Bryological and Lichenological Section/ABLS
Forrest, Laura L. , Crandall-Stotler, Barbara J. .
Molecular phylogeny of the Pallaviciniaceae Mig. (Metzgeriales Schljakov emend. Stotler & Crand.-Stotl., Marchantiophyta).
The Pallaviciniaceae is one of the most diversified families of simple thalloid liverworts, comprising approximately 150 species in 10 genera. The occurrence of one or more ‘vascular’ strands of hydrolyzed cells within the thallus midrib is a unifying character of this group, perhaps being the factor that has allowed the development of a furcated, dendroid habit as found in Symphyogyna, Jensenia, Pallavicinia, and the related taxon Hymenophyton (Hymenophytaceae). In order to elucidate the systematic relationships within this group, and thus gain a better understanding of character evolution, four chloroplast loci were sampled, namely rbcL, psbA, rps4 and trnL. Multiple species or populations, which encompassed much of the morphological diversity of eight genera from Pallaviciniaceae, were included. In addition, both species of Hymenophyton and Phyllothallia nivicola were also included, as previous analyses using five chloroplast, two nuclear and one mitochondrial genes showed these taxa to be very closely related to the family. The analyses were rooted using seven outgroup genera that also showed some affiliation in the wider study. Pallaviciniaceae and Hymenophytaceae resolve as sister taxa, subtended by Phyllothalliaceae. Within Pallaviciniaceae, three major lineages are supported. The first to diverge is a paraphyletic Moerckia, which contains the monotypic genus Hattorianthus. Another lineage contains a paraphyletic Symphyogyna, including the two monotypic genera Xenothallus and Greeneothallus. Sister to this are Pallavicinia, Podomitrium and Jensenia, with Podomitrium contained within a clade of New Zealand species of Pallavicinia. Our results suggest that the dendroid habit has evolved independently in the Hymenophyton, Symphyogyna and Jensenia lineages. The non-monophyly of at least three of the currently accepted genera within the Pallaviciniaceae suggests that a taxonomic revision of the family is needed.
1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA
Presentation Type: Paper
Location: Ballroom 3 (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 4:15 PM