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

doi:10.1016/j.pld.2023.07.003

Abstract

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

Xin-Mao Zhou, Li-Bing Zhang. Phylogeny, character evolution, and classification of Selaginellaceae(lycophytes)[J]. Plant Diversity, 2023, 45(06): 630-684.

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