A New Species of Monrosia (Polygalaceae) from Argentina, and Revision of this Genus Endemic to the Southern Andes

The recently resurrected monotypic genus Monrosia (Polygalaceae) is endemic to the Argentinian provinces of Catamarca to San Juan in the southern Andes. We here describe and illustrate Monrosia sanjuanensis, a new species endemic to the Province of San Juan and the second species of the genus, and revise the genus. Monrosia and its two species are described and analysed in a phylogenetic context, using nuclear and chloroplast DNA sequences. A distribution map, illustration, photos of the morphological structures of the two species, and taxonomic key are provided. We designate a lectotype for the name M. pterolopha.