A new species of Cumulopuntia (C. flexibilispina) from north-west Bolivia, which forms hemispherical clumps with dense flexible white spination, is described and illustrated. The species is only known from very high elevations between 4,400m and 4,650m. The new species is compared with and key differences are noted from four other high elevation cumulopuntias: the widespread C. boliviana (including C. boliviana subsp. dactylifera) from Peru, Bolivia and Argentina; C. glomerata (C. boliviana subsp. ignescens) which is found at similar high elevations but in more arid conditions further to the west in Peru, Bolivia and Chile; C. chichensis from southern Bolivia and northern Argentina and finally C. echinacea from southern Peru and northern Chile.