On the morphological variability and phylogenetic relationships of Crimean and Caucasian members of Lotus section Dorycnium

In the Crimea and the Caucasus, the section Dorycnium (Mill.) D. D. Sokoloff of the genus Lotus L. s. l., attributed by many researchers to the genus Dorycnium Mill., is represented by taxa related to L. graecus L. (= Dorycnium graecum) and L. dorycnium L. (= D. pentaphyllum). To clarify the species composition, diagnostic features, and phylogenetic relationships of the representatives of the section in these two geographical regions, seven Crimean and five Caucasian samples were analyzed. A morphological analysis of the Crimean and Caucasian material was carried out using the methods of one-dimensional and multidimensional (Principal Coordinate Analysis) statistics. Separate molecular phylogenetic analyses by ITS1-5.8S-ITS2 nrDNA and trnL-F cpDNA were performed using a representative set of species of the genus Lotus s. l. The study revealed the presence of two species in the Crimea and the Caucasus: L. graecus and L. herbaceus (Vill.) Jauzein (a representative of the L. dorycnium complex), which differ in many morphological characters (e.g., sizes of flowers, leaves, calyx teeth, and the type of pubescence and the presence/absence of root offspring). Interspecific hybrids were not identified. Within each species, the geographical differentiation between the sequences of both studied markers (ITS and trnL-F) was not observed. The study confirmed that the L. dorycnium complex (including L. herbaceus) from Lotus section Dorycnium according to plastid data is not separated from L. hirsutus, a species from Lotus section Bonjeanea with a wide Mediterranean range that does not reach the Crimea and the Caucasus, as was previously shown by other cpDNA markers.