This name is a synonym of Phoradendron leucarpum subsp. macrophyllum (Engelm.) J.R. Abbott & R.L. Thompson.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 19100434) with original publication details: Brittonia 16(1): 41 1964.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:194300-2.
This name was in version 1 of The Plant List, record tro-19100434.