The O'Mahonys continue to be very successful, including in their genetic genealogy research. The O'Mahony Society provides a journal and other research resources.
According to historian Jeremiah O'Mahony, there were several sub-septs. Clan Ceitherne (Kearney or Carney) settled around Poulerick and around Crookstown, but were encroached upon by McSweeneys and McCarthys.
The same historican cites Clan Conogher with territory in the eastern part of Kilmichael and part of Kilmurry.
Ibh Flah Luadh held several small ploughlands in the western part of Kilmichael.
A branch that settled in Kilnaglory were related to a branch that settled in County Kerry.
Examples of O Mahony secondary names are: Ban, Baid, Meirgeach, Scimillihane. Keane & Kearney [all found in the RC parish of Barryroe], Drohid, Feigh, Glacy & Kenoe (Mizen Peninsula). Canniffe are also Mahonys, being descended from the black-haired Cian - Ciam Dubh.
The Caine/Keane (Cian) surname may have its origin in O'Mahony Cian. (See S.S. Nicknames). This might be written as Cane, Cain(e), Cian, Kane, or Kean(e).
Carney or Kearney could be Ó Mathúna Ceithearnaigh.
Other forms may include Mahon, Mathews, White [from Ó Mathúna Bán].
Ó Donovan, Peadar. Story of the O'Mahony Clans and their Castles. Southern Star. October 24, 1981.
Ó Mahony, Jeremiah. West Cork and its Story. Southern Star. May 28, 1949.
Ó Mathúna, Padraig. Forms of The Name. The Ó Mahony Journal. No. 14, 1990. Pages 23 - 25.
Ó Halloran, W. Lords of the Soil of West Cork. O'Mahonys. Early Irish History and Antiquities and the History of West Cork.
Hickey, Nora. Tracing the O'Mahonys of the Diaspora: Research in Ireland. Ó Mahony Society.