Aculeovinea yunguiensis Gen. et Sp. Nov. (Gigantopteridales), a New Taxon of Gigantopterid Stem from the Upper Permian of Guizhou Province, China

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Abstract
Permineralized gigantopterid stems of Aculeovinea yunguiensis 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 are narrow and covered with prickles, and contain a parenchymatous cortex with sparganum‐type fibrous strands, an endodermis‐like layer, variable amounts of secondary xylem, a eustele of mesarch primary vascular bundles, and a parenchymatous pith. The stems are vesselless, and tracheids of the protoxylem have annular, helical, scalariform, or reticulate thickenings, while the metaxylem tracheids have scalariform to transversely elongated bordered pits. The secondary xylem has nearly storied tracheids with bordered pits that are commonly multiseriate, alternately arranged, and more or less transversely elongated but are occasionally uniseriate scalariform. Heteroseriate rays and scattered axial parenchyma in single‐celled columns also are found 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 Gigantonoclea 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 unique 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.