Genetic Variation and Differentiation of <i>Himantoglossum</i> s.s. in Greece

The taxonomic identification of plant species is traditionally based on morphological traits, the use of which may create difficulties in cases of close-related species showing great morphological variability. In such cases, the use of DNA markers for species identification and delimitation can be of great help. <i>Himantoglossum</i> W.D.J.Koch (<i>Orchidaceae</i>) is a genus with notable morphological variability, comprising the clade <i>hircinum-caprinum</i> (<i>Himantoglossum</i> s.s.) with nine taxa, from which <i>H. jankae</i>, <i>H. hircinum</i>, <i>H. montis-tauri</i>, <i>H. caprinum</i> and <i>H. samariense</i> have being reported in Greece. However, a previous morphological study of <i>Himantoglossum</i> s.s. from all over Greece could not verify the presence of these reported species, but of only one highly diverse taxon throughout the country. Here, we studied the genetic variation and differentiation of <i>Himantoglossum</i> s.s. populations from the entire distribution of the genus in Greece employing ISSR markers, to further elucidate the taxonomic status of <i>Himantoglossum</i> s.s. in Greece. High genetic variation was revealed, both in the populations of the “core” distribution and in the peripheral/marginal ones, pointing to their evolutionary potential. This variation is mainly attributed to differences within the populations and, to a lesser extent, among them. No differentiation of the populations proposed to belong to a different taxon was found and no species-specific markers were identified that may discriminate the above populations from the rest. In addition, two cpDNA and one nDNA fragments (<i>acc</i>D, <i>psb</i>A-<i>trn</i>H and ITS2, respectively) were sequenced in a number of individuals representative of the whole dataset. All three fragments were conserved, showing restricted polymorphism and having no correlation to the populations or to the taxa of <i>Himantoglossum</i> s.s. in Greece. Overall, the high genetic variation of the populations of <i>Himantoglossum</i> s.s. in Greece, especially of the peripheral/marginal ones, is a valuable asset towards their conservation.