Taxonomic revision of Delphinium (Ranunculaceae) in the south-east of European Russia

<p>Morphological and phylogenetic (nrITS barcode) analyses are conducted to clarify the taxonomic status of 10 <i>Delphinium</i> species (<i>D. cuneatum, D. dyctiocarpum, D. duhmbergii</i>, <i>D. elatum, D. litwinowii</i>, <i>D. pubiflorum</i>, <i>D. puniceum, D. sergii</i>, <i>D. subcuneatum, D. uralense</i>) grown in the south-east of European Russia. The morphometric analysis is carried out with 22 quantitative and 32 qualitative parameters. Based on all parameters, the PCoA supports the differentiation of <i>D. puniceum</i>, <i>D. sergii</i>, <i>D. uralense</i> and <i>D. pubiflorum</i> whereas other studied taxa remain undistinguished. Furthermore, the Random forest analysis and the MrBayes phylogenetic analysis of ITS sequences confirm the species independence of <i>D. puniceum</i> belonging to the <i>Diedropetala</i> section and <i>D. elatum</i>, <i>D. uralense</i>, <i>D. dyctiocarpum</i> and <i>D. pubiflorum</i> belonging to the <i>Delphinastrum</i> section. Finally, recursive partitioning is performed to develop the dichotomous key which can be used to differentiate between <i>Delphinium</i> species in the territory under study. In conclusion, we stress that the definition of species belonging to the <i>Delphinastrum</i> section is hindered by the presence of numerous intermediate or hybrid forms, on the one hand, and the impact of climatic conditions on the display of morphological (and specifically, taxonomically significant) traits, on the other.</p>