Eoguptioxylon antiqua gen. et sp nov (Pteridospermae) from the Upper Permian (La Antigua Formation), La Rioja Province, Argentina

A polystelic pteridosperm wood with steles irregularly disposed in ground parenchyma from the Upper Permian La Antigua Formation (La Rioja province) is described. The steles are surrounded by sclerenchymatic tissue. Each stele has preserved a central diaphragm pith with lacunes, primary and secondary xylem. The taxon is compared with Carboniferous-Permian Medullosales (Medullosa), Jurassic Pentoxylales (Pentoxylon, Nipanioxylon) and the incertae sedis genus Guptioxylon. Other anatomical characteristics, like picnoxylic secondary wood with uni- to biseriate pits, araucarioid cross-fields and the type of rays are shared with Coniferales. The genus described herein mostly resembles Guptioxylon from the Rajmahal Hills (India). However, the studied specimens cannot be adscribed to this taxon because of marked differences in the pith and the secondary xylem, departure and conformation traces, and the absence of a X-shaped peculiar periderm. Consequently a new genus and species are proposed to include this new Pteridosperm from the Upper Permian of Argentina: Eoguptioxylon antiqua gen. et sp. nov.