A revision of the genus Gentianella in New Zealand
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Previous work on Gentianella and related genera is reviewed, particularly the taxonomic history of the New Zealand gentians and their generic placement. Phylogenetic analysis of DNA sequences show the New Zealand gentians belong in Gentianella. Thirty species are recognised, including seven species (G. angustifolia, G. calcis, G. decumbens, G. luteoalba, G. impressinenJia, G. scopulorum, and G. stellata) described as new, and one (G. magnifica) raised from varietal status. The identity of G. patula is clarified. The specific status of G. amabilis is affirmed. Thirteen subspecies are recognised, including a new subspecies within G. astonii (subsp. arduana) and four within a new species G. calcis (subsp. calcis, subsp. waipara, subsp. manahune, subsp. taiko). New subspecies are also made in G. corymbifera (subsp. gracilis), G. montana (subsp. ionostigma), and G. chathamica (subsp. nemorosa). G. montana var. stolonifera Cheeseman is the only existing variety that this treatment continues to recognise. Four species recognised by Allan (1961) are reduced to synonymy (G. gracilifolia, G. matthewsii, G. tereticaulis, and G. townsonii). Descriptions and keys are provided for all species and subspecies recognised. Evidence is limited, but Gentianella appears to have arrived in New Zealand from South America once and has probably dispersed once from New Zealand to Australia. The place of the first establishment of Gentianella in New Zealand appears to be in the southern half of the South Island. An initial radiation in the lower South Island was followed by northward range extensions and dispersal events. A second radiation occurred in the Nelson and Marlborough mountains.