The first frog to be limited was the Tribus, it was a limited edition pattern found only in presents during the first week of the game's release on 15 September 2010 and cannot be found in the pond.
The second frog breed to be limited in time was the Lanterna. On app startup, for Halloween 2010, this frog was sent to your in-game mailbox starting the 19th of October 2010.
The third frog breed limited in time was the Glacio. On app startup, starting the 9th of December 2010, Pocket Frogs offered a free download of the app Dizzypad and in exchange the player would recieve one Azure Albeo Glacio.