Echinocereus rigidissimus (Engelm.) F. Haage Echinocereus rigidissimus (Engelm.) F. Haage, Special Offer (catálogo): 13. 1897 sec. Guzmán & al. 2003≡Cereus pectinatus var. rigidissimus Engelm. in Proc. Amer. Acad. Arts 3: 23. 1856 syn. sec. Guzmán & al. 2003