This name is a synonym of Penstemon cardinalis subsp. regalis (A. Nelson) G.T. Nisbet & R.C. Jacks..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50104107) with original publication details: Amer. J. Bot. 21(9): 578–579 1934.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187730-2.
This name was in version 1 of The Plant List, record tro-50104107.