An update of the taxonomic system of Dactylorhiza (Orchidaceae, Orchideae)

An updated taxonomic system of Dactylorhiza is proposed based on earlier classifications and new phylogenetic reconstructions. The main principles of presently adopted classification are discussed. In particular, allotetraploids derived from fuchsii/maculata and incarnata/euxina genomes are placed together in one section, autopolyploids are positioned in the section of their putative parents, and the D. incarnata s.l. in one section together with D. salina s.l. and D. euxina. The arguments for a one-rank system, as opposed to a two-rank classification earlier accepted by many, are advocated. The taxonomic system is brought into line with the presently adopted rules of botanical nomenclature, and all earlier validly (and some invalidly) published names are placed in appropriate places in classification. Seven sections are recognised, one of which, D. sect. Coeloglossum, could be set apart as a separate genus. One new combination, Dactylorhiza sect. Coeloglossum (Hartm.) Efimov, is proposed, and two names, Orchis sect. Klingeanthus and D. subsect. Subsesquipedales, are typified. It is acknowledged that the proposed system has some possible internal nomenclatural instability due to D. sect. Latifoliae, a name of uncertain taxonomic position, which is based on Orchis latifolia L., a confusing rejected name. Approximate species composition of each section is listed, and a key to sections is provided.