Echinocereus enneacanthus var. dubius (Engelmann) L. D. Benson

Stems (5-)8-14(-15) cm diam.; ribs (7-)8-10(-12); areoles 18-52 mm apart. Spines: radial spines 5-8(-9) per areole, (22-)30-40(-47) mm; central spines 1-4(-5) per areole, 56-84(-96) mm.

Flowering (Mar-)Apr(-Aug); fruiting 3-4 months after flowering. Chihuahuan desert scrub, flats, rarely rocky slopes; 600-1800 m; Tex.; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí).