This name is a synonym of Callitriche longipedunculata Morong.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 330576) with original publication details: Man. Fl. Pl. Calif. 603 1925.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:42505-2.
This name was in version 1 of The Plant List, record kew-330576, and has not been changed.