Phylogeny of the fern family Aspleniaceae in Australasia and the south-western Pacific

Abstract

Aspleniaceae is one of the largest fern families. It is species-rich in Australasia and the south-western Pacific (ASWP), where approximately 115 species occur. In the current study, the chloroplast regions rbcL, trnL–trnF and rps4–trnS were sequenced for 100 Aspleniaceae samples from ASWP. These data were combined with published sequences for species from New Zealand and other regions for phylogenetic analyses. Species of Aspleniaceae from ASWP were placed in six of the eight previously identified inter-continental clades. The majority of species from ASWP were placed in two of these clades, with the remaining four clades each being represented by three or fewer species. Strong biogeographic affinities with South-east Asia were observed and immigration, rather than local radiations of endemic taxa, appears to have made a more important contribution to patterns of diversity in ASWP. This study supports the current taxonomic practice of recognising two genera, Asplenium L. and Hymenasplenium Hayata, in Aspleniaceae, and identifies future taxonomic work required for the family in this region, including potential synonymising of species, and revision of species complexes or widespread species that are demonstrably non-monophyletic.