J Syst Evol ›› 2014, Vol. 52 ›› Issue (4): 450-457.DOI: 10.1111/jse.12075

• Research Articles • Previous Articles     Next Articles

Rediscovery of Cystoathyrium chinense Ching (Cystopteridaceae): phylogenetic placement of the critically endangered fern species endemic to China

1,2Ran WEI 1Xian-Chun ZHANG*   

  1. 1(State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China)
    2(University of Chinese Academy of Sciences, Beijing 100049, China)
  • Received:2013-10-03 Published:2014-07-10

Abstract: Cystoathyrium chinense Ching, the sole representative of Cystoathyrium, is a critically endangered species endemic to China with no more than 40 extant individuals. Until now, its systematic position and relationships among leptosporangiate ferns remained unknown. The present study assessed the phylogenetic relationships ofCystoathyrium chinense with potential relatives densely sampled using three chloroplast DNA markers (matK, rbcL, and trnG-R intergenic spacer). Our results support the inclusion of Cystoathyrium in Cystopteris. A hybrid origin hypothesis of Cystoathyrium chinense is neither supported nor rejected by the present study. According to our ancestral area reconstruction analysis, the disjunct distribution of Cystoathyrium and its closely related North American taxa may be attributed to the long-distance dispersal by way of Beringia. Consequently, a new combination (Cystopteris chinensis comb. nov.) is made, and the description is supplemented based on our new observations in the field.

Key words: Cystoathyrium, Cystopteridaceae, Cystopteris, eastern Asian-North American disjunction, hybridization hypothesis, molecular phylogeny.