Arion luisae, is a large terrestrial gastropod mollusk in the family Arionidae, the round back slugs.
The length of the species attains 45 mm.
The creature has a brownish-gray color with bands. Its head and tentacles are the same color as the background. It has a grayish border or fringe. The mucus is colorless.
This species occurs in the eastern coastal areas of Spain.