The Yamaguchi and K’maj classes of Fleet Ships are now available to fleets in-game.
The Yamaguchi Class, a fleet variant of the Ambassador Support Cruiser Retrofit, can be requisitioned by Federation Vice Admirals and The K’maj Class, a fleet variant of the Kamarag Battle Cruiser Retrofit, can be requisitioned by Klingon Lieutenant Generals. Each ship can be purchased individually for 20,000 Fleet Credits and four (4) Fleet Ship Modules from a Tier 3 Fleet Shipyard, and boasts increased Hull Hit Points, Shield Strength, an additional Science Console Slot, a Lt. Universal station in lieu of a Lt. Engineering station, and a unique Fleet Material.
More details about both ships, including stats, can be found in this Dev Blog.