Molecular phylogeny of the Mammilloid clade (Cactaceae) resolves the monophyly of Mammillaria

To resolve more than 150 years of taxonomic confusion regarding the genus Mammillaria, the molecular phylogeny of the Mammilloid clade, including the genera Cochemiea, Coryphantha, Cumarinia, Escobaria, Mammillaria, Neolloydia, and Ortegocactus, is reconstructed. We included broad sampling of genera as well as a regionally nearly complete taxon sampling of Mammillaria and Cochemiea from the Baja California region. Employing the large single-copy region of the plastid genome as sequence data, we conducted maximum likelihood, maximum parsimony and Bayesian inference to reconstruct a molecular phylogeny of the clade. The molecular phylogenetic topology was further supported by reconstructing the ancestral states of 10 characters, from which three traditionally taxonomically important characters for the sampled taxa were selected. Results from our analyses clarify the evolutionary relationships of these closely related taxa, providing high resolution with strongly supported clades and subclades. The genus Mammillaria as currently circumscribed is non-monophyletic, and thus, we propose a recircumscription of the Mammilloid clade yielding three monophyletic genera, Mammillaria s.str., Cochemiea s.l. and Coryphantha. We herein make appropriate combinations to accommodate our circumscription of these genera.