Three species of the isopod genus Astacilla were collected off Alborán Island (SW Mediterranean Sea) within the LIFE + INDE-MARES project. Twelve specimens of the rare species Astacilla carlosteroi (Reboreda, Wägele & Garmendia, 1994) were found; this species is only known as a single incomplete female from Galicia (NW Spain, Atlantic). Males, reported for the first time, are described, as well as morphological details provided for two additional species, A. dilatata (G.O. Sars, 1883) and A. mediterranea Koehler, 1911.