Molecular phylogenetic analyses of the family Mniaceae (including the Pohlioideae and Roellia) were conducted. Three data matricies were constructed: i) a 73-taxon data set of the chloroplast regions trnL-trnF, rps4 and the atpB-rbcL intergenic spacer; ii) a 43-taxon data set representing a subset of data set 1 plus the addition of a further chloroplast region, namely rpl16; and iii) a 19-taxon data set of eight genes: two nuclear ribosomal regions (18S nrDNA and partial 26S nrDNA), one mitochondrial gene (nad5), and five chloroplast regions (trnL-trnF, rps4, psbA, atpB-rbcL, and rpl16). Each data set was analyzed using maximum parsimony, maximum likelihood, and Bayesian phylogenetic inference. The traditional taxa of the Mniaceae form a poorly supported monophyletic group. The genera Mielichhoferia and Schizymenium are derived from taxa in Pohlia sect. Pohlia. The propaguliferous sp. of Pohlia sects. Cacodon and Nyhomiella form a well supported clade to the exclusion of non-propaguliferous species. In addition, Epipterygium is derived from a mniobyoid ancestor. Despite extensive data sampling among diverse taxa of the Mniaceae, a robust phylogenetic hypothesis of the family remains elusive; monophyly of the Pohlioideae cannot be statistically rejected by any dataset. Nevertheless, optimal trees under ML, MP, and Bayesian inferences indicate that the Pohlioideae is probably paraphyletic and that the traditional Mniaceous taxa are derived from a pohlioid ancestor. The lack of robust resolution (due to short internal branches) among the major clades in all genomic partitions is interpreted as indicating a relatively rapid diversification of major lineages within the family. Morphological character reconstructions were performed to identify synapomorphies and provide diagnoses for the major clades. The novel relationships discovered by these analyses will provide a framework for a sub-familial classification of the Mniaceae.

Key words: Bayesian inference, Bryopsida, Mniaceae, Mnium, Pohlia