A molecular phylogenetic approach to the systematics of Cylindropuntieae (Opuntioideae, Cactaceae)

Previous taxonomic schemes for the Cylindropuntieae were re-evaluated in the light of a molecular phylogeny derived from a Bayesian, maximum-likelihood and parsimony reconstructions with three plastid regions (atpB-rbcL, psbA-trnH and trnK/matK data sets). The reconstruction revealed that Corynopuntia and Grusonia as currently defined were polyphyletic. Quiabentia, Micropuntia, Pereskiopsis and Cylindropuntia were the only genera recovered as monophyletic. Grusonia s.s. (only including G. bradtiana) is nested in a polytomy with the rest of the species of Corynopuntia. Grusonia s.l. (G. bradtiana plus Corynopuntia) and Corynopuntia as currently defined are polyphyletic because G. pulchella is sister to Pereskiopsis. Some previous taxonomic proposals for Cylindropuntia and Grusonia recognized polyphyletic series and subgenera that do not conform to the strongly supported monophyletic groups here recovered. This study proposes redefining the polyphyletic Grusonia excluding G. pulchella in order to recognize a strongly supported monophyletic genus and the acceptance of a monotypic Micropuntia (G. pulchella) avoiding a new combination into Pereskiopsis. The infrageneric classification for Grusonia is discussed and the recognition of only four monophyletic strongly supported series (Bigelovianae, Imbricatae, Leptocaules and Ramosissimae) for Cylindropuntia is presented.