Hylocereus undatus (Haw.) Britt. & Rose subsp. luteocarpus Cálix de Dios is proposed as a new taxon from the dry deciduous forest of the Yucatan Peninsula. The new subspecies is described, illustrated, and its affinities discussed. It differs from H. undatus subsp. undatus by the presence of hairs in the areoles, greater number of spines, and yellow versus red fruit.