This name is a synonym of Sparganium erectum subsp. neglectum (Beeby) K.Richt..
The record derives from WCSP
(data supplied on 2012-03-26)
which reports it as a synonym (record 266116) with original publication details: J. Bot. 23: 26 1885.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:836779-1.
This name was in version 1 of The Plant List, record kew-266116, and has not been changed.