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.

Miocene Ethiopian amber: A new source of fossil cryptogams

“…The fossil from Ethiopian amber can confidently be identified as a foliose lichen, which renders it the very first fossil lichen known from Africa. Ethiopian amber is consequently the fourth amber deposit containing lichen in the world, along with the Dominican, Baltic, and Bitterfeld ambers (Kaasalainen et al, 2015, 2017a, 2017b, 2019, 2020; Rikkinen et al, 2018). This underlines the importance of amber as a rich palaeontological material and especially when looking for well‐preserved, very small cryptogamic specimens.…”

Fossil Usnea and similar fruticose lichens from Palaeogene amber

“…The Palaeogene fossils of Anzia , Calicium , Chaenotheca and Chaenothecopsis , and the Miocene Phyllopsora (Rikkinen & Poinar 2002, 2008; Rikkinen et al . 2018) in particular have been used for this purpose (e.g. Beimforde et al .…”

“…( Coniocybaceae ) and Ochrolechia A. Massal. ( Ochrolechiaceae ), together with the obligately lichenicolous fungus Lichenostigma Hafellner of the Phaeococcomycetaceae ) (Rikkinen & Poinar 2002; Rikkinen 2003; Rikkinen et al 2018; Kaasalainen et al 2019; Kettunen et al 2019). In addition, specimens of Phyllopsora Müll.…”

“…Also, several fossils of the non-lichenized but now often lichenicolous genus Chaenothecopsis Vain. ( Mycocaliciaceae ) have been found from both Baltic and Bitterfeld amber (Rikkinen & Poinar 2000; Tuovila et al 2013; Rikkinen et al 2018). Finally, many fossil macrolichens with, for example, alectorioid and parmelioid thallus morphologies and lichen-associated hyphomycetes are known from European and Dominican ambers, but most of these cannot be assigned to any fungal genus (Poinar et al 2000; Kaasalainen et al 2015, 2017 a ; Kettunen et al 2016, 2017).…”

Chaenothecopsis (Mycocaliciales, Ascomycota) from exudates of endemic New Zealand Podocarpaceae

“…Several fossils in Paleogene amber demonstrate that the ascoma morphology and resinicolous ecology of conifer-associated taxa have remained unchanged for tens of millions of years ( Rikkinen and Poinar 2000 ; Tuovila et al 2013 ; Rikkinen et al 2018 ; Rikkinen and Schmidt 2018 ), but the evolutionary origin of the resinicolous ecology within the Mycocaliciales is still unclear. Molecular phylogenetic analyses indicate that the resinicolous ecology on conifer resin predates fungi occupying angiosperm exudate.…”