CLEMENT, WENDY L.1*, LAURA L. FORREST2, and SUSAN M. SWENSEN1. 1Ithaca College, Ithaca NY; 2Royal Botanic Garden Edinburgh, Scotland. - Phylogenetic placement of Hillebrandia sandwichensis (Begoniaceae).
Members of the angiosperm family Begoniaceae are spread globally
throughout the tropics and collectively comprise three genera:
Begonia with approximately 1400 species, Symbegonia
with 12 species endemic to New Guinea, and Hillebrandia which
is monotypic and endemic to Hawaii. Begonia is currently
divided among 63 sections with most sections being restricted to
particular continents. Recent phylogenetic reconstructions have
revealed distinct clades of American, Asian, and African species.
Cladistic analyses using sequence data from ITS, rbcL and 18S
indicate that African species of Begonia are basal and that
Hillebrandia is the most ancestral member of the family. A
broader phylogenetic analysis that includes representatives from the
order Cucurbitales (Cucurbitaceae, Datiscaceae, Tetramelaceae,
Begoniaceae, Coriariaceae, and Anisophylleaceae) provides an expanded
view of Hillebrandia’s position within the order. The
ancestral placement of Hillebrandia within Begoniaceae combined
with its endemism to Hawaii poses an interesting biogeographic
question.
Key words: Begoniaceae, Hillebrandia sandwichensis, phylogeny