Quetzalcoatlia (Crassulaceae), high small-scale diversification in western Mexico: a synopsis with four new species

The genus Quetzalcoatlia was recently segregated from the paraphyletic genus Graptopetalum and consists of six species, confined to western Mexico, in the states of Jalisco, Michoacán and Colima (Vázquez-García et al. 2023). The alpha-taxonomy of Quetzalcoatlia (Crassulaceae, Saxifragales) has been summarized below, which includes the addition of four new species: Q. grulloensis and Q. santanamichelii from the state of Jalisco, and Q. itzicuaroensis and Q. latipetala from the state of Michoacán. One species is endemic to the state of Colima (Q. glassii); five species are endemic to the state of Jalisco (Q. grulloensis, Q. rosanevadoensis, Q. superba, Q. santanamichelii, and Q. trujilloi); three are endemic to the state of Michoacán (Q. itzicuaroensis, Q. kristenii, and Q. latipetala), and one is from unknown origin (Q. pentandra), only confirmed from cultivated material at the Huntington Botanical Garden. Quetzalcoatlia, through a pattern of allopatric speciation, exhibits a high small-scale diversification in western Mexico, with all ten species confined within a radius of ca. 100 km. The Quetzalcoatlia species have potential for horticulture in subtropical and tropical areas. The study provides a distribution map, habitat and phenology data, and a key to species of Quetzalcoatlia. Additionally, the conservation status of each species was evaluated. The results have implications for understanding Quetzalcoatlia biogeography and its adaptive radiation in western Mexico.