Who were the American mafia members whose roots where from Napoli region rather than Sicilian?
I know of Capone, V.Genovese, the Gottis.
Which of the more well known guys also were?
there were/are thousands
This is very true. Southern Italians in general dominated the composition of the mafia in America. I believe The Godfather put more of an emphasis on Sicilians being in the mafia specifically. While there were many Sicilians, there were many Neapolitans, Calabrese(certain parts of calabria in particular seem to be very similar to Sicily due to proximity as the two regions almost border one another) and so on.