Other additions since the provisional squad was announced last week are Casey Laulala, Heinke van der Merwe, Francois Louw and Ernst Joubert.
Among those sidelined by injury are Stephen Jones and Schalk Brits.
The tour opener against England on 27 May is followed by assignments against Ireland in Gloucester and Wales at the Millennium Stadium.
The Barbarians defeated all three countries in their most recent fixtures against them.
Barbarians' squad:
Backs - Isa Nacewa (Fiji), Mils Muliaina (New Zealand), Iain Balshaw (England), Cedric Heymans (France), Shane Williams (Wales), Paul Sackey (England), Sailosi Tagicakibau (Samoa), Casey Laulala (New Zealand), Mike Tindall (England), Damien Traille (France), Felipe Contepomi (Argentine), Stephen Donald (New Zealand), Rory Lawson (Scotland), Jerome Fillol (France)
Forwards - Benoit August (France), John Smit (South Africa), Aled de Malmanche (New Zealand), John Afoa (New Zealand), Duncan Jones (Wales), Neemia Tialata (New Zealand), Heinke van der Merwe (South Africa), Mark Chisholm (Australia), Mick O'Driscoll (Ireland), Anton van Zyl (South Africa), Pelu Taele (Samoa), Cornelius van Zyl (Italy), Raphael Lakafia (France), Akupusi Qera (Fiji), John Beattie (Scotland), Pedrie Wannenburg (South Africa), Ernst Joubert (South Africa), Francois Louw (South Africa)
Fixtures:
Sunday 27 May v England (Twickenham) 2.30pm
Tickets from www.ticketmaster.co.uk
Tuesday 29 May v Ireland (Kingsholm, Gloucester) 7.45pm
Tickets from www.gloucesterrugby.co.uk
Saturday 2 June v Wales (Millennium Stadium) 2.00pm
Tickets from www.ticketmaster.co.uk
