RESUMEN

In this study, we analyzed the morphological affinities of the 24 species of Amphitecna based on detailed morphological studies and multivariate cluster analyses. Our results suggest that the genus Amphitecna includes six morphological groups that can be easily distinguished based on floral and fruits characteristics: A. donnell-smithii group, A. macrophylla group, A. megalophylla group, A. molinae group, A. spathicalyx group, and A. steyermarkii group. A new species from Mexico, Amphitecna fonceti, is described. This new species is clearly differentiated by the predominantly ramiflorous inflorescences bearing multiple flowers per shoot, buds rounded at the apex, large flowers with a transverse fold in the corolla throat, calyx surface pubescent and strongly costate, and fruits elliptic, apiculate at the apex. We discuss the characteristics of each morphological group and their geographical distribution, provide a detailed description of the new species including ethnobotany notes, and propose the re-establishment of the giant-leaved species A. megalophylla.