Mammillaria carmenae (Isla Carmen pincushion cactus) is a species of flowering plant in the family Cactaceae. It is native to Tamaulipas state, in eastern central Mexico. It grows to 8 cm (3 in) tall by 15 cm (6 in) broad. The clustered egg-shaped stems, 3–4 cm thick, are covered in creamy yellow down and bristles. In spring they bear pale cream or pink-tinged flowers with yellow centres.