In Confluence 5.5.1/5.5.2, there is a a line of ')''s (parenthesis) under the Group Management (http://confluenceurl/admin/users/browsegroups.action) directly above the name heading of the groups table.

Their number is the number of groups listed in the table + 1 as we can see in the screenshot below:

PS: Tested in Confluence 5.5.3 version and the behaviour does not persist.