A Molecular Systematic Study of the Lampranthus Group (Aizoaceae) Based on the Chloroplast TrnL-trnF and Nuclear ITS and 5 S NTS Sequence Data

Abstract The phylogenetic position of the Lampranthus group (Ruschioideae, Aizoaceae), with particular emphasis on the large genus Lampranthus, was studied using DNA sequences from the trnL-trnF region of the chloroplast genome, the nuclear ribosomal internal transcribed spacer (ITS) region and the 5S non-transcribed spacer (NTS). Phylogenies of 59 species in 29 genera of succulent Aizoaceae, including two species from subfamily Mesembryanthemoideae, are presented. Due to an inadequate number of informative sites within the Ruschioideae (31 for trnL-trnF; 49 for ITS), the trnL-trnF and ITS regions are found to be unsuitable for phylogenetic investigations at the specific and generic level. The 5S spacer proves useful at the generic level, but fails to reveal well-supported phylogenies above the generic level. Combined analyses of all three gene regions show that Lampranthus N.E.Br. in its present circumscription is not monophyletic. A “core” of species of Lampranthus is well supported with numerous species of Lampranthus more closely related to other genera. At a higher taxonomic level, the data also do not support a monophyletic Lampranthus group. Circumscription of informal groups within the Ruschioideae, including the Lampranthus group, has mainly been based on the shared presence of a particular type of fruit. Fruits of the Lampranthus group are characterized by long, diverging expanding keels, broad valve wings and the absence of a closing body. The present data implies that this fruit type is homoplasious. Communicating Editor: Alan T. Whittemore