Phylogeny in Echinocereus (Cactaceae) based on combined morphological and molecular evidence: taxonomic implications

Abstract

Echinocereus is a morphologically diverse genus that includes 64 species grouped into eight taxonomic sections based on morphological traits. In previous molecular phylogenetic analyses, the relationships amongst Echinocereus species 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 of E. poselgeri were not consistent between analyses. A second Bayesian analysis using a long-branch extraction test resulted in a topology with the morphological position of E. poselgeri congruent with that in parsimony analysis. Parsimony and Bayesian analyses corroborated the monophyly of Echinocereus, 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 for Echinocereus is 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.

Key words:

• Bayesian inference
• combined analyses
• Echinocereus poselgeri
• Echinocereeae
• long-branch attraction
• long-branch extraction
• morphology
• parsimony
• taxonomy
• Wilcoxia

Acknowledgements

We thank the curators of ARIZ, ASU, CIIDIR, IBUG, MEXU, and UNM for loaning specimens; Emiliano Sánchez (Jardín Botánico Regional de Cadereyta) and Mario Mendoza (Jardín Botánico Charco del Ingenio) for sampling the living collection. We are grateful to Berenit Mendoza (Instituto de Biología, UNAM) for SEM pictures; José Delgadillo (Universidad Autónoma de Baja California) for helping in fieldwork; Wolfgang Blum and Michael Lange (Der Echinocereenfreund) provided useful information; Martha Martínez (Facultad de Ciencias, UNAM) and Rosaura Grether (UAM-I) made relevant comments in a draft version. DS thanks Juan Sánchez for assistance with the computational problems. We also thank the suggestions of two anonymous reviewers, which improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2017.1343260