Hello riquinhO:
Martio it is an early portuguese name - 1192 -All this to say that it could have happened the same with Marcos (coming from Marcus), Márcio (coming from Marcius)...
http://www.s-gabriel.org/names/juliana/earlyportuguese
Unless he´s the Prime Minister*coughs*we have for example Sócrates but more as a surname