Format: ORAL

Giovanni C. Nunes1, Louise Egerton-Warburton2, Patrick S. Herendeen2, Niiden Ichinnorov3, Gongle Shi4, Peter R. Crane5,6, Fabiany Herrera7

1 Egidio Feruglio Paleontological Museum, Trelew, Argentina 2 Chicago Botanic Garden, Chicago, IL, USA 3 Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar–15160, Mongolia 4 State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China 5 School of Forestry and Environmental Studies, Yale University, New Haven, United States of America 6 Oak Spring Garden Foundation, Oak Spring, Upperville, Virginia 20184, USA 7 Earth Sciences, Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA

A preliminary report of fungal remains associated with leaves of different gymnosperm taxa is presented in this study. The fossils were recovered from lignites collected at the Early Cretaceous Tevshiingovi Formation (~120 Ma Aptian-Albian) in Central Mongolia. This contribution also explores the different techniques used for recovering the fungal remains from the lignites. Around 450 specimens of leaves of several gymnosperm lineages (i.e., ginkgophytes, corystosperms, conifers) were analyzed using multiple complementary techniques (i.e., light microscopy, epifluorescence, SEM, and X-ray computer microtomography). For observations under light microscopy, most of the samples were previously bleached, applying a modified protocol for chemical treatment of fossil cuticles (with both H2O2 and KOH). Staining of the fungal remains with different stains (e.g., safranin, cotton blue, congo red) for enhancing critical features was also explored. Abundant nonreproductive and reproductive remains of epiphyllous fungi are associated with the cuticular surface of around 70% of the specimens. The most conspicuous and abundant structures are scattered to densely distributed thyriothecium-like ascomata, which are mostly associated with the leaves of ginkgophytes and corystosperms. Additional remains include septate hyphae, often with appressoria, 1-3 septate phragmospores, scolecospores, and perithecia with associated filamentous mycelium. These fungal remains are attributable to epiphyllous, probably saprobic, fungi within different lineages of Ascomycota (e.g., Dothideomycetes, Sordariomycetes) and other incertae sedis taxa. This report represents the first steps in documenting the fungal diversity associated with the leaves of gymnosperms and in the characterization of the ecological relationships between different organisms from the Early Cretaceous swamp forests of Mongolia. Exploring different complementary techniques demonstrates an improvement in recovering fungal remains from lignite samples.More importantly, the abundance and well preservation of the fossil fungi will help recognize different developmental structures and features of the epiphyllous community.