This name is a synonym of Centaurea raphanina subsp. mixta (DC.) Runemark.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 02FE7AB8-93C4-4D85-9CC7-C1E41E8B9EFA).
This name record (from TICA) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Centaurea mixta in version 1 of The Plant List.