A new species of the genus Caprella (Crustacea: Amphipoda: Caprellidea) is described based on the specimens collected from the Strait of Gibraltar, southern Spain. The new species, Caprella caulerpensis, was found living in mud bottoms with the seaweed Caulerpa prolifera (Forskål) Lamouroux. Caprella caulerpensis can be distinguished from the most related species, Caprella rapax, mainly by the number of articles in the flagellum of antenna 1, the morphology of the dactylus of gnathopod 2 and the pereonites length.