A new species of Scolecopteris (Marattiales, Psaroniaceae) from the early Permian Wuda Tuff Flora

New marattialean specimens with anatomically preserved fertile organs were collected from the upper part of Taiyuan Formation in the Wuda Coalfield, Inner Mongolia, China. Fertile and vegetative fronds are at least tripinnate. Fertile pinnules margins are entire and strongly enrolled to envelop 5-8 synangia along each side of the midvein. Individual synangium is attached to each lateral vein by an unvascularised pedicel. Synangia are radially symmetrical with 3-4 ovoid sporangia. The outer facing wall of the sporangium is 2-3 layers of undifferentiated cells. In situ spores are monolete with microechinate ornamentation, 20-40 μm in diameter. Vegetative pinnules are of Pecopteris hemitelioides-type. The unlobed extension of lateral margin and the unvascularised composition of pedicel in the fertile pinnules of the studied specimens are well consistent with the circumstance of the Oliveri Group within Scolecopteris as defined by previous authors. The combination of other features such as the undifferentiated outer facing sporangial wall cells, and the monolete in situ spores makes these specimens distinct from all other previously documented Scolecopteris species, necessitating the creation of a new species, Scolecopteris zhoui. S. zhoui represents the third well-established Scolecopteris species in the background forest community, and the diversity of Scolecopteris could be strikingly higher in considering two additional undescribed Scolecopteris species. The five groups of Scolecopteris, namely the Altus Group, the Oliveri Group, the Shanxiensis Group, the Minor Group and the Latifolia Group may represent types successively from primitive to derived.