This name is a synonym of Penstemon angustifolius var. venosus (D.D. Keck) N.H. Holmgren.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 29204302) with original publication details: J. Wash. Acad. Sci. 29(11): 490 1939.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187151-2.
This name was in version 1 of The Plant List, record tro-29204302.