Revision of Geranium sections Azorelloida, Neoandina, and Paramensia (Geraniaceae)

The sections Azorelloida, Neoandina, and Paramensia of Geranium, all of them from the Andes, are taxonomically revised. Fruits with the ‘seed ejection-type’ dispersal have been found in all species, which allows classifying them within subg. Geranium. The sections Azorelloida and Paramensia consist of one and two species respectively, while section Neoandina comprises 24 taxa. Prior to this revision, the stemless species of Geranium from the Andes have been considered to belong to sect. Andina. Geranium sessiliflorum (type of Geranium sect. Andina), however, should be included in sect. Chilensia. Therefore, recently a new sect. Neoandina has been described to include most of the sect. Andina species (Aedo, 2000). Diagnostic morphological features are analysed and compared within and between the sections. The parsimony analysis suggested an early separation of sect. Paramensia from the rest of the ingroup constituted by the sections Azorelloida and Neoandina. These sections would later on have become separated into two groups: one with paramo species, and the other with more xerophilous, cold-resistant puna species. The biogeographic analyses using Fitch parsimony, dispersal-vicariance optimisation, and Bremer analysis support a paramo origin for the entire group in the North Andes, followed by a colonisation of southernmost regions (puna) and vicariance. A key, species descriptions, a complete list of synonymy, a list of specimens examined, and distribution maps are provided. Most species are illustrated for the first time. Fifteen lectotypes and one neotype are designated.