Extending the Fossil Record of Zygosporiaceae: Zygosporium bivesiculam sp. nov., a Unique Extinct Foliicolous Asexual Fungus Recovered From the Siwalik of India

Here, we report and describe a new foliicolous fossil species of Zygosporium (Zygosporiaceae: Xylariales: Sordariomycetes) on a compressed unidentified dicot leaf from the Siwalik sediments (Late Miocene; ca. 12–8 Ma) of Himachal Pradesh, western Himalaya. This unique fossil species, designated as Z. bivesiculam sp. nov., is characterized by macronematous, septate, unbranched conidiophore with a sterile true seta and a chain of two integrated, dark brown, curved, thick‐walled, swollen, laterally arranged vesicular cells along one side of the conidiophore in the opposite direction. Its vesicular morphological characteristics are unknown in both extant and extinct fungal species of Zygosporium , and so Z. bivesiculam likely represents a novel asexual foliicolous fungus that may now be extinct. This distinctive evidence could be crucial for the evolution of Zygosporium .