 Based on similarities in their claspers (male intromittent organs), the closest relative of the spined pygmy shark and the related "S. aliae" is thought to be the pygmy shark ("Euprotomicrus bispinatus").The spined pygmy shark has a wide distribution around the world.In the Atlantic Ocean, it occurs off Bermuda, the United States, Suriname, southern Brazil, and northern Argentina in the west, and off northern France, Madeira, Cape Verde, and the Azores in the east.