Floristic and phytosociological studies of the Arequipa region. Part of the results are published in: Montesinos-Tubee, D. B., Sýkora, K. V., Quipuscoa-Silvestre, V., & Cleef, A. M. (2015). Species composition and phytosociology of xerophytic plant communities after extreme rainfall in South Peru. Phytocoenologia, 45(3), 203-250.
I think that it is Cereus peruvianus cristata or C p Monstrosus- Inat is not accepting either name (not in database?)
can’t find any good images in the wild - only nursery specimens