Análisis morfométrico de Cestrum guatemalense, C. mexicanum y C. pacayense (Solanaceae)

There has been a taxonomic confusion among Cestrum guatemalense Francey, C. mexicanum Francey y C. pacayense Francey, species distributed in southern Mexico, Guatemala, Honduras and El Salvador. The difficulty in recognizing these species is partly due to the plasticity of some of its morphological characters; in fact, they have been proposed as synonyms. In order to differentiate these species, 158 samples of the herbariums F, IEB, MEXU, MO, NY, TEX and US were reviewed, evaluating 21 morphological characters, vegetative and floral, 15 of which approved positively for normality, homocedasticity and significant differences. With this information, principal component and discriminant analyses were performed. The characteristics related to the calyx and filaments of the stamens are the most important in both analyses. The principal component analysis presents 2 clusters, 1 of these only with specimens identified as C. mexicanum, which was corroborated by the discriminant analysis. For all these reasons, we consider the recognition of C. mexicanum as a species. Conversely, individuals of the other species remain as a complex of species that needs additional studies to determine its boundaries.