Unusual preservation of a microthyriaceous fungus (Ascomycota) on Sphenobaiera (ginkgophyte foliage) from the Middle Jurassic of China

Leaves today are inhabited by a wide variety of fungi, typically ascomycetes, but also some basidiomycetes and zygomycetes. Little is known to date regarding the fungi that colonized the leaves of fossil plants older than Cretaceous. In this paper we describe ascomycete fruiting bodies (ascomata) that are present on the adaxial surface of a Sphenobaiera (Ginkgophyta) leaf from a Middle Jurassic deposit near Daohugou village, Inner Mongolia, China. The ascomata are identified as imprints in the leaf cuticle, with only parts remaining of the actual body fossil. Fruiting bodies are scutate, spherical in outline, and consist of three distinct zones delimited by the size and arrangement of the hyphae. The morphology is suggestive of geologically younger microthyriaceous ascomata, especially Asterothyrites, Microthyriacites, and Trichothyrites. This discovery represents the oldest fossil evidence of microthyriaceous fungi inhabiting ginkgophytes.