This name is a synonym of Rhododendron molle subsp. japonicum (A.Gray) Kron.
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Mem. Amer. Acad. Arts n.s., 6: 400 1859.
This name was in version 1 of The Plant List, record kew-2667121.