Norway to Gibraltar, Azores to Mediterranean. Predator in the infralittoral and circalittoral. Original taxon: Murex costatus. Synonyms: atlantica, patula. The transition between the protoconch and the teleoconch is soft, with the very progressive emergence of the radial costae. – 30m deep, Punta de la Mona, east of La Herradura, Granada, Andalucia, S. Spain. 5,2mm.

Typical features: the pale base, the fine sculpture of spiral cords of equal strength, which often are almost invisible, separated from each other by a fine loom of extremely tiny microspirals. – Here, an example of the form “coarctata” Forbes (pale shell, weak brown subsutural band): 8m deep, a the edge of a Posidonia meadow, Tenda Bay, Itanos, Palaikastro, Sitia, NE. Crete. 6mm.