This name is a synonym of Mimulus guttatus var. puberulus (Greene) A.L. Grant.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50102062) with original publication details: Leafl. Bot. Observ. Crit. 2(1): 4 1909.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:806074-1.
This name was in version 1 of The Plant List, record tro-50102062, and has not been changed.