Molecular phylogenetics and taxonomic revision of H abenaria section P entadactylae ( O rchidaceae, O rchidinae)

As a step towards a revision of the sectional classification of N eotropical species of H abenaria , we focus here on section P entadactylae . In its current delimitation, this is the largest of the 14 New World sections and embraces a group of 34 morphologically heterogeneous species. We expanded the sampling of N eotropical species currently placed in this section and performed B ayesian, maximum likelihood and parsimony analyses using nucleotide sequences from one nuclear (internal transcribed spacer, ITS ) and three plastid ( mat K , trn K intron, rps16 – trn K ) DNA regions. In addition, morphological features of these species were reassessed. Based on our analyses, we propose that H abenaria section P entadactylae should be recircumscribed to include only seven species: H . pentadactyla (the type species of the section), H . dutrae , H . ekmaniana , H . exaltata , H . henscheniana , H . megapotamensis and H . montevidensis . Thirty‐two species previously assigned to the section grouped within unrelated clades and are therefore excluded from the section. There are no unambiguous morphological synapomorphies for the section, but the group can be confidently recircumscribed and identified on the basis of a combination of diagnostic morphological vegetative and floral characters. Morphological floral features in H abenaria montevidensis are distinct from those of other species in the section, probably as a result of a shift to diurnal pollinators. Following a taxonomic revision of the group, H . crassipes is placed under the synonymy of H . exaltata and neotypes are designated for H . crassipes , H . montevidensis and H . recta (=  H . ekmaniana ). All species in the section live in marshes or wet grasslands from northern A rgentina to central B razil; most species are concentrated in southern B razil. Most species are probably rare, and five may be threatened according to the World Conservation Union ( IUCN ) criteria. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society , 2014, 175 , 47–73.