Closely related outgroups are optimal for rooting phylogenetic trees; however, such ideal outgroups are not always available. A phylogeny of the marattioid ferns (Marattiaceae), an ancient lineage with no close relatives, was reconstructed using nucleotide sequences of multiple chloroplast regions (rps4 + rps4-trnS spacer, trnS-trnG spacer + trnG intron, rbcL, atpB), from 88 collections, selected to cover the broadest possible range of morphologies and geographic distributions within the extant taxa. Because marattioid ferns are phylogenetically isolated from other lineages, and internal branches are relatively short, rooting was problematic. Root placement was strongly affected by long-branch attraction under maximum parsimony and by model choice under maximum likelihood. A multifaceted approach to rooting was employed to isolate the sources of bias and produce a consensus root position. In a statistical comparison of all possible root positions with three different outgroups, most root positions were not significantly less optimal than the maximum likelihood root position, including the consensus root position. This phylogeny has several important taxonomic implications for marattioid ferns: Marattia in the broad sense is paraphyletic; the Hawaiian endemic Marattia douglasii is most closely related to tropical American taxa; and Angiopteris is monophyletic only if Archangiopteris and Macroglossum are included.

Recent phylogenetic investigations of marattioid ferns (Marattiaceae) have generated a refined understanding of genus-and species-level relationships within the family. A taxonomic revision of marattioid ferns is presented here. This new taxonomy is congruent with the current understanding of the phylogeny of marattioid ferns based on both molecular and morphological data. Marattiaceae is recognized here in the broad and most commonly used sense, encompassing all extant genera. Marattia as traditionally defined is paraphyletic, and is split here into three morphologically distinct and monophyletic genera: Marattia s.str. is restricted to the Neotropics and Hawaii; Eupodium, a distinctive Neotropical genus that has not been recognized by recent authors, is resurrected; and a newly described genus Ptisana comprises the Paleotropical species. Angiopteris is circumscribed broadly to include Archangiopteris, Macroglossum, Protomarattia, and Protangiopteris. Neither Danaea nor Christensenia require changes to their circumscriptions. As Marattia s.l. is undergoing the most drastic change in this taxonomy, species-level detail is given for Marattia s.str. and the segregated genera Eupodium and Ptisana. New combinations are made in Eupodium and Ptisana. Considerable monographic work still remains to be done, and is of particular importance given the threatened status of many presently poorly understood species in this family.

BackgroundTortula ruralis, a widely distributed species in the moss family Pottiaceae, is increasingly used as a model organism for the study of desiccation tolerance and mechanisms of cellular repair. In this paper, we present the chloroplast genome sequence of T. ruralis, only the second published chloroplast genome for a moss, and the first for a vegetatively desiccation-tolerant plant.ResultsThe Tortula chloroplast genome is ~123,500 bp, and differs in a number of ways from that of Physcomitrella patens, the first published moss chloroplast genome. For example, Tortula lacks the ~71 kb inversion found in the large single copy region of the Physcomitrella genome and other members of the Funariales. Also, the Tortula chloroplast genome lacks petN, a gene found in all known land plant plastid genomes. In addition, an unusual case of nucleotide polymorphism was discovered.ConclusionsAlthough the chloroplast genome of Tortula ruralis differs from that of the only other sequenced moss, Physcomitrella patens, we have yet to determine the biological significance of the differences. The polymorphisms we have uncovered in the sequencing of the genome offer a rare possibility (for mosses) of the generation of DNA markers for fine-level phylogenetic studies, or to investigate individual variation within populations.

Abstract:We examined collections of pteridophytes from Moorea and others of the Society Islands, as well as literature relevant to the pteridophytes of Polynesia. This resulted in a list of species known to occur on Moorea, along with a list of species reported for Moorea but lacking voucher specimens, and a list of species perhaps to be found on Moorea based on collections from nearby Tahiti and adjacent islands in the archipelago, at suitable elevations. We include habitat, locality, and appropriate taxonomic commentary for each known species. A new species in the family Psilotaceae, Tmesipteris gracilis Chinnock, is described from the Society and Marquesas Islands. We also include a discussion of pteridophyte collection history on Moorea and biogeographic notes for species on the island.