Leptoms are a distinct evolutionary branch of golek-like mammals endemic to the Isle of Edeb. Though they undoubtedly share a common ancestor in deep pre-history with Lagoms, their evolutionary path was isolated from the more broadly settled goleks, who also split off from that biomorph. Leptoms, generally speaking, are telepathic mindspeakers to varying degrees. They are also generally sable or black in color, and seem to be able to interbreed successfully with their more domesticated golek cousins. For this reason, the term Sable goleks is generally used in modern contexts.
Archef was a famous Leptom chief whose people aided the Muses and the Order of the Tempest during the Fall of Hard Hammer (Elgorra), which resulted in the breaking of the Stem of Edeb, the inversion and wandering of that island, resulting finally in collision with the Greater Kremellian Subcontinent. Following this collision, and the inter-linking of Edeb with the mainland, leptoms intermarried with goleks, and thus the term Leptom is used most often to refer to pre-contact era biomorphs from Edeb.
Machef, the sable golek, is the great grand-son of Archef.