Phylogeny and Classification of Voyria (saprophytic Gentianaceae)

Abstract

A cladistic analysis of the saprophytic genus Voyria Aubl. (Gentianaceae) was performed to evaluate infrageneric classification, character evolution, and biogeography. A matrix of 19 species of Voyria and 39 morphological characters yielded three most-parsimonious trees, one of which was identical to their strict consensus. The major division within Voyria based on character support is also the rooting point suggested by a larger cladistic analysis of gentians. We have chosen to treat these distinct clades as two new subgenera, Voyria subgen. Voyria Aubl. and Voyria subgen. Leiphaimos (Schltdl. & Cham.) V. A. Albert & L. Struwe, stat. nov. Concerning character evolution, Voyria subgen. Voyria (5 spp.) is the most similar to other Gentianaceae. The saprophytic condition is more advanced in Voyria subgen. Leiphaimos (14 spp.), in which stomates and a continuous vascular cylinder are lacking. Within subgen. Leiphaimos, trends toward extreme vascular reduction and wind-mediated seed dispersal are evident. The extensive character evolution observed within Voyria as a whole may correlate with relaxation of autotrophic structural constraints. Optimization of an area of distribution character on the cladograms obtained suggests that Guayana (and therefore northern South America) may represent the most ancestral area for extant Voyria.