Phylogenetic analysis of the subtribe Chloraeinae (Orchidaceae): a preliminary approach based on three chloroplast markers

The systematic position and relationships between some South American terrestrial orchids, such as Bipinnula Comm. ex Juss., Chloraea Lindl., Gavilea Poepp. and Geoblasta Barb. Rodr., is unclear. These four genera have been grouped in the subtribe Chloraeinae by several authors. Previous phylogenetic studies of the group have included only a few species of Chloraea and Gavilea and not of Bipinnula or Geoblasta. Relationships among these four genera were explored and the monophyly of the subtribe Chloraeinae and the genera Chloraea and Gavilea were tested in this contribution. Molecular phylogenetic analyses were conducted, using the following three chloroplast markers: the matK-trnK intron, the atpB-rbcL spacer and the rpoC1 gene. Sequences were analysed under maximum parsimony and Bayesian inference. In all the analyses, Bipinnula, Chloraea, Gavilea and Geoblasta were grouped in a clade with high support, where Bipinnula, Geoblasta and Gavilea were nested inside Chloraea. Consequently, Chloraea was paraphyletic, whereas Gavilea turned out to be monophyletic with high values of support. The other species of tribe Cranichideae appeared as sister groups of the Chloraeinae. A more exhaustive taxonomic sampling is needed to resolve the systematic placement of the subtribe Chloraeinae and the internal relationships between the genera and species that form it.