This name is a synonym of Rhododendron rex subsp. gratum (T.L. Ming) M.Y. Fang.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50060114) with original publication details: Acta Bot. Yunnan. 3(1): 118–119, pl. 2, f. 1–5 1981.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:898602-1.
This name was in version 1 of The Plant List, record tro-50060114, and has not been changed.