This name is a synonym of Sparganium eurycarpum subsp. coreanum (H.Lév.) C.D.K.Cook & M.S.Nicholls.
The record derives from WCSP
(data supplied on 2012-03-26)
which reports it as a synonym (record 455914) with original publication details: J. Jap. Bot. 12: 341 1936.
This name record (from WCSP) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Sparganium stoloniferum in version 1 of The Plant List.