This name is a synonym of Rumex stenophyllus Ledeb..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 26002583) with original publication details: Fl. URSS 5: 717 1936.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:697608-1.
This name was in version 1 of The Plant List, record tro-26002583, and has not been changed.