LesleyaLesquereux from the Pennsylvanian of the Iberian Massif: part of a dryland megaflora from the Variscan orogen, northwestern Portugal

Abstract

The Carboniferous – early Permian plant genus Lesleya is a characteristic component of “dryland floras” that occupied a wide range of moisture-stressed, well-drained environments in tropical regions of Euramerica. Fossil records of Lesleya are almost exclusively found in basinal lowlands. For example, occurrences in Early Pennsylvanian-age, seasonally dry, parautochthonous deposits in basinal lowlands of North America (e.g., Illinois Basin, USA) indicate that Lesleya lived in that region in low-altitude (lowland) paleoenvironments during dry climatic intervals. In this paper, we document the first occurrence of Lesleya during the Carboniferous on the Iberian Massif, in lower Gzhelian (Upper Pennsylvanian) strata of the Douro Carboniferous Basin, in northwestern Portugal. This newly discovered occurrence includes a new species, Lesleya iberiensis sp. nov., recognized on the basis of natural molds of leaves. The Portuguese Lesleya fossils are from upland intramontane deposits and occur between coal beds. Their fossil remains are preserved in mica-rich shales that were deposited between sandstone-dominated fluvial and shale-dominated lacustrine deposits, suggesting that this megaflora was deposited near freshwater bodies. These new data provide evidence that this megaflora grew in mountain riparian environments within the Variscan orogen, either in localized, well-drained areas or during drier climatic intervals in the Late Pennsylvanian.