this will not be listed since the clients are not yet installed with SEP. once you install SEP the client will start reporting its status to SEPM.
you can use feature to find unmanaged detector,
What does it mean to set a client as an Unmanaged Detector?
http://www.symantec.com/docs/TECH105722
Find Unmanaged Clients on a remote network location using the Unmanaged Detector
http://www.symantec.com/docs/TECH96234
Setting notifications when using the "Unmanaged Detector" feature in the SEPM
http://www.symantec.com/docs/TECH104897