Land plants in the Devonian Villavicencio Formation, Mendoza Province, Argentina

Plant assemblages are described from two localities, San Isidro Creek and V aqueria, in the marine basal Devonian Villavicencio Formation in Mendoza Pr ovince, the Argentine Precordillera. Abundant smooth and more rarely axes w ith enations occur with rare fertile specimens and isolated swollen structu res interpreted as sporangia. Sterile 'leafy' axes are placed in a new morp hotaxon, Bowerophylloides, and a new genus, Isidrophyton, has been erected to accommodate sterile axes with vertically elongate, fusiform surface feat ures and terminal sessile sporangia borne in pairs. The plants are at simil ar grades of organisation to those in coeval assemblages elsewhere, but can not be assigned unequivocally to existing taxa. The locations of these Loch kovian assemblages are plotted on basal Devonian palaeocontinental reconstr uctions and it is concluded that the composition and the isolated position of the Argentina assemblages on the western margin of Gondwana at mid latit udes in a possibly cool temperate climate hint at a distinct phytogeographi c unit. (C) 2001 Elsevier Science B.V. All rights reserved.