Chloroplast phylogenies of Australasian Gleichenia ferns (Gleicheniaceae) reveal incongruence with current taxonomy, and frequent long-distance dispersal

Gleichenia (Gleicheniaceae) is a genus of distinctive branching ferns well represented in Australasia (Australia, New Caledonia, and New Zealand) where seven of the total eleven species occur. Published chloroplast phylogenies have shown that G. dicarpa is polyphyletic in New Zealand, and that one species from Madagascar and Réunion previously included in Gleichenia represented a separate newly-recognised genus, Rouxopteris . Here, chloroplast rbc L, trn L- trn F and combined trn L- trn F and rps 4- trn S phylogenies are produced for all Australasian species. Australasian species formed a clade sister to the type of Gleichenia , G. polypodioides , confirming their placement in Gleichenia . Gleichenia dicarpa occurred in three major clades, which also contained other species or undescribed forms. The three separate lineages of G. dicarpa were morphologically distinct from these other species or forms; however, the three separate chloroplast lineages of G. dicarpa are difficult to morphologically distinguish from each other. Further study is required to elucidate whether the polyphyly of G. dicarpa could be due to unrecognised cryptic species, hybridisation, or incomplete lineage sorting. Low rbc L variation between all Australasian species suggests a radiation in the last five million years and at least six long-distance dispersal events in Australasia are inferred, comprising five between Australia and New Zealand, and one between Australia and New Caledonia.