**7. Acknowledgements**

We would like to thank Kelly Gutseit and Cesar B. Daniel for their valuable comments and suggestions. We are grateful to many colleagues for their substantial help with discussions, support in the office or in the field in some of the our surveys (Alan Y. Mocochinski, Daros A. T. da Silva, Joachim Graf Neto, Juarez Michelotti, Marcelo Brotto, Marília Borgo, Pablo M. Hoffmann, Rafael D. Zenni, Renata C. de Sousa, Ruddy T. Proença, Kelly G. Martins, Franklin Galvão, Carlos V. Roderjan, Otávio A. Bressan and Charles Carneiro).
