This name is a synonym of Begonia unduavensis Rusby.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 362129) with original publication details: Descr. S. Amer. Pl. 65 1920.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:30706-2.
This name was in version 1 of The Plant List, record kew-362129, and has not been changed.