Aristolochia rzedowskiana Santana-Michel & Guzmán-Hernández is described as a new species from a locality near San Sebastián del Oeste and Puerto Vallarta in the State of Jalisco, Mexico; it belongs to Aristolochia sect. Gymnolobus subsect. Pentandrae. This species inhabits tropical subdeciduous forests and oak woods and can be identified by its perianth limb which is reddish, cordate-lanceolate, reflexed or straight, obtuse or attenuate towards the apex, with a papillose-reticulate surface and pale yellowish throat with dark spots. Its morphological characters relate it to Aristolochia variifolia, A. karwinskii and A. manantlanensis.
