Auriculibuller fuscus gen. nov., sp. nov. and Bullera japonica sp. nov., novel taxa in the Tremellales

Seven phylloplane yeast strains that were collected in the Arrábida Natural Park, Portugal, and identified preliminarily as Bullera alba, the anamorphic stage of Bulleromyces albus, were investigated. In contrast to Bulleromyces albus, these isolates produced a brownish pigment when grown on potato dextrose agar. The pigment caused darkening of the cultures and diffused into the culture medium. Mating studies revealed that the Arrábida isolates did not react with the different mating types of Bulleromyces albus, but were sexually compatible with them and produced mycelium with clamp connections, haustoria and transversally septate basidia that ejected the basidiospores. Various taxonomic criteria that were evaluated during the present study and comparison with other sexual taxa of the Tremellales indicated that this teleomorph should be classified in a novel genus. Therefore, Auriculibuller fuscus gen. nov., sp. nov. (type strain, PYCC 5690^T = CBS 9648^T) is proposed. In addition, during the course of this investigation, a member of a novel Bullera species, Bullera japonica sp. nov. (type strain, PYCC 4534^T = CBS 2013^T), was found among collection isolates that were identified formerly as Bullera alba. In molecular phylogenetic analysis of the D1/D2 domains of the 26S rDNA and the internal transcribed spacer region, the two taxa were found to be closely related, but distinct at the species level.