This name is a synonym of Callitriche umbonata Hegelm..
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 31562) with original publication details: Verh. Bot. Vereins Prov. Brandenburg 10: 116 1868.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:429987-1.
This name was in version 1 of The Plant List, record kew-31562, and has not been changed.