This name is a synonym of Spirodela polyrrhiza (L.) Schleid..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 18100060) with original publication details: J. Phys. Chim. Hist. Nat. Arts 82: 113 1816.
This name was in version 1 of The Plant List, record tro-18100060.