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