J Syst Evol ›› 2019, Vol. 57 ›› Issue (2): 169-179.DOI: 10.1111/jse.12452

• Research Articles • Previous Articles     Next Articles

Occurrence of Christella (Thelypteridaceae) in Southwest China and its indications of the paleoenvironment of the Qinghai–Tibetan Plateau and adjacent areas

Cong-Li Xu1,3, Tao Su1,3*, Jian Huang1, Yong-Jiang Huang2, Shu-Feng Li1, Yi-Shan Zhao4, and Zhe-Kun Zhou1,2   

  1. 1Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla 666303, Yunnan, China
    2Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
    3University of the Chinese Academy of Sciences, Beijing 100049, China
    4Faculty of Electronic and Mechanical Engineering, Hunan University of Science and Technology, Xiangtan 411201, Hunan, China
  • Received:2017-12-22 Accepted:2018-07-12 Online:2018-07-25 Published:2019-03-01

Abstract: The uplift of the Qinghai–Tibetan Plateau dramatically changed the regional topography and climate, profoundly impacting the distribution of many plant lineages. Plant responses to environmental changes are particularly prominent in lineages that require ecological factors differentiated from those present before the uplift of the QTP. Two fossil occurrences of Christella H. Lév., Fl. Kouy–Tchéou (Thelypteridaceae), a fern genus now distributed mainly at low elevations of the pantropics with warm and moist habitats, are described based on fossilized Cenozoic leaf fronds recovered from SW China: late Paleocene Christella nervosa (J. R. Tao) C. L. Xu, T. Su & Z. K. Zhou comb. nov. found in Liuqu, southern Tibet and middle Miocene Christella sp. recovered from the Jinggu Basin in western Yunnan. The frond fossils from both sites share key morphological characteristics that diagnose these fossils as Christella. After detailed comparisons, we further clarified Christella papilio (C. Hope) Holttum, a species distributed in warm, humid habitats at altitudes no more than 1300?m, as the nearest living relative of C. nervosa. This finding suggested that southern Tibet had not reached its present elevation during the late Paleocene (ca. 56 Ma). We propose that the uplift, accompanied by severe cooling and aridification after the late Paleocene, caused the disappearance of Christella in southern Tibet, whereas paleoenvironmental conditions enabled the genus to survive in Yunnan. Our study provides the first example of distributional constraints of ferns in SW China in response to paleoenvironmental changes in the Qinghai–Tibetan Plateau and nearby areas.

Key words: biodiversity, Cenozoic, Christella, fern, fossil, the Qinghai–Tibetan Plateau