Systematics and biogeography of the neotropical genus paradrymonia and close allies

Abstract

It is widely known that loss of biological diversity at different levels, such as genetic lineages, species, populations, communities and natural habitats, is imminent in many areas on Earth. That loss is exacerbated by the lack of taxonomic knowledge of many groups of organisms. Taxonomic knowledge is necessary to understand the ecology, biogeography and evolutionary history of organisms, as well to accurately implement management plans for the conservation of biodiversity. As with many other neotropical plant genera, <italic> Paradrymonia</italic> Hanst. (Gesneriaceae) was in need of a taxonomic revision. The genus, as traditionally circumscribed, includes a non-monophyletic assemblage of approximately 40 species of terrestrial and facultative epiphytic herbs that inhabit the understory of neotropical forests. The generic circumscription of <italic> Paradrymonia</italic> has been historically confusing and problematic due to the lack of unique diagnostic morphological characters. Molecular data of nuclear ribosomal and plastid DNA were used to reconstruct species relationships within the genus and closely related genera in subtribe Columneinae. <italic> Paradrymonia</italic> as traditionally defined is paraphyletic and includes taxa in three different clades. Phylogenetic results supported the re-circumscription of <italic> Paradrymonia</italic> and the resurrection of two previously recognized genera, <italic> Centrosolenia</italic> and <italic> Trichodrymonia</italic>, in order to accommodate the remaining ex-<italic> Paradrymonia</italic> species. New combinations, synonymies and further nomenclatural recommendations are made. A taxonomic revision of a re-circumscribed <italic> Paradrymonia</italic> is included. The revision includes a dichotomic key and a description for all the eight species. Furthermore, evolution of nine morphological and ecological characters was accessed using ancestral character reconstructions. Most of the characters for different lineages within the <italic> Paradrymonia</italic> alliance were homoplastic, suggesting convergent evolution as adaptation to similar ecological conditions and pollinators. Finally, ecological niche modeling (ENM) is used to assess the influence of Pleistocene climate in the Last Glacial Maximum (LMG; ~21,000 BP) on the current distribution of lowland species. Results are consistent with the existence of Pleistocene forest refugia as "museums" and not as drivers of speciation, which is inconsistent with the Pleistocene Refuge Hypothesis. Finally, descriptions for three species new to science, <italic>Paradrymonia apicaudata</italic>, <italic>P. peltatifolia</italic> and <italic>Nautilocalyx erytranthus</italic>, are provided.