My surname is Sena my family is from Italy. My great-grandfather LUIGI SENA hailed from a tiny town in Italy known as San Angelo d'Lombardi which is in the Avelino providence.
He had 9 children, including my grandfather, VICTOR SENA. My grandfather always said the family was from Naples, just to simplify, instead of always having to explain where Avelino was (which is just east of Naples).
I have researched my surname to my great-great-grandfather, PASQUALE SENA. My research discovered that 60% of all the names in the small town of S. Angelo d'Lombardi have the last name of SENA, and that the name can be traced in Italy (S.Angelo), Spain and Portugal. One varriation of the name includes a double "N" but I found that to be the case mostly with the Spanish version.
In Italy the surname SENA definately originates from S. Angelo d'Lombardi, as no other city or town has this large concentracion of SENAs.
I hope this information helps. Please feel free to contact me via e-mail at MSENA@KAYEGROUP.COM