Echeveria mendezii (Crassulaceae), a new species from southern Michoacán, Mexico

Background and Aims: Echeveria (Crassulaceae) is an American genus of ca. 204 species. Approximately 164 occur in Mexico, of which about 96% are endemic to the country, making it the center of diversification and endemism of the genus. Bibliographic research and exploration in the municipality Arteaga, Michoacán, led to the discovery of a species of Echeveria that does not correspond to any of those previously described. The objectives of the article are to describe a species of Echeveria as new to science, to compare it with E. sotoi, the morphologically similar species, and to evaluate its conservation status. Methods: Explorations were carried out in the regions where plants of the new species of Echeveria were located (Michoacán, municipality Arteaga), as well as in the type locality of E. sotoi (Michoacán, municipality Aquila), the morphologically most similar species. Morphological descriptions of the plants were prepared and specimens were herborized to deposit them in the herbaria IBUG, IEB, and MEXU. Morphometric analyses of leaves, bracts, cincinni and seeds were performed. Finally, the conservation status of the new species was assessed using the IUCN Red List Categories and Criteria. Key results: Echeveria mendezii is proposed as a new species to science. It is similar to E. sotoi; qualitative and morphometric analyses reveal significant differences in leaf, cincinni, calyx segments and seeds between the two. Echeveria mendezii is endemic to the Balsas Basin Province in Michoacán and assessed as Critically Endangered (CR). Conclusions: Echeveria mendezii belongs to the Gibbiflorae series. The species to which it most resembles is E. sotoi, where important discrepancies include the shape and color of the leaves, characteristics of the cincinni (total length, number of flowers, size of the peduncle and internodes), and the size of the seeds.