Morphometric analysis of the <i>Solanum appendiculatum</i> species complex ( <i>Solanum</i> sect. <i>Anarrhichomenum</i> )

Abstract Solanum sect. Anarrhichomenum is a subclade of ca. 15 potato relatives consisting of both South American and Mesoamerican species groups. While crop species, such as potatoes and tomatoes, have been subject to intense research, other, more inconspicuous, viny, and less economically important lineages in the clade, such as S. sect. Anarrhichomenum , remain poorly understood. This study presents part of an ongoing effort to revise the Mesoamerican species of S. sect. Anarrhichomenum by determining species‐limits from morphological data. Mesoamerican S. sect. Anarrhichomenum consists of five historically recognized and one recently described species, which are grouped according to their morphological similarity to, and presumed common ancestry with the more well‐known, dioecious species S. appendiculatum . A numerical taxonomic analysis was performed on 53 morphological and 3 geographic variables taken from 273 herbarium collections, representing all known species of Mesoamerican S. sect. Anarrhichomenum ( S. appendiculatum , S. ionidium , S. skutchii , S. subvelutinum , S. tacanense , S. tavinuuyuku ), employing multivariate and univariate tests (PERMANOVA, Dunn's tests), ordination clustering (FAMD, NMDS), and random forest classification models. Results of this investigation recovered four morphologically coherent taxonomic units and disclosed the likely synonymy of the historically recognized species S. subvelutinum and S. tacanense with S. appendiculatum . Suites of statistically validated, taxonomically informative characters defining recovered morphospecies are presented, along with an in‐depth assessment of species limits within a mathematical framework.