Reference-Based Restriction-Site-Associated DNA Sequencing Data Are Useful for Species Delineation in a Recently Diverged Asexually Reproducing Species Complex (Parmeliaceae, Ascomycota).

Cryptic species are common in lichen-forming fungi and have been reported from different genera in the most speciose family, Parmeliaceae. Herein, we address species delimitation in a group of mainly asexually reproducing Parmelina species. The morphologically distinct P. pastillifera was previously found nested within a morphologically circumscribed P. tiliacea based on several loci. However, these studies demonstrated a relatively high genetic diversity within P. tiliacea sensu lato. Here, we revisit the species delimitation in the group by analyzing single-nucleotide polymorphisms (SNPs) through genome-wide assessment using Restriction-Site-Associated sequencing and population genomic methods. Our data support previous studies and provide further insight into the phylogenetic relationships of the four clades found within the complex. Based on the evidence suggesting a lack of gene flow among the clades, we recognize the four clades as distinct species, P. pastillifera and P. tiliacea sensu stricto, and two new species, P. clandestina sp. nov. and P. mediterranea sp. nov.

Reference-Based RADseq Unravels the Evolutionary History of Polar Species in 'the Crux Lichenologorum' Genus Usnea (Parmeliaceae, Ascomycota).

Nearly 90% of fungal diversity, one of the most speciose branches in the tree of life, remains undescribed. Lichenized fungi as symbiotic associations are still a challenge for species delimitation, and current species diversity is vastly underestimated. The ongoing democratization of Next-Generation Sequencing is turning the tables. Particularly, reference-based RADseq allows for metagenomic filtering of the symbiont sequence and yields robust phylogenomic trees of closely related species. We implemented reference-based RADseq to disentangle the evolution of neuropogonoid lichens, which inhabit harsh environments and belong to Usnea (Parmeliaceae, Ascomycota), one of the most taxonomically intriguing genera within lichenized fungi. Full taxon coverage of neuropogonoid lichens was sampled for the first time, coupled with phenotype characterizations. More than 20,000 loci of 126 specimens were analyzed through concatenated and coalescent-based methods, including time calibrations. Our analysis addressed the major taxonomic discussions over recent decades. Subsequently, two species are newly described, namely U. aymondiana and U. fibriloides, and three species names are resurrected. The late Miocene and Pliocene-Pleistocene boundary is inferred as the timeframe for neuropogonoid lichen diversification. Ultimately, this study helped fill the gap of fungal diversity by setting a solid backbone phylogeny which raises new questions about which factors may trigger complex evolutionary scenarios.

Phylogenetic study and taxonomic revision of the Xanthoparmeliamexicana group, including the description of a new species (Parmeliaceae, Ascomycota).

Xanthoparmelia (Parmeliaceae, Ascomycota) is the most species-rich genus of lichen-forming fungi. Species boundaries are based on morphological and chemical features, varying reproductive strategies and, more recently, molecular sequence data. The isidiate Xanthoparmeliamexicana group is common in arid regions of North and Central America and includes a range of morphological variation and variable secondary metabolites - salazinic or stictic acids mainly. In order to better understand the evolutionary history of this group and potential taxonomic implications, a molecular phylogeny representing 58 ingroup samples was reconstructed using four loci, including ITS, mtSSU, nuLSU rDNA and MCM7. Results indicate the existence of multiple, distinct lineages phenotypically agreeing with X.mexicana. One of these isidiate, salazinic acid-containing lineages is described here as a new species, X.pedregalensis sp. nov., including populations from xerophytic scrub vegetation in Pedregal de San Angel, Mexico City. X.mexicana s. str. is less isidiate than X.pedregalensis and has salazinic and consalazinic acid, occasionally with norstictic acid; whereas X.pedregalensis contains salazinic and norstictic acids and an unknown substance. Samples from the Old World, morphologically agreeing with X.mexicana, are only distantly related to X.mexicana s. str. Our results indicate that X.mexicana is likely less common than previously assumed and ongoing taxonomic revisions are required for isidiate Xanthoparmelia species.