This name is a synonym of Plectranthus barbatus var. grandis (L.H.Cramer) Lukhoba & A.J.Paton.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 45979) with original publication details: Abh. Königl. Akad. Wiss. Berlin 1891: 359 1892.
This name was in version 1 of The Plant List, record kew-45979, and has not been changed.