This name is a synonym of Penstemon guadalupensis var. ernestii (Pennell) Cory.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50079555) with original publication details: Acad. Nat. Sci. Philadelphia Monogr. 1: 252–253, map 64 1935.
This name was in version 1 of The Plant List, record tro-50079555.