J Syst Evol ›› 2015, Vol. 53 ›› Issue (6): 499-511.DOI: 10.1111/jse.12145

• Research Articles • Previous Articles     Next Articles

Late Miocene Palaeocarya (Engelhardieae: Juglandaceae) from Southwest China and its biogeographic implications

Hong‐Hu Meng1,3, Tao Su1, Yong‐Jiang Huang2, Hai Zhu2,3, and Zhe‐Kun Zhou1,2*   

  1. 1Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, China
    2Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
    3University of Chinese Academy of Sciences, Beijing, China
  • Received:2014-10-20 Published:2015-03-30

Abstract: Fossil fruits of Palaeocarya (Juglandaceae) are described from late Miocene sediments of southeastern Yunnan, China. The fruits present a tri-lobed wing consisting of an intact oblong-ovate middle lobe and two lateral lobes. The lobes are apically obovate, and have pinnate venation. The middle lobe is thicker at the base and gradually tapers to the apex. The nutlet, located at the base of the winged fruit, is round and hispid, and is subdivided by a septum into two compartments. Based on extensive morphological comparisons to previously documented fossil fruits, we found that the fossil fruits align most closely with members of the genusPalaeocarya, but have a unique combination of characters. Thus, we describe the fossils as a new species, Palaeocarya hispida sp. nov. This species represents an important range expansion for low-latitude occurrences of Palaeocarya in the late Miocene and therefore substantially improves our understanding of the biogeographic history of the genus. We propose that the wide distribution of Palaeocarya and relatively narrow distributions of close relatives, Engelhardia, Alfaropsis, and Oreomunnea, might be associated with a stepwise cooling and a major ice sheet expansion in the Antarctic and Arctic from the late middle Miocene to early Pliocene. In particular, the climatic oscillations during the Quaternary, such as the last glacial maximum, might have led to a decrease in the geographic distribution of Engelhardieae.

Key words: biogeography, Engelhardieae, fossil fruit, Juglandaceae, late Miocene, Palaeocarya