Three lonely Argentines: Toward a new generic delimitation in Polygalaceae

Abstract

Three enigmatic lineages of the Polygalaceae endemic to the semi-arid region of Argentina were sampled within the framework of a molecular phylogenetic study of its genera. The regions nrITS, matK, the trnL intron, the trnL-trnF intergenic spacer, and rbcL were analyzed, and the history of some morphological characters was reconstructed in the family. Results of our phylogenetic analyses and morphological study support the recognition of three monotypic genera historically treated in the genera Bredemeyera and Polygala. A new genus, Rhamphopetalum, and a new combination, R. microphyllum, are proposed together with resurrection of Hualania and Monrosia. The emergence of two species (Bredemeyera colletioides, B. microphylla) as new genera resolves the polyphyletic status of Bredemeyera. Relationships and morphological characters among the genera of Polygalaceae are discussed. Provided here are photographic plates of Hualania colletioides, Monrosia pterolopha, and Rhamphopetalum microphyllum habits, with details of floral structures, a distribution map, typifications, and taxonomic keys for the tribes of Polygalaceae and genera within the tribe Polygaleae.