Molecular approaches reveal speciation between red and blue flowered plants in the Mediterranean Lysimachia arvensis and Lysimachia monelli (Primulaceae)
Flower colour constitutes a pivotal evolutionary force in speciation. The Mediterranean Lysimachia arvensis and L. monelli are morphologically variable species having both blue or red flowered plants. Previous studies suggested that L. arvensis plants differing in colour are diverging lineages, but this variation has not been considered in a phylogenetic context. We reconstruct the phylogenetic signal and the ancestral states of flower colour of Mediterranean Lysimachia species by using nuclear (ITS) and three plastid markers. Blue and red specimens are nested in two independent clades in the ITS tree, thus supporting that L. arvensis and L. monelli are polyphyletic, whereas low phylogenetic resolution was found in plastid markers. Blue-flowered L. arvensis is reconstructed sister to L. talaverae in a monophyletic clade sister to the remaining Lysimachia. Red-flowered L. arvensis is reconstructed sister to red-flowered L. monelli in a monophyletic clade sister to blue-flowered L. monelli and L. foemina. Our results suggest that colour lineages in L. arvensis and L. monelli constitute different species, but flower colour did not promote the separation of these lineages. We propose a new name for blue-flowered L. arvensis (L. loeflingii) and a new combination for red-flowered L. monelli (L. collina).