Horribly misleading title and text. "Besides vapor, ice and liquid, a fourth form of water may exist." At least 15 crystalline phases of water exist, including Ice IX. I think this is the relevant paper
http://pubs.acs.org/doi/abs/10.1021/jp2051867 but it's behind the ACS paywall. In any case, it's based on computer simulations using the TIP5P water model, and not experiment.