Frond reconstruction of <i>Polymorphopteris mei</i> sp. nov. from the early Permian Wuda Tuff Flora with insights into its taphonomy

Ancient forests preserved in growth position by rapid sedimentological burial (T⁰ assemblages) constitute exceptionally valuable fossil repositories, especially those covered by fine-grained volcanic ash (tuff) that may preserve plant morphology and anatomy in high-fidelity. This study documents the frond morphology and anatomy of a new species, <i>Polymorphopteris mei</i> sp. nov. from the Wuda Tuff Flora, an <i>in situ</i> fossil forest Lagerstätte of early Permian age from Inner Mongolia, China preserved by volcanic ash. The frond of <i>P. mei</i> is tripinnate, composed of three types of penultimate pinnae and three types of ultimate pinnae. Anatomical features of the frond and penultimate rachises correspond to the stewartiopterid-type leaf trace configuration characteristic of the Marattiales fern evolutionary stem-group family Psaroniaceae. Pyrite-infilled pore-like structures within the rachises are identified as possible evidence of post-mortem fungal action. This study enhances our understanding of the morphology, anatomy, systematic affinity and taphonomy of <i>P. mei</i> and its ecological context in the early Permian peat-forming communities of Cathaysia.