Unravelling the Habenaria repens (Orchidaceae) complex in Brazil: a biosystematic and molecular phylogenetic approach

Habenaria repens (Orchidaceae) represents a species complex distributed from the southern USA to northern Argentina, including several morphological variants, here referred to as morphotypes. To investigate and clarify the morphological and genetic relationships between these morphotypes and resolve the taxonomy of the complex, we applied a biosystematic multi-population approach using molecular phylogenetic, morphometric and population genetics analyses in the group. We sampled 31 (phylogenetic analyses) and 20 (morphometric and microsatellite analyses) populations of Habenaria aranifera and H. repens from Brazil and the USA, including six morphotypes of H. repens. Bayesian and maximum parsimony phylogenetic analyses of nuclear ribosomal (ITS and ETS) and plastid (matK, trnK and rps16-trnK) markers revealed that the complex is polyphyletic, subdivided into three distantly related clades. Population genetic analyses using microsatellites showed a remarkably similar structure to the phylogenetic analyses, but both were different from the morphometric analyses of floral characters, indicating cases of diversification and convergence, probably due to pollination processes. Habenaria aranifera is embedded in a paraphyletic and polymorphic H. repens with a broad geographical distribution and other attributes of an ochlospecies, probably constituting a progenitor-derivative pair. Our results support the recognition of H. aranifera, H. repens and three or four new species.

Automated summary

This study investigated the morphological and genetic relationships within the species complex of Habenaria repens using molecular phylogenetic, morphometric, and population genetics analyses. The results revealed that the complex is polyphyletic, subdivided into three distantly related clades. Population genetic analyses showed a similar structure to the phylogenetic analyses, indicating cases of diversification and convergence, possibly due to pollination processes.