Calicioid lichens and fungi in amber – Tracing extant lineages back to the Paleogene

Abstract Calicioid lichens and fungi are a polyphyletic grouping of tiny ascomycetes that accumulate a persistent spore mass (mazaedium) on top of their usually well-stalked ascomata (‘mazaediate fungi’). In addition to extant forms, six fossils of the group were previously known from European Paleogene amber. Here we report nine new fossils and analyze the preserved features of all fossils to assess their applicability for dating molecular phylogenies. Many fossils are extremely well preserved, allowing detailed comparisons with modern taxa. SEM investigation reveals that even fine details of ascospore wall ultrastructure correspond to those seen in extant specimens. All fossils can confidently be assigned to modern genera: three to Calicium (Caliciaceae, Lecanoromycetes), five to Chaenotheca (Coniocybaceae, Coniocybomycetes), six to Chaenothecopsis (Mycocaliciaceae, Eurotiales), and one to Phaeocalicium (Mycocaliciaceae, Eurotiales). Several Calicium and Chaenotheca fossils are assignable to specific lineages within their genera, while the Chaenothecopsis fossils demonstrate the extent of intraspecific variation within one such lineage. Some features in the morphology of Chaenotheca succina nov. sp. seem to be ancestral as they have not been reported from modern species of the genus.