I haven't been able to do much research on our last name. But, I can give you a little of what I know. You might want to start with doing searches of the original spelling of our last name: Porziuncola (the name of a church in Assisi, Italy), Portiuncula (Latin), or Porzioncula (Latin).
Just out of curiosity, how do you pronounce Porciuncula? I pronounce it POR•SHUN•COO•LA. My parents pronounced two different ways: One being the way I pronounce it and the other being POR•SEE_YUN•COO•LA.
I've spotted the different spelling of our last names in three main countries: ITALY, SPAIN and PORTUGAL. If you do a general search on the internet, BRAZIL is also highlighted. However, Brazilians a decendants of PORTUGAL.
The problem I've been having is connecting how our name travelled to the Philippines, assuming you are filipino, and how our name evolved to Porciuncula.
Keep in touch if you'd like. There aren't many Porciuncula'saround. To tell you honestly, every Porciuncula I come in contact with feels like family to me.