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In 2019, during May to September a unique lichen occurring on soil was collected from four different localities in Deosai National Park, Gilgit-Baltistan, Pakistan. Phylogenetic analysis of the nrDNA ITS and LSU regions revealed that it clustered within the genus Placidium. Further morpho-anatomical and chemical analyses proved its novelty, and it is here described as a new species under the name P. deosaiense. The distinguishing characters of this novel taxon are brown to blackish 2–7 mm wide squamules, undulating in the center, epruinose at margins, epinecral layer up to 70 µm, cylindrical asci with ellipsoid to narrowly ellipsoid ascospores and clavate to bacilliform pycnidiospores.

Premise of the study: Verrucariaceae is a fascinating lineage of lichenized fungi for which generic and species delimitation is problematic due to the scarcity of discriminating morphological characters. Members of this family inhabit rocks, but they further colonize soils, barks, mosses, and other lichens. Our aim is to contribute to the DNA-based inference of the Verrucariaceae tree of life and to investigate characters that could be useful for proposing a more natural classification. We focused on catapyrenioid genera, which are often part of biological soil crusts, a cryptogam-dominated ecosystem contributing to soil formation and stabilization in arid environments. Understanding their evolution and taxonomy is essential to assess their roles in these fragile and important ecosystems. Methods: A multigene phylogeny of Verrucariaceae including catapyrenioid genera is presented. We further examined the phylogenetic relationships among members of Heteroplacidium and Placidium. The evolution of selected characters was inferred using the latter phylogeny. Key results: Anthracocarpon and Involucropyrenium were closely related to Endocarpon. Placidium comprised two monophyletic clades sister to Heteroplacidium. Inferred ancestral states of diagnostic characters revealed that the type of medulla and the pycnidia location were homoplasious within the Placidium clade. In contrast, the presence of rhizines was a synapomorphy for Clavascidium. Conclusions: Our results provide new information on the usefulness of characters for delineating groups in Verrucariaceae. Taxonomic changes are proposed to reflect more natural groupings: Heteroplacidium podolepis is transferred to Placidium, and Clavascidium is recognized as a different genus. Eight new combinations are proposed for Clavascidium.

The current classification of what used to be called Catapyrenium comprises eight genera belonging to distinct lineages in the Verrucariaceae. Previous phylogenetic studies have shown that the redefined genus Catapyrenium (Catapyrenium s. str.) is monophyletic and sister of Placidiopsis within the Staurothele group, but this relationship was based on only two species from each genus. We conducted a phylogenetic study of Catapyrenium and Placidiopsis as currently delimited to evaluate the monophyly of each genus and infer infrageneric relationships. An initial family level phylogenetic analysis based on the nuLSU locus and implementing a backbone constraint tree (with both weighted maximum parsimony and bootstrap maximum likelihood approaches) was performed to infer phylogenetic placements of Catapyrenium and Placidiopsis taxa not included in previous molecular systematic studies. The results of this analysis were used to define the ingroup for a second phylogenetic analysis based on nuITS and nuLSU and centered on Catapyrenium s. str. and Placidiopsis. Placidiopsis was found to be monophyletic, whereas Catapyrenium s. str. was not. Catapyrenium dactylinum was found to be closely related to Placopyrenium caeruleopulvinum and Placopyrenium stanfordii, all of which were closely related to Placocarpus schaereri and Verrucula. In addition we found genus Placopyrenium to be polyphyletic. The resulting trees confirmed that Catapyrenium s. str. (excluding C. dactylinum) and Placidiopsis constitute two sister monophyletic entities. The data do not support Placidiopsis cinerascens and P. tenella as two distinct species because no characters can be used to distinguish them. Thus P. tenella is here reduced to synonymy with P. cinerascens.

A taxonomic treatment of the genera included in Catapyrenium s. lat. in the Iberian Peninsula and the Balearic Islands is provided, based on study of c. 2000 specimens from both herbaria and fresh material collected by the authors from 2005 to 2009 in numerous localities. A total of 33 species belonging to six of the eight genera included in Catapyrenium s. lat. are present in the region, which correspond to c. 80% of species from Europe. The genera are Anthracocarpon Breuss, Catapyrenium Flot. (Catapyrenium s. str.), Heteroplacidium Breuss, Involucropyrenium Breuss, Neocatapyrenium H. Harada and Placidium A. Massal. The genus Neocatapyrenium is reported for the first time from this region. Clavascidium liratum, the only representative of the genus Clavascidium in the region, has been reduced to synonymy with Anthracocarpon virescens. Heteroplacidium acervatum, H. congestum and Neocatapyrenium cladonioideum are new to Europe. Involucropyrenium pusillum, only previously known from Austria, I. waltheri, an arctic-alpine species, and Neocatapyrenium latzelii, known from Croatia and Greece, are cited for the first time in the Iberian Peninsula. Placidium subrufescens and P. tenellum, two mainly Mediterranean species, are also new records from the Iberian Peninsula. Placidium boccanum is here for the first time cited in Spain, and Anthracocarpon virescens, Heteroplacidium contumescens, Placidium imbecillum and P. michelii are new to Portugal. Most of the remaining species showed a considerable expansion of their known ranges. Placidium pyrenaicum is reduced to synonymy with P. velebiticum. Keys to genera and species occurring in the Iberian Peninsula and the Balearic Islands are presented.

Catapyrenium pyrenaicum is described as new from northern Spain and adjacent France, and the new combination Catapyrenium velebiticum is made. The new species differs from C. velebiticum mainly in its laminal pycnidia. Remarks on taxonomy, ecology, and distribution of the species are given.

Range extensions are cited for Catapyrenium acarosporoides and C. compactum. Catapyrenium daedaleum and C. schaereri are added to the treatment. Two species, Catapyrenium globosum Thoms. and C. radiatum Thoms. are described as new. A revised key to the species in North America is provided.

13 species of the lichen genus Catapyrenium are reported from South America. Five species (C. analogicum, C. andicolum, C. exaratum, C. lachneoides, and C. podolepis) are described as new. A key to the species known from South America is presented. Remarks on taxonomy, ecology and distribution of the species are given.

Seven species of Catapyrenium and one of Placidiopsis are reported from Greenland. Five taxa, viz. Catapyrenium michelii, C. norvegicum, C. squamulosum, C. waltheri and Placidiopsis pseudocinerea are new to the area. Taxonomy, distribution and ecology are briefly discussed. A key to species and distribution maps are presented. Catapyrenium norvegicum is described as new.

Verrucaria schaereri (Fr.) Nyl. is accorded generic status as Placocarpus Trev. emend. O. Breuss. The main differences between the two genera concern the thallus anatomy and the spores which are halonate in Placocarpus. The following new combinations are proposed: Placocarpus schaereri (Fr.) O. Breuss and Placidiopsis cinerascens (Nyl.) O. Breuss.