The tribe Hylocereeae are represented by mainly Central American-Mexican epiphytic, hemi-epiphytic and climbing cacti. They are popular due to their spectacular nocturnal flowers and have some importance as crops grown for their edible fruits. We present the first comprehensive phylogenetic study of the Hylocereeae sampling 60 out of the 63 currently accepted species and 17 out of 19 infraspecific taxa. Based on four plastid regions (trnK/matK, the rpl16 intron, rps3-rpl16, and trnL-F) we find a highly supported core Hylocereeae clade that also includes Acanthocereus and Peniocereus p.p., while Strophocactus is depicted as polyphyletic and is resolved outside of the Hylocereeae tribe. The clades found within Hylocereeae agree, in general terms, with the currently accepted genera but none of the genera are entirely monophyletic in their current circumscription. A new concept for the Hylocereeae is presented to include the genera Acanthocereus (incl. Peniocereus p.p.), Aporocactus, Disocactus, Epiphyllum, Selenicereus (incl. Hylocereus and Weberocereus p.p.), Pseudorhipsalis, Kimnachia gen. nov., and Weberocereus. New nomenclatural combinations are provided to make these genera monophyletic. The genus Deamia is reinstated for Strophocactus testudo and S. chontalensis, while Strophocactus is newly circumscribed to include S. wittii, Pseudoacanthocereus brasiliensis, and P. sicariguensis. Both genera are excluded from Hylocereeae. A taxonomic synopsis of Hylocereeae is provided.
This study aimed to test the phylogenetic relationships of the tribe Cacteae, the generic circumscription within the tribe, in particular, the monophyly of the genus Ferocactus, and to provide a biogeographical hypothesis about the origin of Cacteae. The analysis included 135 species from all of the 27 accepted genera and four outgroup species. Five chloroplast regions were sequenced, aligned, and coded postulating gaps, simple sequence repeats (SSRs), and inversions as potential synapomorphies, and their contributions to phylogenetic reconstruction were evaluated. The phylogenetic analyses recovered 63% of the genera as monophyletic. The contribution of rpl16, trnL-F and psbA to the phylogenetic signal was higher than in the two more slowly evolving genes (rbcL, matK), but the gaps and SSRs supported some of the genera. This result differs from those of previous phylogenetic studies in which less than 35% of the genera were recovered as monophyletic. In this work, Astrophytum and Echinocactus were re-circumscribed with five and four species, respectively. Turbinicarpus was found to be polyphyletic; 11 species correspond to Turbinicarpus s.str., whereas a highly supported clade corresponded to Rapicactus, and three species need further study. Contrary to its current circumscription, Ferocactus was not supported as monophyletic because it is polyphyletic concerning Glandulicactus, Leuchtenbergia, Stenocactus and Thelocactus. We recognize this group of genera as the Ferocactus clade in which the species share the presence of scales in the pericarpel and ribbed stems, whether tuberculated or not. The Cacteae seem to have originated in the Sierra Madre Oriental and then dispersed to the Mexican Plateau, where radiation and diversification occurred at the boundaries of the Miocene–Pliocene Epoch. The development of the Mexican Plateau and the Trans-Mexican Volcanic Belt may have favoured the isolation of the Cacteae. A taxonomic diagnosis is presented for the tribe Cacteae and 18 genera that we now recognize.