ARIAS, SALVADOR1*, TERESA TERRAZAS2, and KENNETH M. CAMERON3. 1Jardin Botanico, Universidad Nacional Autonoma de Mexico, 70-140 Mexico D.F. 04510, MEX; 2Colegio de Postgraduados, Especialidad de Botanica, Montecillo, Estado de Mexico 56230, MEX; 3The New York Botanical Garden, Bronx, New York 10458-5126, USA. - Phylogeny of Pachycereus (Cactaceae) based in molecular data.
The phylogenetic relationships of Pachycereus species and
subtribe Pachycereinae were studied using DNA sequence data. A
parsimony analysis of chloroplast rpl-16 intron, trnL-F spacer, and
internal transcribed spacer (ITS) region were sequenced for 29
species, representing the four genera of subtribe Pachycereinae
(Carnegiea, Cephalocereus, Neobuxbaumia and
Pachycereus), plus three additional genera of subtribu
Stenocereinae, identified as closely related and used as outgroup.
Phylogenetic analysis did not support the monophyly of
Pachycereus with 12 species, including Anisocereus,
Backebergia, Lemaireocereus, Marginatocereus,
Mitrocereus and Pterocereus into its synonym. These
results support three major clades into Pachycereinae, one defined to
Pachycereus hollianus and P. lepidanthus, as the most
basal lineage into Pachycereinae species. A second clade was resolved
to Cephalocereus and Neobuxbaumia, with Pachycereus
fulviceps as sister taxon. The tree topology suggested a third
clade to Carnegiea, five Pachycereus species (here refer
as sensu stricto), plus other five Pachycereus species as well
as Stenocereus aragonii and S. eichalmii.
Key words: Cactaceae, Pachycereeae, Pachycereus, phylogeny