Cystofilobasidium lacus-mascardii sp. nov., a basidiomycetous yeast species isolated from aquatic environments of the Patagonian Andes, and Cystofilobasidium macerans sp. nov., the sexual stage of Cryptococcus macerans.

Here, we report on two novel sexual basidiomycetous red yeast species of the genus Cystofilobasidium. Cystofilobasidium lacus-mascardii sp. nov. is based on sexually compatible strains isolated from Lake Mascardi, an ultraoligotrophic lake in north-western Patagonia, Argentina. Following the discovery of the first isolate of this species, additional (sexually compatible) strains were isolated using a selective medium containing erythritol as the sole source of carbon. The second novel species corresponds to the sexual state of Cryptococcus macerans. In spite of accounts over the last 20 years of sexually compatible strains of this species, the complete life has never been observed. We provide evidence of a Cystofilobasidium-like basidial stage with teliospores and slender holobasidia, based on the study of self-fertile (homothallic) and self-sterile (heterothallic) isolates of Cryptococcus macerans. A revised molecular phylogeny of the genus Cystofilobasidium is presented and the most salient features of Cystofilobasidium lacus-mascardii sp. nov. (type strain CBS 10642(T) =PYCC 5819(T) =CRUB 1046(T)) and Cystofilobasidium macerans sp. nov. (type strain CBS 10757(T)) are discussed and compared with those of the remaining species in the genus. Information on additional Patagonian isolates belonging to the Cystofilobasidiales is also included in this report.