This name is a synonym of Centranthus ruber subsp. sibthorpii (Heldr. & Sart. ex Boiss.) Hayek.
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Consp. Fl. Graec. 1: 747 1901.
This name was in version 1 of The Plant List, record kew-2709048.