Dactylorhiza maculata species aggregate (Orchidaceae: Orchidoideae) in Murmansk Region (North European Russia): morphological delimitation of plants with different ploidy level

As a result of studies of the genus Dactylorhiza undertaken by Alexey B. Shipunov, numerous "northern tetraploids" – plants combining the genomes of diploid D. fuchsii and tetraploid D. maculata s.str., were found among the material from North European Russia. However, it remained unclear whether non-hybrid D. fuchsii was represented in the northern part of the genus' range, as well as what the morphological distinctive features of plants with different ploidy levels were. Cariology and morphometric studies on material from the Murmansk Region showed that both diploid (2n=40) and tetraploid (2n=80) plants occur here, and plants with different ploidy, as a rule, do not occur together. Diploids were associated with D. fuchsii, but their high morphological similarity with tetraploids was noted, apparently due to the smoothing of morphological differences in "northern tetraploids", as well as due to the weak ecological divergence of species of the genus Dactylorhiza in the northern part of their range. The best distinguishing features of plants with different ploidy, established by methods of mathematical statistics, are considered in detail in the paper.