Diversity among members of the genus Sepiola (Cephalopoda: Sepiolidae) in the NE Atlantic-Mediterranean area is fairly high; 10 species have been recorded. In this paper, a new species, Sepiola bursadhaesa n. sp., is described based on ten specimens from the Catalan Sea. They are lodged in the Museo Nacional de Ciencias Naturales of Madrid. The new species is compared with the closely related species Sepiola affinis Naef, 1912 and Sepiola intermedia Naef, 1912, the latter of which is possibly its sister species. Male Sepiola bursadhaesa n. sp. differs from Sepiola intermedia in having a very wrinkled and outward projecting tubercle on the copulatory apparatus, and the first three (rather than two) suckers of the dorsal row of the distal part of the hectocotylus enlarged. The middle sucker of the three suckers is the largest. In female S. bursadhaesa n. sp., unlike all other species in the genus, the bursa copulatrix is fused throughout its posterior rim to the inner side of the mantle. The relationships between the species of the Sepiola atlantica group sensu Naef (1923), to which S. bursadhaesa n. sp. belongs, are described. An identification key for this group is provided.