Mario among notable Portugal inclusions
The 21-year-old is yet to represent his nation at senior level, but could make his debut in Brazil.
However, there is no room for Porto prospect Josue, who was part of the squad for the qualifying play-off with Sweden that saw Portugal book their place at the finals.
Bento has opted for plenty of depth when it comes to attacking options.
As well as Ballon d'Or winner Cristiano Ronaldo, the coach has nine other forwards in his provisional squad, including Porto's Ricardo Quaresma and Manchester United's Nani as well as experienced striking pair Helder Postiga and Hugo Almeida.
Real Madrid defenders Fabio Coentrao and Pepe are predictably included, together with midfielders Raul Meireles, William Carvalho and Joao Moutinho.
Bento's men get their Group G campaign under way against Germany in Salvador on June 16, with the squad due to be cut to 23 on Monday.
Squad in full:
Goalkeepers: Anthony Lopes (Lyon), Beto (Sevilla), Eduardo (Sporting Braga), Rui Patricio (Sporting Lisbon)
Defenders: Andre Almeida (Benfica), Vitorino Antunes (Malaga), Bruno Alves (Fenerbahce), Fabio Coentrao (Real Madrid), Joao Pereira (Valencia), Neto (Zenit), Pepe (Real Madrid), Ricardo Costa (Valencia), Rolando (Inter)
Midfielders: Andre Gomes (Benfica), Joao Mario (Victoria Setubal), Joao Moutinho (Monaco), Miguel Veloso (Dynamo Kiev), Raul Meireles (Fenerbahce), Ruben Amorim (Benfica), William Carvalho (Sporting LIsbon)
Forward: Cristiano Ronaldo (Real Madrid), Eder (Braga), Helder Postiga (Lazio), Hugo Almeida (Besiktas), Ivan Cavaleiro (Benfica), Nani (Manchester United), Rafa (Braga), Ricardo Quaresma (Porto), Varela (Porto), Vieirinha (Wolfsburg)