Many morphologically defined bryophyte species show intercontinental disjunctions, a pattern rare among vascular plants. Morphologically similar forms in geographically disparate bryophyte populations may also be genetically similar, as a result of either limited evolutionary potential or very effective long-distance dispersal. Alternatively, disjunct populations of bryophytes may be genetically differentiated, but morphology may be a poor indicator of molecular evolution. I employed phylogenetic analyses, in conjunction with morphological studies, to evaluate these two hypotheses in the case of Pyrrhobryum mnioides, a moss common in moist temperate forests in Southeastern Australia, Tasmania, New Zealand, Patagonia and Andean South America. DNA sequence data from the nuclear (ITS and 26S) and chloroplast (trnL and rps4) genomes indicate that Australasian and American populations of P. mnioides are reciprocally monophyletic. The results show evidence of neither intercontinental gene flow nor depressed levels of molecular evolution. The morphological analyses support the assertion of Fife (1995) that populations from the two continental regions are subtly different.

Key words: Pyrrhobryum mnioides , biogeography, bryophyte disjunction, infraspecific phylogeny