This name is a synonym of Radula retroflexa var. fauciloba (Stephani) K. Yamada.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 35209483) with original publication details: Sp. Hepat. 4: 188 1910.
This name was in version 1 of The Plant List, record tro-35209483.