A new species of a dimorphic simple-pored auricularioid heterobasidiomycete, Occultifur externus, is described. This fungus was initially isolated in the unicellular stage and identified, on the basis of standard yeast identification tests, as the anamorphic pink yeast Rhonotorula minuta. This yeast was able to complete its life cycle on solid laboratory media. Two yeast cells conjugated, forming mycelium with clamp connections. The same generative hyphae produced clusters of four-celled basidia and characteristic swollen conidiogenic cells that released dikaryotic conidia. Haustorialike structures were formed. Nuclear DNA-DNA hybridization experiments revealed that O. externus is not the teleomorphic stage of R. minuta and molecular sequence data from the large subunit of the rDNA supported the affiliation of O. externus to the Naohidea-Sakaguchia clade of the Urediniomycetes. Ultrastructural studies revealed the presence of simple septal pores. Cylindrical reticulate bodies were frequently found occluding them. These unique bodies could also be detected in O. internus, which supports the placement of both taxa in the same genus.