Abstract
<jats:p> Fungi represent the largest group of plant pathogens, causing significant economic losses in agriculture and forestry worldwide. Species of the genus <jats:italic>Exobasidium</jats:italic> ( <jats:italic>Exobasidiales</jats:italic> , <jats:italic>Basidiomycota</jats:italic> ) are considered pathogens of plants from the order <jats:italic>Ericales</jats:italic> . While <jats:italic>Exobasidium</jats:italic> species notably impact tea and fruit production, their complete life cycles remain poorly understood, which hampers their management. These species are characterized by a dikaryotic parasitic stage tightly associated with living host tissues and a haploid, yeast-like saprotrophic stage. The prevalence, ecological significance, and potential contribution of this saprotrophic stage to the persistence of <jats:italic>Exobasidium</jats:italic> outside living host plants remain understudied. In this study, we confirmed the presence of several <jats:italic>Exobasidium</jats:italic> species in the leaf phyllosphere of five broad-leaved tree species in Central Europe using both cultivation and environmental DNA ITS2-based approaches. Additionally, we describe a new species without a known parasitic phase, <jats:italic>E. phylloplanum</jats:italic> <jats:bold>sp. nov</jats:bold> ., along with its physiological description and annotated genome. Environmental DNA surveys, using the GlobalFungi database, revealed that <jats:italic>E. phylloplanum</jats:italic> is not only common locally but also the most frequently detected <jats:italic>Exobasidium</jats:italic> lineage worldwide. This broad ecological amplitude contrasts with the narrow host specificity typical of parasitic congeners, suggesting that <jats:italic>E. phylloplanum</jats:italic> has adapted to a generalist saprotrophic life-history strategy. Our findings demonstrate that <jats:italic>Exobasidium</jats:italic> species can persist saprotrophically on diverse hosts, suggesting a broader ecological role and higher diversity than previously recognized. This research elucidates the diverse ecological roles of <jats:italic>Exobasidium</jats:italic> species and suggests that further genomic studies could reveal the genetic factors that underpin the different life strategies within this genus. </jats:p>