This name is a synonym of Rhododendron hunnewellianum subsp. rockii (E.H. Wilson) D.F. Chamb..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 12305097) with original publication details: J. Arnold Arbor. 9(2–3): 103–104 1928.
This name was in version 1 of The Plant List, record tro-12305097, and has not been changed.