New insights into the South China Lower Devonian flora based on fossils from Hezhang, Guizhou Province.

The Early Devonian flora of South China is composed of many endemic members and has been studied mainly based on Yunnan materials. We in this study report a new Lower Devonian plant locality, recognize four sub-regions of the Early Devonian flora from South China and furthermore demonstrate these plants' distribution pattern and probable dispersal route. The new finds of plant fossils are from the Lower Devonian of Hezhang County, Guizhou Province, and include Zosterophyllopsida Demersatheca and Euphyllophytopsida Pauthecophyton. Demersatheca contigua, consisting of cylindrical strobili with four longitudinal rows of sporangia decussately arranged, shows great similarities to the plant from Yunnan and Guangxi localities. Pauthecophyton hezhangensis sp. nov. has distinct fertile units with grouped sporangia and each unit with two or three fusiform sporangia. The new locality belongs to the Guizhou sub-region and shares some taxa with the eastern Yunnan and Cathaysia sub-regional floras within South China, in which the shared plant members are distributed around the epicontinental sea. We suggest that the Guizhou sub-region might act as a bridge during plant dispersal from eastern Yunnan to Cathaysia Oldland in the Early Devonian. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.