I'm fairly new to the Ultra scene but my definition is (and it is the same for marathons):
If I enter an official race and complete it, I have run an Ultra.
If I do my own run over 26.2 miles, then I run an Ultra Distance. I ran the Sedona Marathon with a 1 mile jog to the start line (full discloser, I walked the last 10 miles because of ITBS). I did not count this as an Ultra or Ultra distance even though the total was over 26.2. Last fall I ran 27 miles in mud, snow, technical trail, and big elevation gain. I did count this as a Ultra distance. Once in a while, I pat myself on the back for more extreme conditions.
Either way, I would consider myself an Ultra runner (even though most Ultras contain a large portion of hiking, walking, sitting in a chair at an aid station
, etc.), but I was hesitant to call myself that until I did an official Ultra.
Marathon or Ultra on the race you are considering? Since it has Marathon in the title, I would call the race a Marathon and you an Ultra runner after you complete it (or before, because I bet you are going to want to do an Ultra distance before the race), but no big deal either way, it looks like an incredible run.