Cladosterigma: an enigmatic fungus, previously considered a basidiomycete, now revealed as an ascomycete member of the Gomphillaceae

Phylogenetic revision of the lichenized family Gomphillaceae (Ascomycota: Graphidales) suggests post-K-Pg boundary diversification and phylogenetic signal in asexual reproductive structures

We present the first broad molecular-phylogenetic revision of the lichenized family Gomphillaceae, based on 408 newly generated sequences of the mitochondrial SSU rDNA and nuclear LSU rDNA, representing 342 OTUs. The phylogenetic analysis of 20 out of the 28 currently accepted genera resulted in 48 clades. Twelve genera were resolved as monophyletic: Actinoplaca, Arthotheliopsis, Bullatina, Caleniopsis, Corticifraga, Gomphillus, Gyalectidium, Gyalidea, Jamesiella, Rolueckia, Rubrotricha, and Taitaia. Two genera resulted paraphyletic, namely Aulaxina (including Caleniopsis) and Asterothyrium (including Linhartia). Six genera were in part highly polyphyletic: Aderkomyces, Calenia, Echinoplaca, Gyalideopsis, Psorotheciopsis, and Tricharia. While ascoma morphology and anatomy has traditionally been considered as main character complex to distinguish genera, our study supported the notion that the characteristic asexual anamorph of Gomphillaceae, the so-called hyphophores, are diagnostic for most of the newly recognized clades. As a result, we recognize 26 new genus-level clades, three of which have names available (Microxyphiomyces, Psathyromyces, Spinomyces) and 23 that will require formal description as new genera. We also tested monophyly for 53 species-level names for which two or more specimens were sequenced: 27 were supported as monophyletic and representing a single species, 13 as monophyletic but with an internal topology suggesting cryptic speciation, four as paraphyletic, and nine as polyphyletic. These data suggest that species richness in the family is higher than indicated by the number of accepted names (currently 425); they also confirm that recently refined species concepts reflect species richness better than the broad concepts applied in Santesson's monograph. A divergence time analysis revealed that foliicolous Gomphillaceae diversified after the K-Pg-boundary and largely during the Miocene, a notion supported by limited data available for other common foliicolous lineages such as Chroodiscus (Graphidaceae), Pilocarpaceae, and Porinaceae. This contradicts recent studies suggesting that only macrofoliose Lecanoromycetes exhibit increased diversification rates in the Cenozoic.