Fungal spores and fruiting bodies from Miocene deposits of the Pelotas Basin, Brazil

Abstract Most of the palynological information from pre-Quaternary deposits of the Pelotas Basin, Southmost Brazil, refers to sporomorphs and dinoflagellate cysts. Fungal microfossil records are poorly detailed, and underutilized as biostratigraphic indexes or paleoenvironmental indicators. This work is derived from an extensive palynological analysis of 28 samples of cores from two wells (BP-01 and CBM001-ST-RS), corresponding to the Imbe and Cidreira formations, Miocene of this basin. Assemblages with fossilized remains of fungi, both as spores and fruiting bodies, have been recovered, totalizing 89 taxa, including 21 assigned to Amerosporae, 13 to Didymosporae, 28 to Phragmosporae, seven to Dictyosporae, two to Staurosporae and 18 related to Microthyriales. Majority of the species identified is recorded for the first time in Brazil, and compared to the fungi assemblages recorded in Cenozoic deposits from Argentina, USA, Canada, China and India, widening, therefore, their paleogeographic distribution. The occurrence of Phragmothyrites eocaenicus , Plochmopeltinites cooksoniae , P. masonii , Asterothyrites menonii , Trichothyrites amorphus and Parmathyrites ramanujamii , associated to data from other microfossil groups have indicated a Miocene age for the studied sections. A marine setting during the deposition is substantiated by the expressive amount of both dinoflagellate cysts and microforaminiferal linings. The presence of microthyriaceous fungi associated to pteridophytic spores and remarkable occurrence of Podocarpidites spp., reinforce the hypothesis of continental origin in a humid non-tropical climate.