This name is a synonym of Oenothera macrocarpa subsp. oklahomensis (Norton) W.L. Wagner.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50109239) with original publication details: Amer. J. Bot. 17(5): 365 1930.
This name was in version 1 of The Plant List, record tro-50109239.