This name is a synonym of Rhododendron arboreum var. roseum Lindl..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50060265) with original publication details: Pl. Asiat. Rar. 2: 23, pl. 123 1830.
This name was in version 1 of The Plant List, record tro-50060265.