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The Green River Formation of Wyoming, USA, is host to the world’s largest known lacustrine sodium carbonate deposits, which accumulated in a closed basin during the early Eocene greenhouse. Alkaline brines are hypothesized to have been delivered to ancient Gosiute Lake by the Aspen paleoriver that flowed from the Colorado Mineral Belt. To precisely trace fluvial provenance in the resulting deposits, we conducted X-ray fluorescence analyses and petrographic studies across a suite of well-dated sandstone marker beds of the Wilkins Peak Member of the Green River Formation. Principal component analysis reveals strong correlation among elemental abundances, grain composition, and sedimentary lithofacies. To isolate a detrital signal, elements least affected by authigenic minerals, weathering, and other processes were included in a principal component analysis, the results of which are consistent with petrographic sandstone modes and detrital zircon chronofacies of the basin. Sandstone marker beds formed during eccentricity-paced lacustrine lowstands and record the migration of fluvial distributary channel networks from multiple catchments around a migrating depocenter, including two major paleorivers. The depositional topography of these convergent fluvial fans would have inversely defined bathymetric lows during subsequent phases of lacustrine inundation, locations where trona could accumulate below a thermocline. Provenance mapping verifies fluvial connectivity to the Aspen paleoriver and to sources of alkalinity in the Colorado Mineral Belt across Wilkins Peak Member deposition, and shows that the greatest volumes of sediment were delivered from the Aspen paleoriver during deposition of marker beds A, B, D, and I, each of which were deposited coincident with prominent “hyperthermal” isotopic excursions documented in oceanic cores. 

Species of the genus Phaeohelotium ( Leotiomycetes : Helotiaceae ) are cup fungi that grow on decaying wood, leaves, litter, and directly on soil. Northern Hemisphere species are primarily found on litter and wood, whereas in the Southern Hemisphere the genus includes a mix of saprotrophs as well as taxa that grow on soil in association with ectomycorrhizal trees. The diversity of this genus has not been fully explored in southern South America. Here we describe two species from Chile, Phaeohelotium maiusaurantium sp. nov . and Ph. pallidum sp. nov ., found on soil in Patagonian Nothofagaceae -dominated forests. We present macro- and micromorphological descriptions, illustrations, and molecular phylogenetic analyses. The two new species are placed in Phaeohelotium with high support in our 15-locus phylogeny as well as phylogenetic reconstructions based on the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene. Our ITS phylogeny places both Ph. maiusaurantium and Ph. pallidum in a well-supported subclade that includes ectomycorrhizal root tip samples from Australasia. Similar species can be separated from these new taxa based on morphological characteristics, biogeography, substrate, and sequence data. In addition, two unnamed species from Chilean Nothofagaceae forests ( Phaeohelotium sp. 1 and Phaeohelotium sp. 2) are documented from scant collections and sequence data and await description until more material becomes available. 

Amylascusis a genus of ectomycorrhizal truffles withinPezizaceaethat is known from Australia and contains only two described species,A. herbertianusandA. tasmanicus. Species ofAmylascusare closely related to truffles (Pachyphlodes,Luteoamylascus) and cup fungi (Plicariella) from the Northern Hemisphere. Here we reevaluate the species diversity ofAmylascusand related taxa from southern South America and Australia based on new morphological and molecular data. We identify previously undocumented diversity and morphological variability in ascospore color, ascospore ornamentation, hymenial construction, epithecium structure and the amyloid reaction of the ascus in Melzer’s reagent. We redescribe twoAmylascusspecies from Australia and describe seven newAmylascusspecies, five from South America and two from Australia. This is the first report ofAmylascusspecies from South America. We also describe the new South American genusNothoamylascusas sister lineage to thePachyphlodes-Amylascus-Luteoamylascusclade (includingAmylascus,Luteoamylascus,Pachyphlodes, andPlicariella). We obtained ITS sequences of mitotic spore mats fromNothoamylascus erubescensgen. & sp. nov. and four of the seven newly describedAmylascusspecies, providing the first evidence of mitotic spore mats inAmylascus. Additional ITS sequences from mitotic spore mats reveal the presence of nine additional undescribedAmylascusand oneNothoamylascusspecies that do not correspond to any sampled ascomata. We also identify three additional undescribedAmylascusspecies based on environmental sequences from the feces of two ground-dwelling bird species from Chile,Scelorchilus rubeculaandPteroptochos tarnii. Our results indicate that ascomata fromAmylascusandNothoamylascusspecies are rarely collected, but molecular data from ectomycorrhizal roots and mitotic spore mats indicate that these species are probably common and widespread in southern South America. Finally, we present a time-calibrated phylogeny that is consistent with a late Gondwanan distribution. The time since the most recent common ancestor of: 1) the familyPezizaceaehad a mean of 276 Ma (217–337 HPD); 2) theAmylascus-Pachyphlodes-Nothoamylascus-Luteoamylascusclade had a mean of 79 Ma (60–100 HPD); and 3) theAmylascus-Pachyphlodesclade had a mean of 50 Ma (38–62 HPD). The crown age ofPachyphlodeshad a mean of 39 Ma (25–42 HPD) andAmylascushad a mean age of 28 Ma (20–37 HPD), falling near the Eocene-Oligocene boundary and the onset of the Antarctic glaciation (c. 35 Ma).