A new endemic species of Acanthocereus (Cactaceae) from southern Jalisco, Mexico Author González-Zamora, Pedro 0000-0002-2702-5828 C. P. 28450, Comala, Colima, Mexico. & gonzalezambiental @ gmail. com; https: // orcid. org / 0000 - 0002 - 2702 - 5828 gonzalezambiental@gmail.com Author Rodríguez-Contreras, Aarón 0000-0003-1805-7403 Herbario “ Luz María Villarreal de Puga ” (IBUG), Instituto de Botánica, Universidad de Guadalajara. Km 15.5 carretera a Nogales, Predio Las Agujas, 45200 Zapopan, Jalisco, Mexico. & aaron. rodriguez @ academicos. udg. mx; https: // orcid. org / 0000 - 0003 - 1805 - 7403 aaron.rodriguez@academicos.udg.mx Author Sánchez, Daniel 0000-0002-8621-0222 Herbario “ Luz María Villarreal de Puga ” (IBUG), Instituto de Botánica, Universidad de Guadalajara. Km 15.5 carretera a Nogales, Predio Las Agujas, 45200 Zapopan, Jalisco, Mexico. & CONACYT, Laboratorio Nacional de Identificación y Caracterización Vegetal, Departamento de Botánica y Zoología, Universidad de Guadalajara, 45200 Zapopan, Jalisco, Mexico. & dsanchezc @ conacyt. mx; https: // orcid. org / 0000 - 0002 - 8621 - 0222 dsanchezc@conacyt.mx text Phytotaxa 2021 2021-10-07 522 2 131 138 journal article 4106 10.11646/phytotaxa.522.2.5 69f4a6ac-2282-4d71-81ed-a0b081473273 1179-3163 5556253

TABLE 1. Morphological comparison between Acanthocereus atropurpureus and related species, with distribution area.

	A. atropurpureus	A. castellae	A. cuixmalensis	A. paradoxus
Plant height (m)	0.7–2.0	0.5–2.0	0.8–2.5	0.5–1.2
Diameter of the stem (cm)	0.8–1.6	1.9 –3.0	1.8–3.5	0.5–0.9
Number of ribs	3–4 ribs with sinuate margins	3 ribs with straight margins	3-4 ribs with sinuate margins	Cylindrical stem, 3–4 ribs with straight margins when dehydrated
Color of the stem	Dull green/purple or pink	Light green	Dull green with purple zones	Dull green/purple with darker margins
Number of central spines	3–4(–5)	4–6	4–6(–7)	(3–)4(–5)
Length of central spines (mm)	0.9–1.3	5.0–25	7.0–15	0.6–1.6
Number of radial spines, orientation	2, lower part	2, lower part	2, lower part	2, lower part
Flower length (cm)	9–10	11	9–11	9
Orientation of the inner tepals	Inclined to ascending	Ascending	Ascending	Reclined to descending
Fruit size: length / diameter (cm)	5.0–5.5 / 3.0–3.5	4 / 2	5 / 3	4–6 / 2.5
Distribution area	Jalisco	Colima/Michoacán/ Guerrero	Colima//Jalisco/ Michoacán	Jalisco