Usnia, a world covered in forests, was a planet found in the Usnia system. This system existed within the Senex sector, which itself was located in the Senex-Juvex region of the Western Reaches in the Mid Rim. Furthermore, Usnia's location was near the Tangles, a zone where many hyperlanes crossed paths. The planet could be reached through hyperspace from the Dornean, Trenthellix, and Varadan systems. House Petro, a noble family and one of the Ancient Houses of the Senex-Juvex area, designated the planet as a protected nature reserve.
The reference book The Essential Atlas, authored by Daniel Wallace and Jason Fry in 2009, included Usnia and pinpointed its location as grid square L-18.