Anatomically preserved lepidodendralean plants from lower permian coal balls of northern China: Achlamydocarpon intermedium sp. nov

Lepidodendralean lycopsids, a dominant component in Late Palaeozoic wetland plant communities, possess a diversity of reproductive structures that are primarily known from the Late Palaeozoic floras of Europe and North America. Here we document an anatomically preserved lepidodendralean lycopsid sporophyll with attached megasporangium from the Lower Permian Taiyuan Formation in Shanxi Province, northern China. The sporophyll has a pedicel onto which the sporangium is attached, and the sporangium is dorsiventrally flattened, proximally dehiscent and longitudinal ridged. The megasporangial wall comprises three zones: an outer uniseriate layer of columnar cells, a middle layer 1-3 cells thick comprising isodiametric parenchymatous cells, and an inner zone 1-3 cells thick of thick-walled cells. The vascular system comprises a single xylem strand surrounded by zone of parenchyma that continues through the pedicel into the lamina. Within the megasporangium a single functional megaspore and three abortive megaspores occur. Features of this specimen conform to Achlamydocarpon Schumacher-Lambry, and comparisons with other species show it shares similarities with A. takhtajanii (Sni.) Schumacher-Lambry and A. varius Taylor and Brack-Hanes. Although the morphology and anatomy of the specimen we describe overlaps with these two species, it is distinct from both leading to the erection of the new species A. intermedium sp. nov. The evolutionary significance of A. intermedium sp. nov. and the identity of its parent plant are considered, and the status and systematic position of "Oriental lepidophytes" from the Cathaysian floras are discussed.