Accurate taxonomy and species boundaries are of great importance in biodiversity hotspots with high species endemicity like the Caribbean. Indeed, inaccurate species delimitations can affect biodiversity estimates and influence the decisions taken on conservation issues. The genera Gesneria and Rhytidophyllum constitute the main representatives of the Caribbean Gesneriaceae and contain a few complexes with unclear taxonomic boundaries that are characterized by a confusing history of taxonomic changes and by the presence of several recognized varieties and subspecies. Gesneria viridiflora is a good example of such a complex. Four geographically isolated subspecies are recognized that have similar but variable vegetative and reproductive characters, and numerous taxonomic changes have been suggested in this group over the years. In this study, we used multivariate approaches to delimit distinct clusters of individuals using morphological (qualitative and quantitative characters) and molecular data from four nuclear markers. These groups are then tested using a Bayesian coalescent species delimitation approach and compared using multivariate analyses of bioclimatic variables obtained from occurrence data. The results suggest the presence of four distinct species in this complex according to the unified species concept: G. quisqueyana, G. sintenisii, G. sylvicola and G. viridiflora . We also maintain G. viridiflora subsp. acrochordonanthe that does not fulfill our criteria for a species but that shows morphological variation associated to a specific geographical area. A distribution map, an identification key to the species, and a taxonomic treatment are provided. The new taxonomy proposed in this study shows an unsuspected species endemism in some regions of the Caribbean and underlines the importance of investigating species delimitation in diversified groups containing taxonomically complex taxa with poorly defined boundaries.
Species delimitation in the Caribbean Gesneria viridiflora complex (Gesneriaceae) reveals unsuspected endemism