The McGillicuddy DNA Project is open to all who are interested in working together to find their common heritage through sharing of information and DNA testing. All variant spellings are welcome. It is a surname connected to the O'Sullivans and fairly recent in origin. Irish: Mac Giolla Chuda or Mac Giolla Mhochuda meaning "son of the servant of St. Mochuda". The female unmarried variation of the name in Irish is Nic Giolla Chuda, and the married female version of the name is Mhic Ghiolla Chuda. Ref https://en.wikipedia.org/wiki/McGillicuddy