This name is a synonym of Rhododendron riparioides (Cullen) Cubey.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 12304036) with original publication details: Notes Roy. Bot. Gard. Edinburgh 36(1): 123 1978.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:880146-1.
This name was in version 1 of The Plant List, record tro-12304036, and has not been changed.