This name is a synonym of Isoetes karstenii var. anomala (T.C. Palmer) R.L. Small & Hickey.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 26618776) with original publication details: Amer. Fern J. 22: 130 1933.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:130551-2.
This name was in version 1 of The Plant List, record tro-26618776, and has not been changed.