Plant Diversity ›› 2023, Vol. 45 ›› Issue (06): 630-684.DOI: 10.1016/j.pld.2023.07.003

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Phylogeny, character evolution, and classification of Selaginellaceae(lycophytes)

Xin-Mao Zhoua, Li-Bing Zhangb   

  1. a. School of Ecology and Environmental Science, Yunnan University, Kunming 650504, Yunnan, China;
    b. Missouri Botanical Garden, 4344 Shaw Blvd, St. Louis, Missouri 63110, USA; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, Sichuan, China
  • Received:2023-02-23 Revised:2023-07-04 Online:2023-11-25 Published:2023-12-28
  • Contact: Li-Bing Zhang,E-mail:Libing.Zhang@mobot.org
  • Supported by:
    The research was partially supported by the Natural Science Foundation of China (#31900186, #32260050), Yunnan Fundamental Research Projects (Grant NO. 202301BF07001-016), and the Glory Light International Fellowship for Chinese Botanists at Missouri Botanical Garden (MO) to X.M. Zhou. We thank Arthur Haines, Michael Hassler, Petra Korall, Carl Rothfels, Alan Smith, and Alan Weakley for helpful email discussion in Feb. 2021, Carl Rothfels, Timothée Le Péchon and other collaborators for sharing materials for our earlier studies, Atsushi Ebihara and Noriaki Murakami for sharing specimen images, and Jing Zhao, Jian-Jun Yang, Shao-Li Fang, and Yu-Xin Li for helping with the figures, Robbin Moran and the owner of plants-of-styria.uni-graz.at/images/selaginella-selaginoides.html for allowing us to use their online images, and Alan Weakley and three anonymous reviewers for helpful comments.

Abstract: Selaginella is the largest and most taxonomically complex genus in lycophytes. The fact that over 750 species are currently treated in a single genus makes Selaginellales/Selaginellaceae unique in pteridophytes. Here we assembled a dataset of six existing and newly sampled plastid and nuclear loci with a total of 684 accessions (74% increase of the earlier largest sampling) representing ca. 300 species to infer a new phylogeny. The evolution of 10 morphological characters is studied in the new phylogenetic context. Our major results include: (1) the nuclear and plastid phylogenies are congruent with each other and combined analysis well resolved and strongly supported the relationships of all but two major clades; (2) the Sinensis group is resolved as sister to S. subg. Pulviniella with strong support in two of the three analyses; (3) most morphological characters are highly homoplasious but some characters alone or combinations of characters well define the major clades in the family; and (4) an infrafamilial classification of Selaginellaceae is proposed and the currently defined Selaginella s.l. is split into seven subfamilies (corresponding to the current six subgenera + the Sinensis group) and 19 genera (the major diagnosable clades) with nine new species-poor genera. We support the conservation of Selaginella with a new type, S. flabellata, to minimize nomenclatural instability. We provide a key to subfamilies and genera, images illustrating their morphology, their morphological and geographical synopses, a list of constituent species, and necessary new combinations. This new classification will hopefully facilitate communication, promote further studies, and help conservation.

Key words: Generic classification, Homoplasy, Lycophyte phylogeny, Megaspore types, Microspores, Nuclear 18S and 26S genes