The occurrence of Potamomyces palmarensis sp. nov. in the Late Holocene at the El Palmar National Park (Colón, Entre Ríos, Argentina) and transfer of fossil species of Mediaverrunites to Potamomyces

NUÑEZ OTAÑO, NOELIA; DI PASQUO, M.M.; BIANCHINOTTI, M.V.

PALYNOLOGY

AMER ASSOC STRATIGRAPHIC PALYNOLOGISTS FOUNDATION

Año: 2017 vol. 41 p. 267 - 277

0191-6122

We present the first record of Potamomyces Hyde (Ascomycota, Dothideomycetidae) from soilsediments of the El Palmar National Park, Entre Rıos, Argentina. Nineteen samples were taken (each24 cm from the surface) of a 80 cm thick core composed of a homogeneous lithology of argillaceousfine-grained sands. This taxon was only identified in the basal sample of the core (371 § 30 years BP),located in a palm area (Butia yatay) with a semi-dense herbaceous-shrub layer. We propose anamendment of the generic diagnosis based on the revision of the species described up to now, and ofa new one here defined (P. palmarensis). Additionally, we confirm that the morphotaxonMediaverrunites Jarzen & Elsik ex Nandi & A. Sinha is its junior synonym, so we propose newcombinations for seven species. We recommend the use of this natural taxon instead of themorphotaxon in future contributions. In terms of the geographical and stratigraphical distribution ofPotamomyces, our record is the first mentioned for Argentina and the southernmost for SouthAmerica. Based on its ecological requirements, a humid sub-tropical environment and abundantorganic matter in the soil are suggested for the Latest Holocene of the study region. This hypothesis issupported by current knowledge of regional climatic and environmental conditions for the study areaduring the short humid interval of the Little Ice Age.