This name is a synonym of Cosmos sessilis var. stellatus (Sherff) Melchert.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record EFFC6AE3-A5CB-4314-A7CC-6A21E2CAE712) with original publication details: Brittonia 16 70 1964.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:275160-2.
This name was in version 1 of The Plant List, record gcc-78851, and has not been changed.