In the process of clipping the fictional and legendary profiles off the Irish tree, I was looking at the profile for Dobbchad mac Murchad. The name of his wife seemed odd to me, so I looked him up on Medlands, where I found that the name of his wife is unknown.
So I clipped her off. (Here she is: Orlaith ingen O'Braenain)
But this has been quite upsetting to at least one user, so I went looking to see what I could find about Donnchad and Orlaith, to see how they had gotten connected.
And I found that Orlaith is mentioned as the mother of Diarmat mac Murchada in Wikipedia. Here is that page — look on the side bar for the connection, though there are no links, alas: https://en.wikipedia.org/wiki/Diarmait_Mac_Murchada
Here is Medlands, on Donnchad: http://fmg.ac/Projects/MedLands/IRELAND.htm#DonchadLeinsterdied1115A
Now, Wikipedia gives no references for the connection of Diarmait to Donnchad and Orlaith. At the end of the page it gives sources for genealogy, which include the Annals of the Four Masters and O’Hart.
Medlands quotes the Annals of Tigernach for the information on Donnchad, and several sources for the information on Diarmait, one of which calls him “rex filius Murcath,” which wouldn’t be confusing except that Medlands also says that Donnchad had onk6 one child, his son Enna, and that Enna was the father of Donnchad.
What’s going on, as far as I can tell, is that we know of Enna’s existence from the Annals of Tigernach, and the chronology simply does not work if Diarmaid is the son of Murchad directly. There has to be another generation in there.
So.
The genealogical sources in Wikipedia that look relevant are the Annals of the Four Masters and O’Hart. The Annals of the Four Masters mentions Donnchad’s death in 1115:but that’s it. Here is a translation: https://celt.ucc.ie/published/T100005B/
Which leaves us with O’Hart, whom we know to have invented connections when he wanted them and they didn’t exist.
Unless someone has more compelling evidence, I think that we should leave Donnchad without a wife. She is neither the Alanna’s of the Four Masters nor the Annals of Tigernach.
Now, I’m less thoroughly convinced that we need to take Enna’s brothers off as children of Donnchad and give them to Enna, but I certainly think it would make sense.
It wouldn’t affect the lines of the genealogy, since Enna’s wife is also unknown, which means it is a less important issue that the question of did Donnchad have a wife.