was found relatively homogeneous; it includes C. humicola, C. curvatus and the filamentous species Hyalodendron lignicola. Cryptococcus flavus and C. dimennae probably belong to the Tremellales, though distances between these species are large. The positions of C. laurentii and C. luteolus remains to be determined.