Arecent study of the molecular phylogeny of in the North Sea living Sepiolinae confirmed the occurrence of Sepietta oweniana, Sepietta neglecta, Sepiola pfefferi and Sepiola atlantica. Among the Sepiola atlantica samples a third Sepiola species was recognized for the first time. This undescribed species is genetically closely related to S. atlantica. Morphological studies have shown consistent differences in the length of the tentacular clubs, in the hectocotylus and in skin patterns. Ecological differences are mainly found in water depth. The newly recognized species is described here as Sepiola tridens sp. nov.