May be moved back into Centaurea as a subgenus, see: Garcia-Jacas & al. (2006) Centaurea Revisited: A Molecular Survey of the Jacea Group. Ann Bot. 98(4): 741–753.
Now generally accepted as a synonym of Centaurea subgen. Cyanus or Centaurea sect. Cyanus - see Hassler as an example and Garcia-Jacas & al. (2006) However, a few authorities, mostly from Bulgaria, Turkey and Iran still prefer to segregate as expressed in Greuter, W. 2003. The Euro+Med treatment of Cardueae (Compositae) — generic concepts and required new names. Willdenowia 33(1): 49-61 PDF. There is a good case for following the consensus and place these combinations into Centaurea s.l.. However, a few recently described combinations have not been formally described as Centaurea species, for example, Cyanus ouramanicus Ranjbar & Negaresh, Ann. Bot. Fenn. 50(3): 161. (2013) would have to be Centaurea ouramanica (Ranjbar & Negaresh) comb. ined. as a provisionally accepted name or noted as unplaced. Andyboorman (talk) 20:09, 9 May 2018 (UTC)