Phylogenetic relationships in the cactus family (Cactaceae) based on evidence from trnK/matK and trnL-trnF sequences

Cacti are a large and diverse group of stein succulents predominantly Occurring in warm and and North and South America. Chloroplast DNA sequences of the trnK intron including the matK gene, were sequenced for 70 mgroup taxa and two outgroups from the Portulacaceae In order to improve resolution in three major groups of Cactoideae, trnL-trnF sequences from members of these clades were added to a combined analysis The three exemplars of Pereskia did not form a monophyletic group but a basal grade The well-supported subfamilies Cactoideae and Opuntioideae and the genus Mathuema formed a weakly supported clade sister to Pereskia The parsimony analysis supported a sister group relationship of Mathuema and Opuntioideae, although the likelihood analysis did not. Blossfeldia, a monotypic genus of morphologically modified and ecologically specialized cacti, was identified as the sister group to all other Cactoideae. The tribe Cacteae was found to be sister to a largely unresolved clade comprising the genera Calymmanthium, Copiapoa, and Frailea. As well as two large and well-supported clades Browningta sensu stricto (excluding Castellanosta), the two tribes Cereeae and Trichocereeae and parts of the tribes Notocacteae and Rhipsalideae formed one clade The distribution of this group is largely restricted to South America The other clade consists of the columnar cacti of Notocacteae, Various genera of Browningieae, Echinocereeae, and Leptocereeae the tribes Hylocereeae and Pachycereeae and Pfeiffera A large portion of this latter croup occurs in Central and North America and the Caribbean.