Extending the fossil record for foliicolous Dothideomycetes: Bleximothyrium ostiolatum gen. et sp. nov., a unique fly‐speck fungus from the Lower Cretaceous of Virginia, USA

PREMISE Fossils can reveal long-vanished characters that inform inferences about the timing and patterns of diversification living fungi. Through analyzing well-preserved fossil scutella, shield-like covers fungal sporocarps, we describe a new taxon early Dothideomycetes with combination unknown among extant taxa. METHODS Macerated clays from Potomac Group, lower Zone 1, Lower Cretaceous (Aptian, 125–113 Ma) Virginia USA yielded one gymnospermous leaf cuticle colonized by 21 sporocarps single morphotype. We inferred tree nuclear ribosomal DNA species, coded morphological to evaluate alternative, equally parsimonious placements in molecular constraint species. RESULTS Bleximothyrium ostiolatum gen. et sp. nov. has an ostiolate scutellum radiate, dichotomizing hyphae. Unlike otherwise similar taxa, B. tangled hyphae at its margin. Scutella are connected superficial mycelium, intercalary lateral appressoria, extensive subcuticular “mycélium en palmettes”. The host consistent identity as non-papillate ginkgophyte or cycad. CONCLUSIONS is oldest known fly-speck fungus occurs on plant cuticles only Dothideomycetes. Its characters, margin, mycélium palmettes other likely represents group fungi may now be extinct.