This name is a synonym of Plantago orbignyana subsp. pseudomollior (Rahn) Rahn.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50302092) with original publication details: Bot. Jahrb. Syst. 50: 256 1913.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:201451-2.
This name was in version 1 of The Plant List, record tro-50302092, and has not been changed.