Hidden in plain sight: a new species of Habenaria (Orchidaceae) from the Espinhaço range in Minas Gerais, Brazil, plus an updated checklist of the genus from Grão Mogol

Background and aims – Habenaria is the largest genus of predominantly terrestrial orchids and the genus with the largest number of species in the family in Brazil. Field expeditions to Grão Mogol, in the northern part of the Espinhaço range of Minas Gerais, Brazil, led to the discovery of a taxon within the Habenaria nuda complex that could not be assigned to any of the known species within the complex. This study aimed to investigate the identity and taxonomic status of this taxon.

Material and methods – We analysed the morphology of the taxon and compared it with herbarium specimens of morphologically similar species. We assessed its phylogenetic relationships using parsimony, maximum likelihood, and Bayesian inference, based on nuclear (ITS and ETS) and plastid (matK - trnK and rps 16 - trnK) DNA sequences. Key results – This taxon belongs to a large clade that mostly comprises species from the Cerrado domain.

It differs from other species in the Habenaria nuda complex in that it has patent lateral sepals, and petal anterior segment and lip lateral segments that are shorter than the petal posterior segment and lip median segment, respectively. It also has small auricles located below the rostellum arms and anther canals. Based on these results, we described it here as a new species, Habenaria adamantina sp. nov.

We present a distribution map, alongside comments on the taxon’s habitat, phenology, and preliminary conservation status, as well as an identification key to differentiate it from other species within the complex. The number of Habenaria species in Grão Mogol has increased from four to 12 species, with the new species being the only one restricted to the region. Conclusion – This study highlights the importance of both continuous and group-specific botanical surveys for documenting biodiversity, particularly for species that are seasonal, inconspicuous, or present in low numbers.