A taxonomic revision of Aureobasidium (Saccotheciaceae, Dothideales) with new species, new names, and typifications

Abstract

Aureobasidium comprises dimorphic yeast-like fungi that usually produce melanised cells at maturity. Species are globally distributed and ubiquitous, colonizing a variety of habitats. At present, ca 40 species are accepted, with the type, A. pullulans, representing a complex of unresolved cryptic species. In this study, we isolated 128 Aureobasidium from multiple temperate and tropical regions. We performed multigene analyses using eight loci (ITS, 28S, EF1a, ELO2, RPB2, BTUB, mtLSU and mtSSU) on new isolates and including sequences from type material for all available Aureobasidium species. Data on growth, physiological profiles, micro‘ and macromorphological attributes were also collected and analysed. Several DNA-based species delimitation methods were evaluated for their ability to delimit species. We found that assimilation of D-quinic acid, L-sorbose, D-mannitol, gluconolactone, erythritol, L-arabinose, and sodium succinate dibasic hexahydrate were important in delineating species of Aureobasidium and note that production of pigmentation in culture often takes longer than the 14 d standard for carbon assimilations. Genealogical concordance phylogenetic species recognition criteria (GCPSR) provided the most consistent results for species delimitation. We describe nine new species of Aureobasidium (A. albui, A. cavalettoi, A. diazvalderramae, A. ellingtonae, A. essambei, A. peruvianum, A. rubi, A. toomeae, and A. vanuatuense), make new combinations for A. aubasidani (= A. pullulans var. aubasidani), A. fermentans (= Pullularia fermentans), and A. mahoniae (= Selenophoma mahoniae), validate and provide descriptions for A. musti and A. uvarum, and provide lecto‘ and epitypes for Dematium pullulans, the basionym of A. pullulans. Finally, we resolved the phylogeny for Aureobasidium, reduce Kabatiella (based on K. microsticta) to synonymy, and provide an updated list of species to facilitate future studies.