A new species of <i>Amphitecna</i> (Bignoniaceae) endemic to the mountain karst forests of southern Mexico

Amphitecna brevicalyx (Bignoniaceae), a new tree species endemic to Mexico is described and illustrated. Its cauliflorous inflorescences, featuring a single flower per shoot and funnelform corollas without a transverse fold in the throat, place it within the Amphitecna macrophylla group. This species is distinguished by its large corollas and a spathe‐like, circumscissile calyx that is soon deciduous – features not previously reported in the Mexican Amphitecna species. Moreover, its remarkably reduced calyx, covering less than one‐fourth of the length of the corolla, is unique among all known species of the genus. Its conservation status and morphological similarities are discussed. The species is found only in the humid karst forests of southern Mexico, recognized as centers of endemism where unusual traits frequently evolve.