Antirrhinum is an Old World genus of up to 25 perennial taxa, mainly located in the western Mediterranean basin. A molecular analysis of 24 taxa of Antirrhinum was undertaken using cpDNA sequences from the trnT (UGU)-trnL (UAA) 5′ exon region. The Kimura two-parameter model was chosen to calculate pairwise nucleotide divergence values between cpDNA sequences, and a bootstrapped neighborjoining dendrogram was constructed from the nucleotide divergence distance matrix. Eighteen sites were variable across the studied samples and the position of 7 indels, ranging from 1 to 7 bp, was inferred from the sequence alignment. Several trnT-trnL sequences are identical in: some members of subsection Kickxiella (A. subbaeticum, A. valentinum, A. mollisimum, A. charidemi, and A. hispanicum); subsection Antirrhinum (A. australe, A. graniticum, and three subspecies of A. majus); and some species from subsection Kickxiella (A. lopesianum and A. molle) together with subsection Streptosepalum (A. braunblanquetii). Few supported clades were recovered from distance- or parsimony-based methods, all of which conflicted with traditional infrageneric splitting. Our cpDNA results are congruent with, but do not prove, the hypothesis of reticulation as one of the major processes to have occurred in the evolution of snapdragons, and suggest that other species in addition to those belonging to the A. majus group may also have been involved in the reticulation scenario.
