Sporidiobolus longiusculus sp nov and Sporobolomyces patagonicus sp nov., novel yeasts of the Sporidiobolales isolated from aquatic environments in Patagonia, Argentina

During a survey of carotenogenic yeasts carried out in north-western Patagonia (Argentina), several ballistoconidia-producing strains belonging to the order Sporichobolales were isolated from aquatic environments. Five strains were found to represent two novel species, for which the names Sporidiobolus longiusculus and Sporobolomyces patagonicus are proposed, with CBS 9654(T) (= PYCC 5818(T) = CRUB 1044(T)) and CBS 9657(T) (= PYCC 5817(T) = CRUB 1038(T)) as the type strains, respectively. The elongated basidia, which are five to six times longer that those of the remaining species of the genus Sporidiobolus, are a particular micromorphological feature of Sporidiobolus longiusculus. On the basis of the sequences of the D1/D2 domains of the 26S rRNA gene, the species most closely related to Sporidiobolus longiusculus is Sporobolomyces bannaensis, whereas Sporobolomyces marcillae is the closest relative of Sporobolomyces patagonicus. Complete internal transcribed spacer sequence analysis confirmed the separate position of Sporidiobolus longiusculus, whereas for Sporobolomyces patagonicus no nucleotide differences were found with respect to Sporidiobolus pararoseus CBS 491 T. Negative mating experiments between strains of Sporobolomyces patagonicus and strains of Sporidiobolus pararoseus together with the low DNA-DNA reassociation values for the type strains of the two species validated the proposal of Sporobolomyces patagonicus as a distinct species. Information on additional Patagonian Sporobolomyces isolates is also included in this report.