This name is a synonym of Penstemon cobaea subsp. purpureus (Pennell) Pennell.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 29200166) with original publication details: Proc. Acad. Nat. Sci. Philadelphia 73(3B): 490 1921.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187278-2.
This name was in version 1 of The Plant List, record tro-29200166.