A marattialean fern with in situ spores, Cyathocarpus benefoliatii sp. nov., from the Lopingian of Southwest China

A species of adpressed marattialean fern having pinnules with fertile organs, Cyathocarpus benefoliatii Yu.Guo, Zhou et Z.Feng sp. nov., is established from the Lopingian (upper Permian) of eastern Yunnan Province, Southwest China. Fronds of this new species are at least tripinnate, with alternately arranged penultimate pinnae, alternately or suboppositely arranged ultimate pinnae, and alternately arranged pinnules. Fertile pinnules are linguiform in shape and abaxially bear a row of 4–7 synangia tightly arranged on each side of the midvein from the base to the apex. Synangia are ovoidal, radially symmetrical, and individually consists of 4 or 5 exannulate sporangia. Sporangia are ovoidal and laterally fused along most or all of their length. The inner-facing sporangial wall has one layer of cells, while the outer-facing sporangial wall has three layers of cells. In situ spores of the Laevigatosporites/Latosporites type are 43–61 μm in diameter, monolete, and laevigate. The exine encompasses a perine, a sexine, and a nexine. These characteristics indicate that Cyathocarpus benefoliatii sp. nov. belongs to the Pecopteris trevirani Group (palynological grouping) of Paleozoic marattialeans.