Evidence of Ascomycete Hyphae on a Pennsylvanian Fern Compression, Czech Republic

Abstract The paper documented, branched hyphae preserved on the adaxial cuticle of pinnules of the Pennsylvanian leptosporangiate fern Discosoropteris chlupatum Pšenička et al. from the Whetstone Horizon, Radnice Member, Kladno Formation of the Pilsen Basin, Czech Republic. The hyphae occur as running structures on the leaf surface, show simple septa and lack clamp connections, consistent with an ascomycete affinity. Exceptional host-tissue preservation indicates rapid burial by volcanic ash and supports epiphyllous colonisation, most plausibly parasitic, although early saprotrophic colonisation cannot be excluded. This record expands the limited evidence of Paleozoic foliar fungi preserved as compressions and highlights the potential of volcaniclastic deposits for detecting plant–fungus associations.