Morphological variation of Gentiana section Chondrophyllae in South America and taxonomic implications

Gentiana species and varieties in the Andes of South America are morphologically weakly differentiated and geographical distribution ranges are not known. Here, we recorded 20 morphological characters for 135 individuals of Gentiana from within and outside South America, and observed four additional characters from a large collection of georeferenced flower photographs. To assess geographical patterns and draw taxonomic consequences, the characters were evaluated individually using box plots and histograms, and together using multivariate ordination plots. Our data support the recognition of two species: one in northern South America, G. sedifolia Kunth, and one in southern South America, G. gayi Griseb., which seem to intergrade in southern Bolivia approximately where wet puna converges into dry puna vegetation. Unusually small individuals of the southern lineage occur in the very South (>45°S). We treat them as G. gayi subsp. magellanica (Kusn.) S.Pfanzelt et K.B.Hagen comb. et stat. nov. We found no support for other previously described species or varieties and if they exist they will be of local distribution only. The respective lectotypifications are made. In our preferred scenario, G. sedifolia and G. gayi have colonized South America independently from the northern hemisphere, although this was not unequivocal and both species are closely related.