Maihuenia + Greek –opsis ‘looking like’. For the resemblance to Maihuenia. “This genus is intermediary between the genus Maihuenia, of which it has all the appearance with its fused and non-separable segments, and certain Opuntiae of the section Tephrocactus, with which it shares the possession of some areoles armed with tufts of glochids as in Opuntia glomerata and Opuntia molinensis.”
Maarten H.J. van der Meer (2023 Jul 14). Maihueniopsis. Dictionary of Cactus Names. Retrieved from https://www.cactusnames.org/Maihueniopsis