Aculeovinea yunguiensis gen. et sp nov. (Gigantopteridales), a new taxon of gigantopterid stem from the Upper Permian of Guizhou Province, China

Permineralized gigantopterid stems of Aculeovinea yungtriensis Li et Taylor gen. et sp. nov. were collected from the Upper Permian of western Guizhou, China, and prepared with the cellulose acetate peel technique. The stems a re narrow and covered with prickles, and contain a parenchymatous cortex wi th sparganum-type fibrous strands, an endodermis-like layer, variable amoun ts of secondary xylem, a eustele of mesarch primary vascular bundles, and a parenchymatous pith. The stems are vesselless, and tracheids of the protox ylem have annular, helical, scalariform, or reticulate thickenings, while t he metaxylem tracheids have scalariform to transversely elongated bordered pits. The secondary xylem has nearly storied tracheids with bordered pits t hat are commonly multiseriate, alternately arranged, and more or less trans versely elongated but are occasionally uniseriate scalariform. Heteroseriat e rays and scattered axial parenchyma in single-celled columns also are fou nd in the wood. From a different site of western Guizhou, a compressed axis comparable to the permineralized stems was found connected to a pair of Gi gantonoclea blades. This connection and anatomical similarities between the co-preserved permineralized stems and permineralized Gigantonoclea leaves allow for a reconstruction of the plant. Aculeovinea yunguiensis is a uniqu e seed plant, and its slender stems and large leaves indicate that it had a vine-liana habit and had grown in the Permian tropical rain forests.