Re: more Sardina'a
It seems that could be different branches of "Sardina". In Spanish, Sardina is a fish, and as such, it could have been one of the surnames impossed when the Jewish and Arabs were converted to Chistianism (something more or less like when the Irish received surnames taken from workers -like Taylor- or colours -like Brown-). In Italy, it could be different, as could derive from Sardinia (the island). I don't know what Sardina means in Italian, but if it means also the fish, might be similar to Spanish case.