J Syst Evol

• Research Articles •    

A contribution to Gymnosphaera (Cyatheaceae) in mainland Asia: Two new species, reinstatement of Cyathea bonii, and their phylogenetic positions

Shi-Yong Dong1,2*†, Zheng-Yu Zuo3,4,5†, Yong Xiao1, Ling Huang1,4, Van The Pham6,7, Ke Loc Phan8, and Ming Kang1,2   

  1. 1Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
    2Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou 510650, China
    3Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
    4University of Chinese Academy of Sciences, Beijing 10093, China
    5School of Life Sciences, Yunnan University, Kunming 650500, China
    6Environmental Engineering and Management Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam
    7Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Vietnam
    8Faculty of Biology, VNU University of Science, Hanoi, Vietnam

    These authors contributed equally to this work.
  • Received:2020-04-11 Accepted:2020-08-26 Online:2020-08-29

Abstract:

Gymnosphaera represents a minor lineage within the scaly tree‐fern family Cyatheaceae. Tropical and subtropical mainland Asia is a main distribution area of Gymnosphaera. However, the species diversity of Gymnosphaera is currently incompletely known in mainland Asia due to lacking critical revision. Here we present new findings of species diversity and their relationships to mainland Asian Gymnosphaera based on field surveys, the examination of herbarium collections, and phylogenetic analyses of sequences of multiple chloroplast and nuclear regions. Two new species, G. saxicola from southwestern Yunnan and G. bachmaensis from central Vietnam, are established. Traditionally recognized G. podophylla is revealed to be a complex, from which G. bonii is reinstated as a distinct species. Our phylogenetic analyses identified four clades within Gymnosphaera in mainland Asia: G. denticulata clade, G. gigantea clade, G. podophylla clade, and G. salletii clade. The new species G. saxicola, which is special for its saxicolous habitat, was resolved as sister to G. austroyunnanensis in the G. salletii clade. The newly discovered G. bachmaensis, which is characterized specially by the spathulate frond, was positioned in the G. podophylla clade, being sister to G. bonii. The mountainous region from south‐central Vietnam northwards to western Yunnan is a diverse center of Gymnosphaera and more species of this group are probably to be discovered there.

Key words: chloroplast sequence, morphology, nuclear sequence, phylogeny, taxonomy, tree fern