Leiostyla degenerata is a species of land snail in the family Lauriidae. It is endemic to Porto Santo Island in the Madeira archipelago.
This snail is found only on the slopes of Pico Branco, a mountain on the island. Its entire known range measures about 3 by 2 kilometers. It lives with other Leiostyla species in leaf litter and rock cracks. The population, though small, is likely stable and there are no immediate threats.