Caspary's fungi from Baltic amber: historic specimens and new evidence

Abstract

Amber is a valuable source of Mesozoic and Cenozoic fossil fungi. The earliest amber‐preserved fungi were described in the nineteenth and early twentieth centuries from Eocene Baltic amber. In 1907, Richard Klebs summarized the legacy of Robert Caspary based on his specimens, research notes and publications. This treatise contains descriptions and illustrations of 13 morphologies of fossil fungi which have not been investigated since. We managed to locate six of Caspary's amber specimens and imaged and re‐investigated the fossil fungi within. We provide amended descriptions of these six specimens, select new specimens from historic and recent collections which are probably conspecific with five fossils that appear to have been lost, and finally also describe and evaluate five newly found fossil fungi from Baltic amber. The fungi belong to the phylum Ascomycota (Subkingdom Dikarya). Only two of Caspary's fungi can be confidently assigned to modern genera, Metacapnodium (Metacapnodiaceae) and Calicium (Caliciaceae). The new combination Calicium succini (Caspary) Rikkinen & A. R. Schmidt is made. The fossils originally placed in Acremonium, Cetraria, Gonatobotrys, Ramularia, Stilbum and Torula cannot be assigned to these genera, and should not be used as minimum age constrains for the respective lineages.

Morphological Convergence in Forest Microfungi Provides a Proxy for Paleogene Forest Structure

“…The first fossil of a calicioid lichen from Baltic amber was described by Robert Caspary in 1886 as Stilbum succini and recently transferred to the genus Calicium in Kettunen et al (2018). The ascospores of this fossil are similar to those of another Calicium specimen recently found from Bitterfeld amber, which also revealed many details in ascospore ultrastructure (Rikkinen et al, 2018).…”

“…Indeed, no fewer than six specimens of resinicolous Chaenothecopsis have been found from Baltic and Bitterfeld ambers (Rikkinen and Poinar, 2000;Tuovila et al, 2013;Rikkinen et al, 2018). Also, three specimens of Calicium, five fossil specimens of Chaenotheca, and one specimen of Phaeocalicium have so far been found (Rikkinen, 2003b;Kaasalainen et al, 2017;Kettunen et al, 2018;Rikkinen et al, 2018). Some of these fossils have since been used as minimum age constraints for dating phylogenies of Ascomycota Wedin, 2013, 2017;Beimforde et al, 2014).…”

“…However, recent studies have demonstrated that European Paleogene amber is a valuable source of fossils in some taxonomic and ecological groups within the Ascomycota. Such findings have already provided valuable new insights into the diversity and evolutionary history of sooty molds (Schmidt et al, 2014), lichensymbiotic and lichenassociated fungi (Hartl et al, 2015;Kaasalainen et al, 2015Kaasalainen et al, , 2017Kettunen et al, 2016Kettunen et al, , 2017, and calicioid lichens and fungi (Rikkinen and Poinar, 2000;Rikkinen, 2003b;Tuovila et al, 2013;Rikkinen et al, 2018).…”

“…However, in most cases, only vegetative mycelia are preserved without any reproductive structures. As the accurate taxonomic assignment of such specimens is usually impossible, relatively few amberpreserved fungal fossils have so far been assigned to extant lineages (Beimforde et al, 2014;Kettunen et al, 2015Kettunen et al, , 2018. However, recent studies have demonstrated that European Paleogene amber is a valuable source of fossils in some taxonomic and ecological groups within the Ascomycota.…”

How diverse were ferns in the Baltic amber forest?

“…Baltic amber is famous for the excellent preservation of organismic inclusions and represents a favorable source of Paleogene cryptogam fossils, such as liverworts, mosses, fungi, and lichens (Kettunen et al, , , , ; Kaasalainen et al, ; Heinrichs et al, ). Despite the excellent potential for preservation, ferns have only rarely been reported as inclusions from Baltic amber.…”