Setarus was a planet in the Divergent Universe, taken over as a base of operations by Ondrokkon rebels. A portion of the planet was transplanted by the Divergence onto the planet Bortresoye, possibly adjacent to the zone containing Light City.
Reever plants were native to Setarus. Grelligs were transplanted here (likely unintentionally) from Ondrokkon. (AUDIO: The Twilight Kingdom)