Molecular phylogenetics and taxonomic revision ofHabenariasectionPentadactylae(Orchidaceae, Orchidinae)

Abstract

As a step towards a revision of the sectional classification of Neotropical species of Habenaria, we focus here on section Pentadactylae. 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 Neotropical species currently placed in this section and performed Bayesian, maximum likelihood and parsimony analyses using nucleotide sequences from one nuclear (internal transcribed spacer, ITS) and three plastid (matK, trnK intron, rps16-trnK) DNA regions. In addition, morphological features of these species were reassessed. Based on our analyses, we propose that Habenaria section Pentadactylae 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 Habenaria 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 Argentina to central Brazil; most species are concentrated in southern Brazil. Most species are probably rare, and five may be threatened according to the World Conservation Union (IUCN) criteria.

Descriptions and phylogenetic relationships of four new species and a new name of Habenaria (Orchidaceae) from the cerrado and campos rupestres of Brazil

“…The latter was used as the functional outgroup. This dataset is basically the same used by Pedron et al (2014) to infer phylogenetic relationships in Habenaria sect. Pentadactylae Kraenzl., although it also includes three of the new species described here (H. brachydactyla, H. irwiniana, and H. pansarinii) as well as H. bicornis Lindl.…”

“…matK dataset used by us to infer phylogenetic relationships of New World Habenaria , it includes a selected sample of species encompassing all major subclades of Neotropical Habenaria and 2.6 times more characters. Voucher information, geographic origins, and GenBank accession numbers can be found in Pedron et al (2014); information concerning the newly sequenced accessions is provided in Table 1.…”

“…The plastid DNA regions included the complete sequences of the matK gene, part of the upstream and the complete downstream contiguous trnK intron, and the rps16-trnK intergenic spacer. DNA extraction, amplification, and sequencing were carried out as described by Pedron et al (2014). Bidirectional sequence reads were obtained for all of the DNA regions, and the resulting sequences were edited and assembled using Staden Package software (Bonfield et al 1995).…”

“…Because no strongly supported conflicting topologies were detected in our previous analyses with similar datasets (Pedron et al 2014), only searches performed with the combined matrix are presented and discussed. Phylogenetic analyses using MP were performed using PAUP* version 4 (Swofford 2002) with Fitch parsimony (equal weights, unordered characters;Fitch 1971) as the optimality criterion.…”

“…An evolutionary model for each DNA region was selected using the Akaike information criterion (AIC) in MrModeltest 2 (Nylander 2004). The selected models were the same as described in Pedron et al (2014). The unlink command was used to unlink parameters among each partition.…”