This name is a synonym of Isoetes maritima Underw..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 26604562) with original publication details: Amer. Fern J. 52: 121 1962.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:130510-2.
This name was in version 1 of The Plant List, record tro-26604562, and has not been changed.