Resumen de Molecular phylogeny and taxonomy of the genus Disocactus (Cactaceae), based on the DNA sequences of six chloroplast markers
Miguel Ángel Cruz, Salvador Arias Montes, Teresa Terrazas
The genus Disocactus is native to Mexico and Central America and includes 11 species in four subgenera: D. subg. Ackermannia, D. subg. Aporocactus, D. subg. Disocactus and D. subg. Nopalxochia. Phylogenetic reconstruction was carried out with data from DNA sequences using the maximum parsimony and Bayesian inference criteria to explore the monophyly of the genus, its subgenera and its position within Hylocereeae. Six chloroplast markers (matK, psbA-trnH, rpl16, trnL-F, trnQ-rps16 and ycf1) were sequenced in ten species of Disocactus, 17 representatives from the remaining genera of Hylocereeae and five members of outgroups (Acanthocereus, Lemaireocereus and Pereskia). Our phylogenetic analysis supports neither the monophyly of Disocactus as it is currently defined nor that of the subgenera. The clade Disocactus s.str. was recovered for 13 species, including Epiphyllum anguliger, E. crenatum and E. lepidocarpum. Three subclades were observed within this clade, and three well-supported sister-species relationships were recovered: D. eichlamii and D. quezaltecus; D. biformis and D. nelsonii; and D. ackermannii and D. phyllanthoides. Disocactus speciosus subsp. aurantiacus was not recovered in the clade of D. speciosus. Epiphyllum and Pseudorhipsalis are identified as sister clades of Disocactus. Based on the obtained results, a new circumscription for Disocactus is proposed.
