A new species, Brongniartia yahualica Dorado & D. M. Arias (Fabaceae, Faboideae), endemic to a small area of the state of Jalisco (known as Altos Sur) on the border with Zacatecas, Mexico, is described and illustrated. It has an unusual floral morphology, including a long and pendant semitubular shape and the largest flowers in the genus. Its morphological affinities with B. tenuifolia Standl. are discussed, and habitat data are given.