Ó Maoildeirg
Ó MAOILDEIRG—I—O Molderge, Mulderg, Mulderrig, Reid, (Reddington, Ruthledge); 'descendant of Maoldearg' (the red chief), or very probably a corruption of the old surname Ó Maoilghiric, which see; an old surname in Donegal, whence it has spread into Mayo, where it is strangely anglicised Reddington and Ruthledge. Reid (for Red) is a translation.
Alphabetical Index to Irish Surnames