This name is a synonym of Cyanus atratus (Willd.) Holub.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 54CEF9C9-CA0D-4ECB-8D8A-69E491D8E1DC).
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 atrata in version 1 of The Plant List.