Diversity and novel lineages of black yeasts in Chaetothyriales from freshwater sediments in Spain

Black yeasts comprise a group of ascomycetes of the order Chaetothyriales with highly variable morphology, a great diversity of ecological niches and life cycles. Despite the ubiquity of these fungi, their diversity in freshwater sediments is still poorly understood. During a survey of culturable ascomycetes from river and stream sediments in various Spanish sites, we isolated a set of black yeasts by using potato dextrose agar supplemented with cycloheximide. A preliminary morphological study and sequence analyses of the internal transcribed spacer region (ITS) and the large subunit (LSU) of the nuclear rDNA revealed that most of the isolates belonged to the family Herpotrichiellaceae, but only 63.83% of them could be identified at the species level (i.e., Capronia pulcherrima, Cladophialophora emmonsii, Exophiala equina, Exophiala pisciphila, Exophiala radicis, and Phialophora americana). 36.17% of the specimens could not be assigned to any known species of chaetohyrialean fungi. Combining morphological and ecological data with a multi-locus phylogenetic analysis based on the ITS, LSU, β-tubulin and translation elongation factor 1–α gene markers, we propose the new genus Aciculomyces in the Herpotrichiellaceae to accommodate the novel species Aciculomyces restrictus. Other novel species in this family include Cladophialophora denticulata, Cladophialophora heterospora, Cladophialophora irregularis, Exophiala candelabrata, Exophiala dehoogii, Exophiala ramosa, Exophiala verticillata and Phialophora submersa. The new species Cyphellophora spiralis and the new combination Anthopsis clematitidis are proposed in the family Cyphellophoraceae