Viola kauaensis var. hosakae (Violaceae), a new variety of endemic Hawaiian violet

Abstract

The Hawaiian endemic Viola kauaensis A. Gray has a broad distribution in bogs of Kaua`i and a limited distribution on mesic ridges in the Ko`olau Mountains of O`ahu. Based on differences in scale, the O`ahu populations of V. kauaensis had previously been described as a distinct taxon. The taxonomic status of the O`ahu populations was reevaluated through a morphometric analysis of all varieties of V. kauaensis and the morphologically similar V. vanroyenii. Morphological features of historic and freshly collected specimens of all varieties of V. kauaensis were analyzed with a principal components analysis. Populations from O`ahu represent a distinct cluster that slightly overlaps with V. kauaensis var. kauaensis. Lamina width, apex angle, and base angles contribute to the separation of the O`ahu populations from other varieties of V. kauaensis. Due to differences in scale, the O`ahu populations are described as Viola kauaensis var. hosakae, a new critically endangered taxon.