This name is a synonym of Rhododendron campanulatum subsp. aeruginosum (Hook. f.) D.F. Chamb..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50060455) with original publication details: Rhododendron Sikkim Himalaya 23, pl. 22 1849.
This name was in version 1 of The Plant List, record tro-50060455, and has not been changed.