This name is a synonym of Karwinskia umbellata (Cav.) Schltdl..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50201734) with original publication details: Icon. 6: 2, t. 504 1800.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:718723-1.
This name was in version 1 of The Plant List, record tro-50201734, and has not been changed.