A new species of Cyathocarpus with in situ spores from the lower Permian of Gansu, northwestern China

摘要

Well-preserved Marattialean fertile fronds are analyzed in this paper that come from the Cisuralian Shanxi Formation of Yongchang, Gansu Province, northwestern China. In particular, synangium in fronds and in situ spores are analyzed in the lab. Data show that the synangium of this species contains between four and five radially arranged pedicellate sporangia. The spores of this plant are small, between 21 and 30 mu m, monolete and microgranulate with no visible annule. The fossils presented in this study are included within the genus Cyathocarpus. Furthermore, these spore masses and spores in situ of this genus are described in detail at the first time as a component of the Cathaysian flora. Based on comparisons with previously reported fossil records of these plants, we determined a series of differences. Thus, the fossils presented here are referred to a new species. In addition, the reproductive organs of the new fossils described in this paper provide some valuable taxonomic information. Based on the paleogeographic distribution of Cyathocarpus and the position of paleoplates in Late Paleozoic, we speculated that one of the possible migrated routes of Cyathocarpus is from the Euramerica to the North China Block and Alashan Terrane, terminating in the South China Block.