Patterns of diversification in Chionohebe and Parahebe (Scrophulariaceae) inferred from ITS sequences

Abstract

Phylogenetic relationships of Chionohebe and Parahebe were inferred from analysis of ITS sequences. The results suggest that the genus Parahebe is polyphyletic as currently circumscribed, and the genus Chionohebe may be paraphyletic by exclusion of some of the alpine Parahebe. Parahebe lithophila emerges with the Australian endemics Derwentia and Hebe formosa. The alpine species of Parahebe emerge with Chionohebe, Hebe cheesemanii, and H. cupressoides. Parahebe Groups A and B of Ashwin emerge with Hebe and Heliohebe. The origin of the New Zealand taxa is equivocal. Chionohebe densifolia, C. ciliolata, and Parahebe vandewateri have New Zealand ancestry and have subsequently dispersed to Australia and New Guinea. The mountains of New Zealand are an important centre of diversification, and it appears that evolution in the group has been rapid. Autogamy has independently evolved in at least two lineages and may be an adaptation to alpine environments.