The Atlantic sawtail catshark (Galeus atlanticus) is a little-known species of catshark, part of the family Scyliorhinidae, found in a small area of the northeastern Atlantic Ocean, centered on the Strait of Gibraltar and the Alborán Sea. It is found on or close to the bottom over the continental slope, mostly at depths of . This shark closely resembles, and was once thought to be the same species as, the blackmouth catshark (G. melastomus); both are slender with a series of dark saddles and blotches along the back and tail, and a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin. It differs subtly from G. melastomus in characters including snout length, caudal peduncle depth, and the color of the furrows at the corner of its mouth. Reproduction in the Atlantic sawtail catshark is oviparous, with females carrying multiple maturing eggs at once. Mating and spawning occur year-round. This species is caught incidentally by commercial deepwater fisheries throughout its range, but the impact of fishing pressure on its population is uncertain as it is not recorded separately from G. melastomus. Given its restricted distribution, it has been assessed as Near Threatened by the International Union for Conservation of Nature (IUCN). Taxonomy The original description of the Atlantic sawtail catshark, as Pristiurus atlanticus, was published in 1888 by French naturalist Léon Louis Vaillant, in Expéditions scientifiques du "Travailleur" et du "Talisman" pendant les années 1880, 1881, 1882, 1883. Vaillant based his account on a specimen caught at a depth of off Cape Spartel in northwestern Morocco. This species was long thought to be the same as the closely similar blackmouth catshark (G. melastomus), until it was resurrected by Ramón Muñoz-Chápuli and A. Perez Ortega in 1985. Castilho and colleagues (2007) further affirmed the distinction between G. atlanticus and G. melastomus using morphometric and mitochondrial DNA data. Distribution and habitat The Atlantic sawtail catshark is found from Cape St. Vincent in southwestern Portugal, through the Strait of Gibraltar into the Alborán Sea, to as far as Cabo de Gata in southwestern Spain. It is most abundant in the center of the Alborán Sea, and around Isla de Alborán. This species has been recorded a few times off Morocco and once off Mauritania; it may be extremely rare or mistaken for G. melastomus in the region. Its total range has been estimated to encompass , about evenly divided