This name is a synonym of Mentzelia scabra subsp. grandiflora (Ruiz & Pav. ex G. Don) Weigend.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50294416) with original publication details: Gen. Hist. 3: 66 .
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:545411-1.
This name was in version 1 of The Plant List, record tro-50294416, and has not been changed.