A new cycad trunk from the Palaeocene in the Neuquén Basin, Patagonia (Argentina)

Abstract

To date only two genera of cycad stems have been described from Cenozoic strata (Bororoa and Menucoa). We describe a new species of Wintucycas, Wintucycas beatrizae sp. nov. (Encephalartoideae), from the basal Palaeogene of Patagonia. The new species is based on anatomically preserved mature cycadalean stems which have been recovered from the Pichaihue Limestones (Neuquén Basin, Patagonia, Argentina). The new species is characterized by the presence of a columnar stem with an armor of persistent leaf bases, vascular bundles displaying an omega pattern, the absence of cataphylls, a wide pith with medullary vascular bundles, mucilage canals and idioblasts, a polyxylic vascular cylinder, inverted xylem, and manoxylic wood. The presence of W. beatrizae sp. nov. in the Pichaihue Limestones suggests warm climate conditions during the early Palaeogene in the Neuquén Basin, and also extends the range of this genus of Cycadales (Encephalartoideae) into the Cenozoic.