Cladistic analysis of the Old World species of Lotus L. (Fabaceae: Loteae)

The diagnostic characters of the genus Lotus L. are a claw with a thickened infolded margin, diadelphous stamens, and a style hardened from the base. This genus contains about 100 species that are distributed throughout the world. To investigate the phylogeny of the Old World species of Lotus, subgenus Edentolotus, sections Krokeria, Xantholotus, and Erythrolotus, a cladistic analysis was performed using 31 morphological characters. To test the phylogenetic relationships among species of Lotus-Edentolotus and Dorycnium, Pedrosia, and Tetragonolobus, these taxa were included as part of the ingroup. The polarity of the characters was based on the outgroup comparison method, using Anthyllis as one outgroup and Tripodion as another. The analysis with Anthyllis as outgroup yielded eight equally parsimonious trees (with all characters equally weighted), each with 62 steps, a consistency index of 0.53, and a retention index of 0.75. All trees (including the strict consensus tree from the eight initial trees) showed that genus Lotus, subgenus Edentolotus, and sections Xantholotus and Erythrolotus are polyphyletic, with only section Krokeria appearing as monophyletic. On the other hand, the groups of species Lotus angustissimus, Lotus corniculatus, Lotus creticus, and Lotus peregrinus are monophyletic. Identical results were derived from the data matrix using Tripodion as the outgroup. Results are compared with previous cytogenetic and biochemical evidence.