http://www.newadvent.org/cathen/13180a.htm
There are twelve Irish saints bearing the name of Ronan commemorated in
the "Martyrology of Donegal"; of these the most celebrated are:
St. Ronan of Ulster, brother of St. Carnech, and grandson of Loarn, d.
11 January, 535;
St. Ronan, son of Berach, a disciple of the great St. Fechin of Fore. He
became first Abbot of Drumshallon, and d. 18 November, 665.
St. Ronan Fionn is honoured as patron of Lan Ronan (Kelminiog) in
Iveagh. His feast is celebrated on 22 May, both in Ireland and Scotland.
St. Ronan of Iona is explicitly referred to by St. Bede as one of the
protagonists of the Roman custom of celebrating Easter as against the
Irish tradition, and he had a warm controversy on the subject with his
countryman St. Finan, Bishop of Lindisfarne, 660. This controversy was
ended at the Synod of Whitby, in 664, when St. Ronan's views were
upheld.
St. Ronan of Lismore
was a distinguished successor of St.
Carthage, and several Munster churches were built in his honour. His
feast is celebrated on 9 February 763.
Another saint of this name is
best known by the ruined church of Kilronan, Co. Roscommon, where
Turlogh O'Carolan and Bishop O'Rourke are buried.