The Ithell clanEdit
Not very much is known about the Ithell Clan, and the only known time when they are mentioned in RuneScape is in the Crystal of seren book, given to a player by Ilfeen: it is said that the Ithell Clan are famous for Crystal chanters. Most crystal chanters come from this clan, while very few come from any other of the seven families, which could significantly weaken the Iorwerth Clan, as they would have a considerably low number of the much needed chanters to make equipment, putting them at a disadvantage in times of war.
There are no confirmed members of the Ithell Clan; however, it is likely that Ilfeen and maybe Eluned are part of the Ithell clan, due to the fact that they are both crystal chanters. Arianwyn is also a possibility, but there hasn't been any confirmation on this.