Bisigillariostrobus prolificus gen. et sp. nov., new sigillarian bisporangiate strobili from the early Permian of Wuda coalfield, Inner Mongolia, China

A new genus of bisporangiate sigillarian strobili Bisigillariostrobus with the only species Bisigillariostrobus prolificus is proposed. A large number of strobili originates from the Wuda area in Inner Mongolia, China, fossilized during the early Permian period. The specimens are preserved in volcanic tuff, allowing for the study of both morphology and anatomy. The strobili are pedunculate, cylindrical with helically arranged sporophylls. The megasporophylls are on the basal part and microsporophylls on the apical part with each retaining single adaxial sporangium. The sporophylls have a long pedicel and lateral alations, and abaxial heel on the transitional part and a long distal lamina. In situ megaspores are of the Sublagenicula nuda type and microspores are assigned to the dispersed miospore species Crassispora kosankei. Some ontogenetic stages of strobili and megaspores are described. Sublagenicula and Crassispora-producing sigillarians are given and compared with the current species.