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A new leaf inhabiting ascomycete from the Jurassic (ca 170 Mya) of Yorkshire, UK, and insights into the appearance and diversification of filamentous Ascomycota

Summary

Scientists discovered and described a new ancient fungus called Harristroma eboracense that lived on plant leaves about 170 million years ago during the Jurassic period. This fungus helps us understand how fungi diversified and evolved over time. By studying this fossil and comparing it with modern fungi, researchers learned that fungi began developing specialized structures for infecting plants during the Mesozoic era, and that they likely first thrived on broad-leaved plants in warm, wet forests.

Background

Leaf-associated fungi have a rich Cenozoic fossil record, but their earlier Mesozoic diversity is poorly characterized. Understanding the early diversification of filamentous Ascomycota requires careful analysis of rare leaf-inhabiting fossils from the Jurassic and Cretaceous periods. This study examines a newly discovered fossil fungus from Middle Jurassic deposits to understand the evolutionary origins of leaf-associated Ascomycota.

Objective

To describe and characterize a new leaf-associated fungus from the Middle Jurassic of Yorkshire, UK, and to place it within the context of fungal molecular phylogeny to understand the diversification of Mesozoic Ascomycota. The authors sought to identify when key morphological characters for fungal classification first appeared in the fossil record.

Results

A new genus and species, Harristroma eboracense, was identified as a Middle Jurassic leaf-associated fungus with melanized radiate stromata on cycadophyte cuticles. The fossil and others from the Jurassic and Cretaceous are likely related to Leotiomyceta. Early Cretaceous fossils represent the oldest evidence of perithecial Sordariomycetes and Dothideomycetes thyriothecia, with broad-leaved gymnosperms in warm temperate wet forests as the probable environment for early Leotiomyceta radiation.

Conclusion

Harristroma eboracense provides evidence for leaf-associated fungal colonization in the Middle Jurassic and contributes to understanding Mesozoic Ascomycota diversification. Key morphological characters including ostioles and appressoria first appear in the Mesozoic fossil record. The data suggest that warm temperate wet forests with broad-leaved gymnosperms, particularly cycadophytes, were the primary environment for early Leotiomyceta radiation.
  • Published in:IMA Fungus,
  • Study Type:Paleontological Description and Comparative Analysis,
  • Source: 10.1186/s43008-024-00162-9, PMID: 39501407
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