Molecular support for Pleistocene persistence of the continental Antarctic moss Bryum argenteum

We examined sequence variation of ITS and phy 2 for Bryum argenteum from Antarctica, sub-Antarctic, New Zealand and Australia to understand better taxonomic delimitations and resolve relationships between these geographic regions. Bryum argenteum has been recorded as two species, B. argenteum and B. subrotundifolium , in all four regions with the latter now referred to as B. argenteum var. muticum . We found disagreement between taxon delimitations (based on morphology) and molecular markers. All continental Antarctic specimens consistently formed a monophyletic sister group that consisted of both morphologically identified B. argenteum varieties, separate to all non-Antarctic specimens (also consisting of both varieties). We suggest, contrary to previous records, that all continental Antarctic (Victoria Land) populations are referable to B. argenteum var. muticum , while sub-Antarctic, Australian and New Zealand populations included here are B. argenteum var. argenteum . Additionally, since there was less genetic diversity within Victoria Land, Antarctica, than observed between non-Antarctic samples, we suggest that this is, in part, due to a potentially lower rate of DNA substitution and isolation in northern and southern refugia within Victoria Land since the Pleistocene.