Taxonomic revision of Australasian snow hebes (Veronica, Plantaginaceae)

Abstract

The snow hebes, formerly comprising the genus Chionohebe, are here included within Veronica (Plantaginaceae). The five species (including two subspecies) of snow hebes recognised here are cushions or subshrubs that occur exclusively in high-elevation habitats of Australia and the South Island of New Zealand. Species delimitation among the cushion snow hebes is very difficult because of the reduced pulvinate habit, solitary flowers and few gross-morphological characters useful for identification. To address species limits, investigate intraspecific patterns and revise the taxonomy of the snow hebes, morphological analyses were conducted and the results compared with previously published molecular phylogenetic data. Ordination and clustering analyses of morphological data showed some taxonomic structuring; however, species clusters were not widely separated from one another. Morphological and amplified fragment length polymorphism (AFLP) data show that the cushion species are clearly distinguished from the subshrub species, V. densifolia (F.Muell.) F.Muell. Among the four cushion species (V. chionohebe Garn.-Jones, V. ciliolata (Hook.f.) Cheeseman, V. pulvinaris (Hook.f.) Cheeseman, V. thomsonii (Buchanan) Cheeseman), the distribution of leaf trichomes is important for species identification, particularly when used in conjunction with ovary vestiture, capsule size, and/or seed size. One new combination V. ciliolata subsp. fiordensis (Ashwin) Meudt is proposed, and V. uniflora Kirk is treated as a naturally occurring hybrid V. × uniflora (V. densifolia × V. thomsonii). Complete synonymies, descriptions, illustrations and range maps are provided for each species, as well as a key to all species and a discussion of putative hybrids.