Abstract
Since the description of the Neotropical genus Vargasiella in 1952, its taxonomic position has remained unclear, mainly due to a lack of sufficient data. In this study, the taxonomic position of Vargasiella was revised based on the outcomes of macro- and micromorphological studies, analyses of selected molecular markers and ecological methods of niche distribution modeling. The phylogenetic relationships were inferred using three DNA markers: matK, trnL-F and ITS sequences. The morphological studies included the analysis of macromorphological features of herbarium specimens as well as micromorphological examination of preserved flowers. The ecological niche modeling was applied to identify the distribution of the suitable niches of the studied taxa. The relationships between Vargasiella and most similar taxa remain unresolved based on the molecular analysis. The outcomes from the morphological studies indicated significant differences between Vargasiella, Warrea and Warreopsis. Moreover, a niche shift in response to changing climate after the last glacial maximum is observed in Vargasiella, while no substantial changes in the occupied habitats were identified in the other related taxa. The clocktree of the Zygopetaleae estimated from the matK gene indicated that the most recent common ancestors of Vargasiella, Warrea and Warreopsis originated in the Miocene, while the divergence time for Vargasiella and Warrea was assessed at approximately 5.4 Ma ago. Vargasiella seems to be an outshoot of the main branch of evolution of the Zygopetaleae. It is noteworthy that the Vargasiella-Warrea dichotomy could have taken place later than the divergence of Warreopsis from the mutual lineage. The molecular analysis and morphological data suggest that Vargasiella and Warrea could have evolved from a common ancestor. Accumulation of morphological differences and acceleration of the evolution of Vargasiella were more intensive than in other Warreinae and this could probably be synchronized with adaptation to different climatic conditions.
Highlights
The concept of the Neotropical orchid genus Vargasiella C.Schweinf. was proposed by Schweinfurth in 1952, along with the description of Vargasiella peruviana C
Branches that collapse in the strict consensus tree are indicated by arrows
The rostellum of Vargasiella is short and broad and its major part becomes transformed into the viscidium and tegula, and when removed with the pollinia drops out as accessories
Summary
The concept of the Neotropical orchid genus Vargasiella C.Schweinf. was proposed by Schweinfurth in 1952, along with the description of Vargasiella peruviana C. The genus comprises only two species with a disjunctive distribution They are terrestrial plants growing in wet, dense, submontane or montane forest, rich in epiphytes and lianas (Fig. 1). Populations of Vargasiella peruviana occasionally form quite large clumps in seasonally inundated meadows next to the forest edge. This plant’s habit is unusual for orchids (Fig. 2a). The sepals and petals of V. peruviana are subsimilar, whereas in V. venezuelana the petals are wider than the sepals The lip in both species is slightly different; in V. peruviana it is ovate-lanceolate to ligulate, undulate along upper margins with a thickened disc (Fig. 2c). The lip of V. venezuelana is elliptic-ovate to almost elliptic-orbicular, undulate above the cordate base, without any thickening
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
