Cruimthear Mac Carthaigh Wikipedia
Cruimthear Mac Carthaigh (the presbyter Mac Carrthaigh), fl. c. 550.
In the genealogies, Mac Carthaigh - his forename, not his surname - is stated as been a native of Conmaícne Cúl Toland in what is now along the County Galway - County Mayo. Thus he was from the same tribal group of Jarlath of Tuam. This branch of the Conmaicne were said to converge, or descend, from Cumhscraidh mac Céacht, who in turn was a descendant of Lugaid mac Con. It is unclear which church he was attached to.