This name is a synonym of Centaurea diffusa Lam..
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record D86EC705-BB49-493E-ACEE-771309AACE8C).
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 myriocephala in version 1 of The Plant List.