Descendants of Cosgarach Cúilfhionn (Fair-Haired) mac Lorcáin

Son of Lorcáin.

Translation of section in An Leabhar Muimhneach on the descendents of Cosgarach mac Lorcáin (page 302):

Twelve sons had Cosgarach, the son of Lorcáin. Eight of them left descendents: Flaithbheartach from whom descend Uí Sheanacháin (from Seanacháin son of Flaithbheartach) ; Conghal, from whom descend the Uí Chnáimhín (from Chnámhín son of Conghaile), Aichear from whom descend the Uí hÓgáin (from Ógáin the son of Aichear); Allathach, from whom descends the Muinntear Allathaigh, Maol Ruanadha from whom descends the Muinntear MhaolRuanadha, Diarmaid, from whom descends the ui Glóiairn (descended from Glóiairn the son of Diarmaid), Aingidh from whom descends the Muinntear Aingeadha, Maine from whom descends the Muinntear Mhaine. Four of his sons have no descendents: MaolSeachloinn, Flann, Cú Mara and Dubh. (on page 236 ALM, Muinnter Uallacháin is also mentioned as a descendent of Cosgarach)

Shanahan

From Irish Ó Seanacháin. Descendents of Seanacháin mac Flaithbheartach mac Cosgarach mac Lorcáin. Scattered throughout Munster by the O'Briens after 1318. Some adopted "Shannon" in their home country Clare. (this information came from whatever source johngrenham.com uses)

Testers:
"Shanahan/75766 - BY7" underneath PH184

Hogan

Situated in Ard Cróine. Descended from Ógáin mac Aichear mac Cosgarach mac Lorcáin. Very numerous. Most famous descendent was Galloping Hogan, a rapparee known for guiding Patrick Sarsfield to blowing up a Williamite siege train in Ballyneety.

Testers:
Many Hogans under BY174767, the son of PH184

Luttrell

American family descended from immigrant James Luttrell born around 1650 probably in Tankardstown, County Meath. He may have been related to the Luttrell family in Luttrelstown. (wikitree: https://www.wikitree.com/wiki/Luttrell-539)

Many Luttrell, Lutrell, Littrel, Litteral, Litrell testers under DC877, the son of BY174767, son of PH184.

It is somewhat possible that this line arose from a Hogan NPE. Given its more closely related to Hogan (both share BY174767) than the one Shanahan tester (simply under PH184, who is hypothetically sharing the most recent common ancestor of Cosgarach), it is likely they are at least descendents of Aicher, Ógain's father. But since the descendents of Ógain are the only descendents mentioned of Aicher, I think it's likely the NPE arises from a Hogan. The structure of the tree itself though would not necessarily be definitive evidence for an NPE in the absense of other information.

The Luttrell family arrived in Ireland in the Middle Ages and were large land owners around Luttrellstown Castle. It can be presumed that at some point from the family's arrival from England, and their descendants departure to America, an NPE with (probably) a Hogan line occured.