Polystemma stevensii (Apocynaceae, Asclepiadoideae), a new species from Michoacán, Mexico Author Hernández-Barón, Gerald Matus 0000-0002-2004-2158 Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Camino Ing. Ramón Padilla Sánchez 2100, Las Agujas 45200, Zapopan, Jalisco, Mexico & ghernandezbaron @ gmail. com; https: // orcid. org / 0000 - 0002 - 2004 - 2158 ghernandezbaron@gmail.com Author Juárez, Diana Isabel Trujillo 0000-0001-8092-6505 Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Camino Ing. Ramón Padilla Sánchez 2100, Las Agujas 45200, Zapopan, Jalisco, Mexico & dianatrujillo 2311 @ gmail. com; https: // orcid. org / 0000 - 0001 - 8092 - 6505 dianatrujillo2311@gmail.com Author Steinmann, Victor W. 0000-0003-0103-9575 Instituto de Ecología, A. C., Centro Regional del Bajío, Av. Lázaro Cárdenas 253, 61600 Pátzcuaro, Michoacán, Mexico & steinmav @ gmail. com; https: // orcid. org / 0000 - 0003 - 0103 - 9575 steinmav@gmail.com text Phytotaxa 2023 2023-09-13 613 2 194 200 https://phytotaxa.mapress.com/pt/article/download/phytotaxa.613.2.9/51090 journal article 10.11646/phytotaxa.613.2.9 1179-3163 Key to species of Polystemma of Michoacán , Mexico 1. Plants suffruticose, although vining at the branch ends; leaf blades less than 2 cm long and wide; flowers with the corolla lobes abaxially reticulate yellow-blackish or burgundy red ................................................................................................. P . fishbeiniana - Plants vining; leaf blades more than 2 cm long and wide; flowers with the corolla lobes abaxially not reticulate...........................2 2. Corona lobes with a pair of falcate appendages ........................................................................................................ P . guatemalense - Corona lobes with a pair of filiform appendages ...............................................................................................................................3 3. Corolla lobes ovate, glabrous adaxially, corolla tube purple, gynostegial corona fused at the base but without a discontinuous flat ring, style apex flat ....................................................................................................................................................... P . viridiflorum - Corolla lobes lanceolate, sericeous adaxially, corolla tube white or yellowish, gynostegial corona fused at the base to form a discontinuous flat ring, style apex conspicuously globose................................................................................................ P . stevensii