This name is a synonym of Rhododendron nipponicum Matsum..
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Amer. Midl. Naturalist 30: 595 1943.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:326879-1.
This name was in version 1 of The Plant List, record kew-2667175.