This name is a synonym of Penstemon stenosepalus (A. Gray) Howell.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50107893) with original publication details: Proc. Amer. Acad. Arts 6: 70 1862.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:187439-2.
This name was in version 1 of The Plant List, record tro-50107893, and has not been changed.