Leaf morphological variation of Jaltomata (Solanoideae: Solanaceae) in Mexico: usefulness in species recognition

Jaltomata Schltdl. is the sister genus of Solanum L., and maintains important wild traits, as well as great potential for application in plant breeding issues by conserving a relevant genetic pool. In Mexico, the taxonomic ambiguity in the group has limited their knowledge and correct management. Plant morphology is essential to detect diagnostic characters for species delimitation. Leaves are highly variable organs and fundamental in taxonomy. Here, we evaluate whether leaf characters allow the recognition of Mexican species of Jaltomata. We analysed 11 possible diagnostic characters, five quantitative and six qualitative, extracted from taxonomic literature and leaf architecture manuals. The data were analysed using a linear discriminant analysis, hierarchical cluster analysis, and permutational multivariate analysis of variance. Our results show significant segregations in Jaltomata grandiflora (B.L.Rob. & Greenm.) D’Arcy, Mione & Tilton Davis, J. bohsiana Mione & D.M.Spooner, and J. chihuahuensis (Bitter) Mione & Bye, while the characters evaluated only allowed a partial delimitation between J. procumbens (Cav.) J.L.Gentry and J. repandidentata (Dunal) Hunz. Additionally, J. darcyana Mione, and one morphotype (Bohsiana1 group) were detected. The margin, the abundance of pubescence, the pubescence in the secondary veins, the shape and angle of the apex, as well as the leaf length × width ratio turned out to be the characters with the highest discriminate value. We provide the first foliar key for Mexican Jaltomata species and conclude that leaf morphological traits are an important criterion to consider and they should be included in the taxonomic keys of the genus.