This name is a synonym of Sparganium erectum subsp. microcarpum (Neuman) Domin.
The record derives from WCSP
(data supplied on 2012-03-26)
which reports it as a synonym (record 266024) with original publication details: Mitth. Thüring. Bot. Vereins n.f., 1: 84 1893.
This name was in version 1 of The Plant List, record kew-266024.