Pseudognaphalium (Asteraceae, Gnaphalieae) diversity in New Zealand revealed by DNA sequences with notes on the phylogenetic relationships of Hawaiian Islands plants referred to Pseudognaphalium sandwicensium

Pseudognaphalium luteoalbum (L.) Hilliard & Burtt is a morphologically variable cosmopolitan species allied to a number of geographically restricted taxa with a confusing taxonomic history. The relationships and circumscription of these taxa have never been the subject of a global study. We subjected plastid genome and nuclear-ribosomal DNA sequences from New Zealand samples of P. luteoalbum and the threatened endemic P. ephemerum de Lange to phylogenetic analyses along with sequences from elsewhere in the world. Our analyses suggest that two lineages of the genus are present in New Zealand. One was collected from urban and peri-urban locations and we propose it is naturalised to New Zealand. The other was collected from peri-urban and relatively unmodified locations and we propose that it is indigenous and provide the new combination P. lanatum (G.Forst) Smissen, Breitw. & de Lange for the indigenous lineage at species rank. Pseudognaphalium ephemerum sequences were part of the lineage putatively indigenous to New Zealand but their sequences were not distinguishable from some others of this lineage in our analyses. Hawaiian Islands samples attributed to the four varieties of P. sandwicensium (Gaudich) Anderb. may all belong to different species. Sequences of two P. sandwicensium plants match those of the lineage putatively naturalised in New Zealand. Those of P. sandwicensium var. kilaueanum (O.Deg. & Sherff) W.L.Wagner are most similar to those of the putatively indigenous New Zealand lineage. Another group of Hawaiian Islands plants, including one of P. sandwicensium var. molokaiense (O.Deg. & Sherff) W.L.Wagner from west Maui, are more closely related to the Asiatic species P. affine (D.Don) Anderb. than to the other Hawaiian Islands lineages or either New Zealand lineage. The affinities of P. sandwicensium var. hawaiiense (O.Deg. & Sherff) W.L.Wagner lie with native North American Pseudognaphalium species.