This name is a synonym of Mimulus tenellus var. platyphyllus (Franch.) Tsoong.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50056794) with original publication details: Pl. David. 2: 103 1888.
This name was in version 1 of The Plant List, record tro-50056794.