Evolution of Suessenguthia (Acanthaceae) inferred from morphology, AFLP data, and ITS rDNA sequences

The phylogeny and evolution of Suessenguthia (Acanthaceae), a genus of six species from the Andean foothills and adjacent Amazonia in Bolivia, Peru and western Brazil, are discussed based on morphological and molecular (amplified fragment length polymorphism, ITS rDNA) data. Suessenguthia forms a paraphyletic group at the base of the larger genus Sanchezia. The non-overlapping geographical distribution of closely related species suggests that parapatric or allopatric speciation is the major mode in the genus. A major evolutionary tendency promoting diversification of the group presumably was a change from bee- to hummingbird pollination, resulting in a successive adaptation of flower morphology and inflorescence structure.