This name is a synonym of Hammarbya paludosa (L.) Kuntze.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 465594) with original publication details: Ned. Kruidk. Arch. 56: 242 1949.
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 Hammarbya paludosa in version 1 of The Plant List.