The Battlestar Atlantia is Admiral Nagala flagship's during the Cylon attack. It is destroy over Virgon along with the rest of the remain Colonial Fleet. It is canon, however it class is not. In some dimension It is a Atlantia subclass, which is a subclass of the Nova Class Battlestar.
Battlestar Leonidas's UniverseEdit
The Battlestar Atlantia will been mention in Volume Five, during the Cylon attack. It is a Atlantia subclass.
Images is taking from Wolf Shipyard and was Created by CainsD. It is from Battlestar Prometheus (story).