Tackling fungal diversity in lichen symbioses: molecular and morphological data recognize new lineages in Chaetothyriales (Eurotiomycetes, Ascomycota)

Lichens have been reappraised as self-sustaining and long-living ecosystems in which a multiplicity of microorganisms are housed, in addition to the main symbiotic partners. Lichen-associated microfungi can frequently occur cryptically, and their species diversity has recently been more fully elucidated by DNA metabarcoding studies and culture isolations. These lichen-associated fungi represent a wide array of major lineages in ascomycetes and basidiomycetes, including both filamentous and yeast species. Thanks to culture isolations, the morphology of a subset of the lichen-associated microfungal diversity has been studied. Metabarcoding analyses have shown high diversity of ascomycetous lichen-associated fungi in the two cosmopolitan rock-inhabiting lichens – Rhizoplaca melanophthalma and Tephromela atra – and many of these taxa were successfully isolated in culture. Based on DNA sequence data and morphological analyses, two new lineages within Chaetothyriales are here recognized. Both occur in lichens from dry habitats and are described here as the new species Cladophialophora endolichena Cometto, de Hoog, Muggia and Paracladophialophora lichenicola Cometto, de Hoog, Muggia. Other strains are placed in Pleostigmataceae, Trichomeriaceae, Pleosporales, Mycosphaerellales, Coniochaetales and Hypocreales, further filling gaps of knowledge of the high fungal diversity residing in lichen thalli.