LAUSR

PREMISE Pilosocereus (Cactaceae) is an important dry forest element occurring in all subregions and transitional zones of the Neotropics, with the highest diversity in eastern Brazil. The genus is subdivided into informal taxonomic groups; however, most of these are not supported by recent molecular phylogenetic inferences. This lack of confidence is probably due to the use of an insufficient number of loci and the complexity of cactus diversification. Here, we explored the species relationships in Pilosocereus in more detail, integrating multilocus phylogenetic approaches with the assessment of the ancestral range and the effect of geography on diversification shifts. METHODS We used 28 nuclear, plastid, and mitochondrial loci in 54 samples, representatives of 31 species. We performed concatenated and coalescent phylogenetic inferences and used Bayesian models to estimate the most likely ancestral range and diversification shifts. RESULTS All Pilosocereus species were clustered in the same branch, except P. bohlei. The phylogenetic relationships were more associated with the geographic distribution than taxonomic affinities among taxa. The genus began diversifying during the Plio-Pleistocene transition in the Caatinga domain and experienced an increased diversification rate during the Calabrian age. CONCLUSION We have recovered a well-supported multispecies coalescent phylogeny. Our results refine the pattern of rapid diversification of Pilosocereus species across Neotropical drylands during the Pleistocene and highlight the need for taxonomic rearrangements in the genus. We recovered a pulse of diversification during the Pleistocene that was likely driven by multiple dispersal and vicariance events within and among the Caatinga, Cerrado, and Atlantic Forest domains. This article is protected by copyright. All rights reserved.