This name is a synonym of Schoenoplectus lacustris subsp. hippolyti (V.I.Krecz.) Kukkonen.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 262978) with original publication details: Fl. Kavkaza ed. 2, 2: 16 1940.
This name was in version 1 of The Plant List, record kew-262978, and has not been changed.