A contribution to the knowledge of the Triassic fern genus Symopteris

Several European species of the Triassic fern genus Symopteris Xu are studied and the genus is subsequently subject to revision. Moreover, the botanical affinity of the genus is discussed and its relation to the Marattiales debated. Symopteris fronds have a typical fasciculate venation, usually a crenulate pinnule margin and contracted pinnule bases; in addition, the margin of the fertile pinnules is recurved to supposedly protect the sporangia. Most of the fossils have originally been attributed to the genus Bernoullia Heer, a junior synonym of Bernoullia Oliver (extant Bombacaceae). So far, eight species could be identified, three from Europe [Symopteris helvetica (Heer) Xu in Xu et al., Symopteris lunzensis (Stur ex Krasser) Xu in Xu et al., Symopteris rumpfii (Schenk) nov.comb.], one from Kazakhstan (Symopteris aktjubensis Brik) and four from East Asia [Symopteris zeilleri (P’an) Xu in Xu et al., Symopteris pecopteroides (Feng et al.) nov. comb., Symopteris densinervis Xu et Duan in Xu et al., Symopteris pseudolobifolia (Yang in Chen et al.) nov. comb.]. One additional species assigned earlier to Bernoullia (i.e. Bernoullia waehneri Stur) has to be attributed to another genus. The oldest known representatives of Symopteris occurred in the Ladinian of Europe; during the Upper Triassic, the genus increased in species number in Europe and Asia, while the latest occurrence is in the Rhaetian of Vietnam.