Deletions in the plastid trnT-trnL intergenic spacer define clades within Cactaceae subfamily Cactoideae

The phylogenetic distribution of two deletions, of about 350 and 250 bp respectively, within the chloroplast trnT-trnL intergenic spacer was examined. One deletion was found in all members of Cactaceae subfamily Cactoideae sampled, totaling 37 species, but not in taxa from other subfamilies or closely related families. The second was shared by a subset of Cactoideae comprising members of tribes Cereeae, Trichocereeae, and Browningieae (in part), as well as Harrisia. Close links among the former three South American tribes have been previously hypothesized. This distribution suggested that Browningieae, a tribe defined largely by shared primitive features, were not monophyletic, and that Harrisia may have been incorrectly placed outside the Browningieae-Cereeae-Trichocereeae group.