Gymnocalycium stenopleurum is a species of Gymnocalycium from Bolivia and Paraguay.
Gymnocalycium stenopleurum is a cactus species with gray-green, flattened, or spherical stems reaching up to 12 cm tall and 6âÂÂ12 cm wide. It has 8âÂÂ14 rounded ribs and 3âÂÂ6 twisted, light to dark brown radial spines measuring 0.7âÂÂ4 cm long, while central spines are typically absent. The plant produces white flowers 5âÂÂ7 cm long and gray-green fruits up to 4 cm long and 1 cm wide.
Native to Cerro León in Paraguay's Boquerón department and eastern Bolivia, it grows at altitudes of 10 to 500 meters.
Friedrich Ritter first described the species in 1979.