This name is a synonym of Callitriche truncata subsp. occidentalis (Rouy) Schotsman.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 31703) with original publication details: Fl. France 1: 39 1967.
This name was in version 1 of The Plant List, record kew-31703, and has not been changed.