Phylogenetic Placements of Loxoscaphe thecifera (Aspleniaceae) and Actiniopteris radiata (Pteridaceae) Based on Analysis ofrbcLNucleotide Sequences

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Abstract
Nucleotide sequences of the chloroplast-encoded rbcL gene were determined for Loxoscaphe thecifera and Actiniopteris radiata and used in maximum parsimony cladistic analyses to determine their phylogenetic positions in the context of a broad range of advanced fern taxa. Loxoscaphe nested firmly within the Aspleniaceae, and Actiniopteris was placed with Onychium in the Pteridaceae. To help resolve conflicting contemporary treatments that either subsume Loxoscaphe species within Asplenium or segregate them as an independent genus, the rbcL sequence of L. thecifera was subjected to a more focused analysis involving all rbcL sequences available to represent the taxonomic diversity of Aspleniaceae. Loxoscaphe thecifera was sister to Asplenium griffithianum + prolongatum, robustly and surprisingly nested within the clade of Asplenium species recognized as Asplenium section Thamnopteris, a group accepted by some as the segregate genus Neottopteris. These results indicate that there is presently no phylo...