This name is a synonym of Najas marina var. intermedia (Wolfg. ex Gorski) Rendle.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 349481) with original publication details: Pl. Eur. 1: 18 1890.
This name was in version 1 of The Plant List, record kew-349481.