I have that same Iris Mona. Boy what a chore it was trying to separate it. I wanted to give my daughter some because it had formed such a large clump. It took me almost an hour to separate it. Had to cut through the clump with a knife and then I used to pitchfork. I was finally able to get some out of the ground. Those plants really dig in. It's like cutting through cement. I have another clump to separate and I am dreading it.
