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

Phy1ogenetic re1ationships Of Chionopost-pleistocene colonisation ofnewly created habiand the genus Chionohebe may be paraphyletic by parahebe and Chionohebe are two related genera Parahebe vandewateri have New Zea1and ancestry and have subsequent1y dispersed to Austra1ia and (196 1) placed the New Zealand species in three informal groupS. Group A includes p , decora, p . lyallii, P. catarractae, and P. hookeriana; Group B includes P. linifolia, P. planopetiolata, P. trifida, P. birleyi, P. spathulata, and P. cheesemanii; and group C consists of P. canescens. Species of Parahebe characteristically are plants of open rocky habitats ranging from the lowlands to alpine, although P. caneScens is restricted to the margins of tarns pools, or lakes that are seasonally dry during summer and flooded or frozen during winter. The genus Chionohebe currently includes six species in New Zealand. Chionohebe ciliolata and C. densifolia are also found in Australia. All six species are restricted to alpine habitats (Van Royen & Ehrendorfer 1970; Van Royen 1972; Briggs & Ehrendorfer 1976,1992; Garnock-Jones 1976a, 1976b; Garnock-Jones & 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.