title: Identification of the relationship between Chinese Adiantum reniforme var. sinense and Canary Adiantum reniforme.
abstract: BACKGROUND
  There are different opinions about the relationship of two disjunctively distributed varieties Adiantum reniforme L. var. sinense Y.X.Lin and Adiantum reniforme L. Adiantum reniforme var. sinense is an endangered fern only distributed in a narrowed region of Chongqing city in China, while Adiantum reniforme var. reniforme just distributed in Canary Islands and Madeira off the north-western African coast. To verify the relationship of these two taxa, relative phylogenetic analyses, karyotype analyses, microscopic spore observations and morphological studies were performed in this study. Besides, divergence time between A. reniforme var. sinense and A. reniforme var. reniforme was estimated using GTR model according to a phylogeny tree constructed with the three cpDNA markers atpA, atpB, and rbcL.
  
  
  RESULTS
  Phylogenetic results and divergence time analyses--all individuals of A. reniforme var. sinense from 4 different populations (representing all biogeographic distributions) were clustered into one clade and all individuals of A. reniforme var. reniforme from 7 different populations (all biogeographic distributions are included) were clustered into another clade. The divergence between A. reniforme var. reniforme and A. reniforme var. sinense was estimated to be 4.94 (2.26-8.66) Myr. Based on karyotype analyses, A. reniforme var. reniforme was deduced to be hexaploidy with 2n = 180, X = 30, while A. reniforme var. sinense was known as tetraploidy. Microscopic spore observations suggested that surface ornamentation of A. reniforme var. reniforme is psilate, but that of A. reniforme var. sinense is rugate. Leaf blades of A. reniforme var. sinense are membranous and reniform and with several obvious concentric rings, and leaves of A. reniforme var. reniforme are pachyphyllous and coriaceous and are much rounder and similar to palm.
  
  
  CONCLUSIONS
  Adiantum reniforme var. sinense is an independent species rather than the variety of Adiantum reniforme var. reniforme. As a result, we approve Adiantum nelumboides X. C. Zhang, nom. & stat. nov. as a legal name instead of the former Adiantum reniforme var. sinense. China was determined to be the most probable evolution centre based on the results of phylogenetic analyses, divergence estimation, relative palaeogeography and palaeoclimate materials.
authors: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. wangaihua@scbg.ac.cn.|University of Chinese Academy of Sciences, Beijing, 100049, China. wangaihua@scbg.ac.cn.
authors: Ai-Hua
authors: AH
authors: Wang
authors: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. sun-ye@scib.ac.cn.
authors: Ye
authors: Y
authors: Sun
authors: Department of Life Sciences, Natural History Museum, London, SW75BD, UK. h.schneider@nhm.ac.uk.
authors: Harald
authors: H
authors: Schneider
authors: College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. zhai-jw@163.com.
authors: Jun-Wen
authors: JW
authors: Zhai
authors: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. liudm@scib.ac.cn.
authors: Dong-Ming
authors: DM
authors: Liu
authors: College of Chinese Traditional Medicine, Guangzhou University of Chinese Medicine, Guangzhou, 510006, China. zhoujins@gzucm.edu.cn.
authors: Jin-Song
authors: JS
authors: Zhou
authors: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. xinfw@scib.ac.cn.
authors: Fu-Wu
authors: FW
authors: Xing
authors: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. h.f.chen@scbg.ac.cn.
authors: Hong-Feng
authors: HF
authors: Chen
authors: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. wangfg@scib.ac.cn.
authors: Fa-Guo
authors: FG
authors: Wang
mesh_terms: D035681:Adiantum / Q000145:classification* / Q000235:genetics; D002681:China; D032461:Chromosomes, Plant; D018744:DNA, Plant / Q000235:genetics; D005819:Genetic Markers; D007621:Karyotyping; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010802:Phylogeny; D013030:Spain
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers
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