Ordinal phylogeny within the hypnobryalean pleurocarpous mosses inferred from cladistic analyses of three chloroplast DNA sequence data sets: trnL-F,rps4, and rbcL

Classification of families of hypnobryalean mosses into the Hypnales, Leuco dontales, and Hookerials has been taxonomically difficult. Several research ers have sequenced different genes for independent phylogenetic studies of these three pleurocarp groups. Our goal is to summarize available molecular data and compile the largest data set to infer phylogenetic relationships among families as basis for classification at ordinal level. Sequences of r bcL, trnL-F, and rps4 loci for 38 exemplars of most families of Hypnales, L eucodontales, and Hookeriales were analyzed to evaluate whether or not each of the three orders is monophyletic. Cladistic analyses of combined sequen ces, using five taxa in the Bryales as outgroups, reveal a robust clade (de cay > 5) including all hypnobryalean pleurocarps. Within this group, one cl ade (decay = 2) includes only taxa of the Hookeriales, and is sister to a l arge monophyletic group (Hypnales sensu lato) containing all other taxa (de cay = 2) previously in the Leucodontales since major lineages detected do n ot correspond to the traditional Leucodontales or Hypnales. These two order s are not supported by any molecular evidence from rbcL, trnL-F, or rps4, e ither analyzed singly or in different combinations. Additionally, present r esults indicate the need for changes to the current system of three suborde rs of Hypnales and four of the Leucodontales. Phylogenetic reconstructions based on molecular data emphasize the need for a re-examination of the taxo nomic relevance of morphological characters and corroborate previous interp retations of sporophytic morphological similarities as multiple transitions to similar solutions to epiphytism among the pleurocarps.