Lichinodium is a new lichenized lineage in the Leotiomycetes

Here, we show that Lichinodium (Lichinaceae, Lichinomycetes, Ascomycota) constitutes a formerly unrecognized lineage within the Leotiomycetes, thus being the first lichenized lineage recognized in the superclass Sordariomyceta (Leotiomycetes, Laboulbeniomycetes and Sordariomycetes). To infer the position of Lichinodium, we constructed two multilocus phylogenies based on six and five gene regions (nuLSU rDNA, nuSSU rDNA, mtSSU rDNA, RPB1, RPB2 and MCM7) including main Pezizomycotina groups in the first analysis and focusing secondly on a comprehensive selection of Sordariomyceta. The results show that Lichinodium is sister to Leotiaceae. We discuss the morphological and ecological similarities between Lichinodium and other Leotiomycetes, and describe the new order Lichinodiales and family Lichinodiaceae. The sister relationship between Sordariomycetes and Laboulbeniomycetes is here supported as it is the relationship between this clade and the Leotiomycetes. The results also support the polyphyly of Helotiales, the recognition of the Leotiales in a strict sense or the inclusion of the Triblidiales in Leotiomycetes. The photobionts of Lichinodium were sequenced for two genetic markers (rbcLX and 16S rDNA) and identified as Rhizonema, a recently described genus of filamentous cyanobacteria belonging to Nostocaceae. TEM studies revealed that the mycobiont-cyanobiont interface in Lichinodium does not produce haustoria, thus differing from a typical Lichinomycete (e.g. Ephebe).