A taxonomic study of 147 examples previously classified as Lampanyctus crocodilus (Risso, 1810), captured both in the North Atlantic and in Mediterranean Sea, has revealed the existence of an unvarying series of meristic deviations between Mediterranean and Atlantic populations. The most important differences are found in gillrakers and AOa photophore counts, but there are also slight differences in dorsal and anal fin ray counts. The absence of clinal variation in the above mentioned meristic characters, even between specimens collected in the neighbouring areas of the Gulf of Cadiz and the Alboran Sea, seems to indicate a lack of genetic interchange between Atlantic and Mediterranean populations through the Strait of Gibraltar. In the light of these results, we propose Atlantic specimens belong to the species Lampanyctus gemmifer (Goode & Bean, 1879), a similar but different species from L. crocodilus, previously described from the Northwestern Atlantic. L. crocodilus is herein restricted to the Mediterranean.