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Species delimitation in Cactaceae is a challenging task due to the proliferation of species and subspecies names. Echinocereus pulchellus occurs across a wide geographical range in Mexico and presents numerous polymorphisms. The species complex has been considered to comprise five subspecies. In the present work, we analyze morphological variation across the E. pulchellus complex to establish the taxonomic limits of the complex, to delimit taxa within it, and to determine whether morphological variation is associated with climate variables. Multivariate analyses of 50 morphological characters were conducting in a sample of ten populations representing all five of the previously recognized subspecies of the E. pulchellus complex. The results support the recognition of four distinct species, one of which contains two subspecies, and necessitate three new combinations: Echinocereus acanthosetus,E. sharpii, and E. weinbergii subsp. venustus. Six vegetative and two floral characters define the morphological limits between taxa. Correlation with climate variables was detected in the populations of E. weinbergii. [ABSTRACT FROM AUTHOR]

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Echinocereusis a morphologically diverse genus that includes 64 species grouped into eight taxonomic sections based on morphological traits. In previous molecular phylogenetic analyses, the relationships amongstEchinocereusspecies were not entirely revealed and useful characters to recognize clades were not provided. The inclusion of several sources of evidence in a phylogenetic analysis is likely to produce more supported hypotheses. Therefore, we performed a combined phylogenetic analysis with a set of 44 morphological characters and six chloroplast DNA sequences. Topologies from parsimony and Bayesian analyses were mostly congruent. However, the relationships ofE. poselgeriwere not consistent between analyses. A second Bayesian analysis using a long-branch extraction test resulted in a topology with the morphological position ofE. poselgericongruent with that in parsimony analysis. Parsimony and Bayesian analyses corroborated the monophyly ofEchinocereus, which included eight monophyletic groups. The combined phylogeny integrated into different clades those taxa that were not determined in previous analyses and changed the relationships of some recognized clades. The clades did not recover the recent infrageneric classification. In the present study, a new sectional classification forEchinocereusis proposed based on the eight recovered clades, which is supported by a combination of morphological and molecular characters. An identification key for sections in the genus is included. [ABSTRACT FROM AUTHOR]