A New Phylogenetic Hypothesis for Cereinae (Cactaceae) Points to a Monophyletic Subtribe

Cereinae comprises 14 genera distributed in Neotropical dry forest formations such as in the Caatingas of northeastern Brazil or in rocky outcrops in the north of southeastern Brazil. Historically, the taxonomy of the group has been very controversial, especially regarding generic circumscriptions, and phylogenetic relationships within the group are still poorly understood. To investigate the delimitation of the subtribe and infra-subtribal relationships, we performed a phylogenetic analysis including 50 taxa representing 13 genera using one nuclear (PhyC) and four cpDNA (petL-psbE, trnL-trnT, trnS-trnG, and rpl16) regions. Our results show a monophyletic Cereinae with high support in Bayesian, maximum parsimony, and maximum likelihood analyses based on combined matrices. Although our results expand the knowledge of generic relationships, we emphasize the need for further molecular phylogenetic studies combined with ecological evidence to clarify relationships at the more inclusive nodes of the subtribe.