This name is a synonym of Plagiorhegma dubium Maxim..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 3500347) with original publication details: J. Linn. Soc., Bot. 17(102): 377 1879.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:107347-1.
This name was in version 1 of The Plant List, record tro-3500347, and has not been changed.