This name is a synonym of Rumex aquaticus subsp. arcticus (Trautv.) Hiitonen.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50118288) with original publication details: Fl. Arct. URSS 5: 155 1966.
This name was in version 1 of The Plant List, record tro-50118288, and has not been changed.