Plant Diversity ›› 2021, Vol. 43 ›› Issue (05): 409-419.DOI: 10.1016/j.pld.2021.01.002

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Morphological and genomic evidence for a new species of Corallorhiza (Orchidaceae: Epidendroideae) from SW China

Jia-Xin Yanga,b,c, Shuai Penga,b,c, Jun-Jie Wanga,b,c, Shi-Xiong Dinga,b,d, Yan Wanga,b,c, Jing Tiana,b, Han Yange, Guang-Wan Hua,b, Qing-Feng Wanga,b   

  1. a CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China;
    b Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan, 430074, China;
    c University of Chinese Academy of Sciences, Beijing, 100049, China;
    d Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Utilization, Forestry College, Jiangxi Agricultural University, Nanchang, 330045, China;
    e Administration of Siguniang Mountains National Nature Reserve, Xiaojin, 624206, China
  • Received:2020-11-11 Revised:2021-01-02 Online:2021-10-25 Published:2021-11-18
  • Contact: Guang-Wan Hu
  • Supported by:
    The authors are grateful to the Project of Orchid Biodiversity Survey of China from National Forestry and Grassland Administration. We also thank professor Xiao-Hua Jin for confirming the identification and encouraging us to publish this new species, and staffs from Siguniangshan National Nature Reserves for their help during the field work. We acknowledge the National Wild Plant Germplasm Resource Center for all kinds of support. This work was supported by the grants from the Second Tibetan Plateau Scientific Expedition and Research (STEP) program (2019QZKK0502), the National Natural Science Foundation of China (31970211).

Abstract: Corallorhiza sinensis, a new species of mycoheterotrophic orchid from western Sichuan, China, is described and illustrated based on molecular and morphological evidence. It is morphologically similar to Corallorhiza trifida, but can be distinguished by bigger flowers, both sepals and petals with 3 veins, and longer lateral lobes of lip. To distinguish the new Corallorhiza species and explore its phylogenetic position within subtribe Calypsoinae, this study employed sequences of the nuclear ribosomal DNA (nrDNA) and whole plastome assembled from the genome skimming approach. The plastome is 148,124 bp in length, including a pair of inverted repeats (IRs) of 26,165 bp, a large single-copy region (LSC) of 82,207 bp, and a small single-copy region (SSC) of 13,587 bp. Further, phylogenetic analyses were performed using nrDNA sequence and 79 coding sequences (CDSs) from 26 complete plastomes of subtribe Calypsoinae. The phylogenetic tree based on nrDNA sequence suggested that Corallorhiza is a monophyletic group, and strongly support C. sinensis as sister to the rest species of Corallorhiza. The plastid tree showed that 10 Corallorhiza species grouped into two clades and C. sinensis is most closely related to the North American C. striata and C. bentleyi instead of Oreorchis foliosa and O. angustata in the same clade. The plastid tree and nrDNA tree indicate Oreorchis is a paraphyletic. Although the topological conflicts are displayed between plastome and nrDNA phylogenies of C. sinensis, it is still the most closely related to Corallorhiza. Comparative analysis showed that C. sinensis populations are characteristic of the intermediate morphological traits between Corallorhiza and Oreorchis. The finding of this new species from China shed new light on the phylogeny of Oreorchis and Corallorhiza.

Key words: Corallorhiza sinensis, Oreorchis, Sichuan province, Plastome, Phylogeny