Multiple origin of the lichenicolous life habit in Helotiales, based on nuclear ribosomal sequences

The Helotiales are an ecologically and morphologically highly diverse group of ascomycetes that also includes lichen-inhabiting (lichenicolous) species. We generated sequence data of three rDNA regions (nuSSU, nuLSU, 5.8S of ITS) from 28 lichenicolous specimens representing nine genera in order to determine their phylogenetic placement. Based on the most complete dataset of helotialean fungi to date, the analyses were performed using Maximum Likelihood (ML) and Bayesian approaches. Our results suggest that 1) the lichen-inhabiting life-style in Helotiales was subjected to gains or losses at least three times; 2) Thamnogalla, previously tentatively included in Ostropales, is shown to belong to Helotiales; 3) ascomata found intermixed with pycnidia of the asexual Diplolaeviopsis ranula and possessing the same pigments are tentatively considered as the sexual morph of this taxon, and are shown to belong to Helotiales; 4) the lichenicolous species of cf. Diplolaeviopsis, Llimoniella, Rhymbocarpus, Skyttea, Thamnogalla and Unguiculariopsis form a well-supported clade together with non-lichenicolous encoelioid fungi from the genera Ionomidotis, Cordierites and Encoelia; 5) Geltingia associata forms a highly supported clade with the fungicolous asexual fungus Eleutheromyces subulatus, whereas Pezizella epithallina clusters with an aquatic asexual fungus Tetracladium sp.; 6) Phaeopyxis punctum belongs to Ostropomycetidae (Lecanoromycetes), but its deep relationships to other groups remain unresolved based on rDNA sequences.