Opuntia galapageia is endemic to the Galapagos Islands of Ecuador in western South America; in fact, the three subspecies of this taxon are all endemic to the Galapagos Islands. This species is the furthest west occurring of all the cactaceae family species in South America.
- C.Michael Hogan. 2011. Cactus. Topic ed. Arthur Dawson. Ed.-in-chief Cutler J.Cleveland. Encyclopedia of Earth. National Council for Science and the Environment. Washington DC http://www.eoearth.org/article/Cactus?topic=49480