First report of permineralised plants in the Stephanian of Arnao (Asturias, northwestern Spain)

The first record of an anatomically preserved flora from Stephanian outcrops at Arnao beach (Asturias, Spain) is presented. The stratigraphic section is part of a geological heritage site that preserves exceptional Devonian reef deposits. The Carboniferous succession contains coal seams worked by one of the earliest mines in Spain and its plant-fossil assemblages were reported in the 19th century but scarcely revised later. The new assemblages recovered in the beach, during extreme low tides, represent the first record of permineralised trunks in northwestern Spain. Large cordaitalean specimens are referred to a new species of Cordaixylon characterised by non-septate pith, araucarian radial pitting of the tracheids and cross-fields with phyllocladoid pits. Part of the root mantle of Psaronius is preserved in water-worn pebbles, indicating the presence of tree ferns in the palaeoflora. The associated compression/impression assemblage includes lycophytes, sphenophytes, pteridosperms and pteridophytes. A comparison of the assemblage confirms its importance for reconstructing the Late Pennsylvanian floral succession in the region.