Phylogenetic relationships in the genus Leonardoxa (Leguminosae : Caesalpinioideae) inferred from chloroplast trnL intron and trnL-trnF intergenic spacer sequences

The African genus Leonardoxa (Leguminosae: Caesalpinioideae) comprises two Congolean species and a group of four mostly allopatric subspecies principa lly located in Cameroon and clustered together in the L. africana complex. Leonardoxa provides a good opportunity to investigate the evolutionary hist ory of ant-plant mutualisms, as it exhibits Various grades of ant-plant int eractions from diffuse to obligate and symbiotic associations. We present i n this paper the first molecular phylogenetic study of this genus. We seque nced both the chloroplast DNA trnL intron (677 aligned-base pairs [bp]) and trnL-trnF intergene spacer (598 aligned bp). Inferred phylogenetic relatio nships suggested first that the genus is paraphyletic. The L. africana comp lex is clearly separated from the two Congolean species, and the integrity of the genus is thus in question. In the L. africana complex, our data show ed a lack of congruence between clades suggested by morphological and chlor oplast characters. This, and the low lever of molecular divergence found be tween subspecies, suggests gene how and introgressive events in the L. afri cana complex.