Fossil Fungi from Miocene Sedimentary Rocks of the Central and Coastal Amazon Region, North Brazil
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摘要

Samples from outcrops of the Miocene Solimões and Barreiras formations from the central and coastal Amazon regions of Brazil were analyzed palynologically. Assemblages of fossil fungi were identified, and are described herein, and their relevance to paleoenvironmental and paleoclimatic studies in tropical regions discussed. The fungal assemblage comprises four spore groups, 19 species belonging to 12 genera. Additionally, two new species are proposed. The samples from the Solimões Formation contain the following taxa: m>Mediaverrunites elsikiim>, m>Mediaverrunites mullerim>, m><span class="named-content genus-species" id="named-content-1">Monoporisporitesspan>m> sp., m>Fusiformisporites crabbiim>, and m>Multicellites cingulatusm>. The presence of these suggests river channel margins colonized by freshwater vegetation, where seasonal fluctuations of water table and rainfall produce wetter substrates. The samples from the Barreiras Formation showed higher species and generic diversity than those from the Solimões Formation with m>Hypoxylonites minutusm>, m><span class="named-content genus-species" id="named-content-2">Hypoxylonsporites ater, Hypoxylonitesspan>m> sp., the new species m><span class="named-content genus-species" id="named-content-3">Inapertisporites multiporusspan>m> n. sp., m>Pluricellaesporites regularism>, m>Lacrimasporonites levism>, m>Monoporisporites annulatusm>, m>Spirotremesporites simplexm>, m>Dyadosporites novusm>, m><span class="named-content genus-species" id="named-content-4">Dyadosporitesspan>m> sp., and m>Multicellaesporites attenuatesm>. All of these correspond to parasitic fungi from a range of from tropical wetlands. m><span class="named-content genus-species" id="named-content-5">Spegazzinitesspan>m> sp. and m>Dicellaesporites aculeolatusm>, good indicators of marine influence and mangrove presence, were also identified in the samples from the Barreiras Formation. Furthermore, the fungal spore taxa m>Inapertisporites multiporusm>, m>Mediaverrunites elsikiim>, m>Mediaverrunites mullerim>, m>Pluricellaesporites regularism>, and m>Spirotremesporites simplexm> serve as stratigraphic indicators when combined with miospore index taxa such as m>Crassoretitriletes vanraadshoovenim>, m>Grimsdalea magnaclavatam> and m>Fenestrites longispinosusm> indicating a Miocene age for these sediments in the Amazon region.

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