title: Phylogenetic placement and taxonomy of the genus Hederorkis (Orchidaceae).
abstract: Three plastid regions, matK, rpl32-trnL and rpl16 intron and the ITS1-5.8S-ITS2 nuclear ribosomal DNA were used to demonstrate a phylogenetic placement of the genus Hederorkis (Orchidaceae) for the first time. The taxonomic position of this genus has been unclear thus far. The phylogenetic and morphological relations of Hederorkis to the most closely related genera Sirhookera, Adrorhizon, Bromheadia and Polystachya are also discussed. A hypothesis concerning an origin and evolution of Hederorkis is proposed. Hederorkis is an epiphytic two-leaved orchid genus with lateral inflorescence, non-resupinate flowers, elongate gynostemium and rudimentary column foot. It is native to the Indian Ocean Islands. Two species of Hederorkis are recognized worldwide, H. scandens endemic to Mauritius and Réunion and H. seychellensis endemic to Seychelles. For each of the species treated a full synonymy, detailed description and illustration are included. The distribution map and dichotomous keys to the species have also been provided.
authors.affiliation: Department of Plant Taxonomy and Nature Conservation, The University of Gdansk, Wita Stwosza 59, PL-80-308, Gdańsk, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Mytnik-Ejsmont
authors.affiliation: Department of Plant Taxonomy and Nature Conservation, The University of Gdansk, Wita Stwosza 59, PL-80-308, Gdańsk, Poland.
authors.forename: Dariusz L
authors.initials: DL
authors.lastname: Szlachetko
authors.affiliation: Department of Plant Taxonomy and Nature Conservation, The University of Gdansk, Wita Stwosza 59, PL-80-308, Gdańsk, Poland.
authors.forename: Przemysław
authors.initials: P
authors.lastname: Baranow
authors.affiliation: Cousine Island, Conservation Department, Seychelles.
authors.forename: Kevin
authors.initials: K
authors.lastname: Jolliffe
authors.affiliation: Department of Molecular Evolution, The University of Gdansk, Wita Stwosza 59, PL-80-308, Gdańsk, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Górniak
mesh_terms: D018744:DNA, Plant / Q000235:genetics; D008969:Molecular Sequence Data; D029595:Orchidaceae / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics; D010802:Phylogeny; D012750:Seychelles
chemical_list: D018744:DNA, Plant