Nothofagus subgenus Brassospora (Nothofagaceae) leaf fossils from New Zealand: a link to Australia and New Guinea?

<em><b>N</b></em><b><em>othofagus palustris</em> sp. nov.</b> is the first record of well-preserved leaves of <em>Nothofagus</em> subgenus <em>Brassospora</em> in New Zealand, and is described from an Oligo–Miocene leaf bed in the Gore Lignite Measures of the South Island. <em>Nothofagus palustris</em> is represented by relatively small and variably toothed leaves with cuticular remains that possess all the characteristic features of the subgenus, including the presence of variably sized stomata that are randomly arranged within areoles, hydathodes along the major veins and ‘bulging cells’ within the areoles on the adaxial side. Phylogenetic assessment shows that the leaves are similar to those of Australian Oligocene and Miocene species and may belong to the same clade of <em>Brassospora</em>. Most notably, these species share the derived feature of abundant leaf wax, a feature that is now only well developed in two New Guinean species. This and other evidence allows the possibility that the ancestor of <em>N</em>.<em> palustris</em> reached New Zealand from Australia. However, it is improbable that <em>N</em>.<em> palustris</em> or a similar species was the common ancestor of the clade of <em>Brassospora</em> that is now confined to New Caledonia. Ecologically, <em>N</em>.<em> palustris</em> is unusual among extant and previously described macrofossil species of <em>Brassospora</em> in being found in a relatively open, swampy habitat.