Prionosciadium guzmanianum (Apiaceae, Apioideae), a new species with red flowers from western Mexico

Prionosciadium guzmanianum, a second species of Prionosciadium with red flowers is described and illustrated. The genus is almost endemic to the Mexican Republic and presents a high richness and endemism in western Mexico. Given the color of its flowers, the closest relationship of the new species is with P. tamayoi, from which it differs by the basal, ternate‐pinnatifid leaves, pinnatifid leaflets and larger orbicular fruits with central dorsal rib wing. Pollen grains are described and illustrated, and information on the habitat of the species is provided.