First fossil record of Castanopsis (Fagaceae) from the middle Miocene Fotan Group of Fujian, southeastern China

Fagaceae have a long fossil history that can be dated back to the Late Cretaceous. They are the key element of several distinct biomes found throughout the Northern Hemisphere; therefore, it is a prime candidate for modern biogeographic analysis. Castanopsis (Fagaceae) species are the dominant trees of subtropical evergreen broad-leaved forests and some tropical forests. They are used for timber and have medicinal and edible uses. Here, we describe two species, Castanopsis zhoui sp. nov. and C. cf. chinensis, based on fossil leaves with cuticle features recovered from the middle Miocene of Fujian Province, Southeast China. Our fossils enrich the Neogene fossil record of this genus in regions that contain the greatest diversity of its extant species in China and southern and southeastern Asia. Castanopsis species grow today in tropical to subtropical evergreen forests with a mean annual temperature ranging from 13 °C to 27 °C. The occurrence of Castanopsis zhoui sp. nov. and C. cf. chinensis confirms previous paleoclimate estimates of Zhangpu flora using the leaf physiognomy method.