This name is a synonym of Rhododendron augustinii subsp. chasmanthum (Diels) Cullen.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 12303877) with original publication details: J. Bot. (Morot) 12(17–18): 261 1898.
This name was in version 1 of The Plant List, record tro-12303877, and has not been changed.