Polyphyly of the iconic cactus genus Turbinicarpus (Cactaceae) and its generic circumscription

Generic circumscription and species relationships in several lineages in Cactaceae tribe Cacteae remain unresolved. Turbinicarpus s.l. is one of the most species-rich genera in Cacteae, with its centre of distribution in the Chihuahuan Desert, Mexico. We reconstructed a phylogenetic tree of Turbinicarpus s.l. with Bayesian inference, using plastid DNA sequences and morphological characters, and inferred biogeographic history in order to understand their relationships. Our results supported the recognition of three different monophyletic lineages: Kadenicarpus, Rapicactus and Turbinicarpus. Kadenicarpus is endemic to the southernmost part of the Chihuahuan Desert in the states of Hidalgo and Queretaro. Rapicactus and Turbinicarpus are distributed in the main region of the Chihuahuan Desert where they have areas of overlap.