The fungal genus Collemopsidium comprises species that develop so-called borderline lichen symbioses with algae or cyanobacteria. Together with morphologically similar pyrenocarpous fungi it has been assigned to the family Xanthopyreniaceae. The adscription of this family to higher taxonomic ranks remain uncertain. Using sequence data of five nuclear genomic regions (nuLSU, nuSSU, tef1-α, rpb1 and rpb2) and one mitochondrial locus (mtSSU) we found that the studied representatives of this family are placed in the Dothideomyceta, yet relationships with the classes Dothideomycetes and Arthoniomycetes remain uncertain. We describe the new order Collemopsidiales to accommodate the genus Collemopsidium (paraphyletic as currently understood) and the lichenicolous genus Zwackhiomyces. Using five fungal fossils as calibrations points, we infer an age of c. 230 Mya for the crown of Collemopsidiales. Based on two molecular markers, we also provide insight into the global diversity of marine species of the genus Collemopsidium. According to the species delimitation algorithm GMYC, c. 26 putative species exist, far more than the six species recognized hitherto. We have confirmed this result by comparing the two alternative species models by means of Bayes factors, using path sampling and stepping-stone sampling algorithms to estimate the marginal likelihood of each model. Finally, our observations suggest rock-boring ability evolved in parallel in the different lineages within this group of fungi.

Compared to other organisms, such as vascular plants or mosses, lichen‐forming fungi have a high number of species occurring in both northern and southern hemispheres but are largely absent from intermediate, tropical latitudes. For instance, ca. 160 Antarctic species also occur in polar areas or mountainous temperate regions of the northern hemisphere. Early interpretations of this particular distribution pattern were made in terms of vicariance or long‐distance dispersal. However, it was not until the emergence of phylogenetics and the possibility of dating past diversification and colonization events that these initial hypotheses started to be evaluated. The premise of a relatively recent colonization of the southern hemisphere by boreal lichens through long‐distance dispersal has gained support in recent studies based on either the comparison of genetic affinities (i.e., tree topology) or more robust, statistical migratory models. Still, the scarcity of such studies and a concern that taxonomic concepts for bipolar lichens are often too broad preclude the generation of sound explanations on the mechanisms and origin of such fascinating disjunct distributions.This review provides an up‐to‐date overview of bipolar distributions in lichen‐forming fungi and their photobionts. Evidence provided by recent, molecular‐based studies as well as data on the type of lichen reproduction, dispersal ability, photobiont identity and availability, and habitat preferences are brought together to discuss how and when these distributions originated and their genetic footprints. Ideas for future prospects and research are also discussed.

Since its resurrection, the resinicolous discomycete genus Sarea has been accepted as containing two species, one with black apothecia and pycnidia, and one with orange. We investigate this hypothesis using three ribosomal (nuITS, nuLSU, mtSSU) regions from and morphological examination of 70 specimens collected primarily in Europe and North America. The results of our analyses support separation of the traditional Sarea difformis s.lat. and Sarea resinae s.lat. into two distinct genera, Sarea and Zythia. Sarea as circumscribed is shown to conservatively comprise three phylospecies, with one corresponding to Sarea difformis s.str. and two, morphologically indistinguishable, corresponding to the newly combined Sarea coeloplata. Zythia is provisionally maintained as monotypic, containing only a genetically and morphologically variable Z. resinae. The new genus Atrozythia is erected for the new species A. klamathica. Arthrographis lignicola is placed in this genus on molecular grounds, expanding the concept of Sareomycetes by inclusion of a previously unknown type of asexual morph. Dating analyses using additional marker regions indicate the emergence of the Sareomycetes was roughly concurrent with the diversification of the genus Pinus, suggesting that this group of fungi emerged to exploit the newly-available resinous ecological niche supplied by Pinus or another, extinct group of conifers. Our phylogeographic studies also permitted us to study the introductions of these fungi to areas where they are not native, including Antarctica, Cape Verde, and New Zealand and are consistent with historical hypotheses of introduction.