This name is a synonym of Begonia lyallii A.DC..
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 362211) with original publication details: in Fl. Madag. 144: 76 1983.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:917619-1.
This name was in version 1 of The Plant List, record kew-362211.