Monopyle Moritz ex Benth. is a genus of herbs or suffrutescent herbs distributed from Guatemala southward into northern South America. This assemblage of plants is characterized by the presence of anisophyllous leaves, uncinate trichomes, and campanulate flowers. The genus was last revised in 1945 by Conrad Morton. Since that time, few additional taxa have been recognized. It was comprised of 22 described species in 2011, with two infraspecific taxa. Also, there has been limited sampling of this genus for phylogenetic studies to assess the evolution of the genus. There were two primary foci of this research, a morphological characterization of the species within Monopyle and molecular analyses of the species within Monopyle and other closely related genera. A detailed morphological analysis was performed to determine the morphological differentiation between taxa. This analysis also confirmed which diagnostic characters identified in previous studies were valid and useful. This analysis was accomplished by comparing traits of over 3,000 herbarium specimens. This analysis revealed that Monopyle is the most taxon rich genus in Gloxinieae, with nearly 100 species and a single infraspecific taxon. To ascertain the evolutionary relatedness of species within the genus and to other closely related genera, phylogenetic analyses of two genetic markers was utilized. The nuclear marker (GFLO) and a chloroplast marker (trnT-trnL) were used in the study to assess potential hybridization and polyploidy events. The phylogenetic analysis showed 4 that Monopyle is a monophyletic lineage and that it likely hybridized in the past with a Diastema-like lineage and an ancestor of Phinaea. These analyses indicate the need to recognize four new genera in Gloxinieae. The nuclear phylogeny also suggested that multiple polyploidy or duplication events have occurred recently in the Gloxinieae. Further study in the tribe and genus should focus on ascertaining the number of duplication events and the amount of hybridization to provide a more clear picture of the evolution of these taxa.
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