Resumen

JORGE-CRUZ, Coral Yamileth; FERNANDEZ-NAVA, Rafael  y  ARREGUIN-SANCHEZ, María de la Luz. Contribution to the taxonomy of mexican species of Colubrina (Rhamnaceae) based on leaf architecture and epidermal surfaces. Polibotánica [online]. 2025, n.59, pp.15-41.  Epub 29-Abr-2025. ISSN 1405-2768.  https://doi.org/10.18387/polibotanica.59.2.

The leaf architecture and epidermal surfaces of the leaf blade of nine species of Colubrina species naturally distributed in Mexico were described. They belong to two subgenera and three sections: the subgenus Colubrina includes the species C. arborescens (Section Colubrina); C. elliptica, C. heteroneura, C. johnstonii and C. viridis (Section Cowania); as well as C. ehrenbergii and C. triflora (Section Barcena). On the other hand, the subgenus Serrataria includes C. californica and C. celtidifolia The taxa were separated by characters such as venation types, branching or not of the first pair of lower secondary veins, number of secondary veins on the leaf surface, absent or present trichomes, with modified epidermal cell radial base or without radial base of epidermal cells, presence or absence of glands in the leaf blade, contour of the epidermal cell walls (straight or wavy), presence or absence of free veins in the third and fourth category veins, as well as the types of stomata.

A dichotomous key and a clustering analysis using the UPGMA method, Jaccard's similarity index, together with its respective dendrogram, were included, with which three main groups were identified: the first with the species of Cowania and Barcena sections; the second groups with C. arborescens of the Colubrina section together with the nine species of the Serrataria subgenus; and the third separates the species of the subgenus Serrataria into two subgroups according to the venation pattern. The presence of C. arborescens in the second group was attributed to the differences observed in the specimens from southern Mexico, compared to the Caribbean taxa, indicating that the specimens from the Mexican Republic are a different taxon or belong to another section of the subgenus Colubrina. The species of the subgenus Serrataria do not have glands on the teeth, which is a fundamental character mentioned in the literature and the protuberances of the teeth are due to the penetration of a secondary or tertiary vein inside them. This suggests the need for a redescription or relocation of this subgenus.

Palabras llave : Subgenus Serrataria; Subgenus Colubrina; venation types; trichomes; glands.

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