First fossils of Zygogynum from the Middle Miocene of Central Yunnan, Southwest China, and their palaeobiogeographic significance

The collision of Gondwana and Laurasia effected plant exchanges between the two continents and thus affected the evolution of the flora of Yunnan, Southwest China. Consequently, the plant diversity in Yunnan has been enriched such that it has attracted the attention of botanical researchers. In this paper, we describe winteraceous fossil leaves collected from the Middle Miocene in Central Yunnan. Compared with the leaves of today's plants, they share cuticular features and leaf morphological characters with Zygogynum Baillon (Winteraceae); the fossil plant is designated as a new species, Zygogynum poratus n. sp. Liang and Zhou. Based on its historical and recent distribution, the genus probably had migrated into Yunnan from Gondwana during or before the Middle Miocene, spreading beyond its current geographic range.