No, they don't. A fundamentalist Mormon would be someone who follows the current fundamental doctrine and the living Prophet. A fundamentalist Mormon would not practice polygamy and would, in fact, be excommunicated and wouldn't be able to call himself a Mormon any longer. You might call him a fundamentalist polygamist or something like that, but Mormon would not be an appropriate label.
This is the same stuff that gets sent to the media, illustrating how the LDS organization would like (respectfully, of course) these 'people' be described in the print or TV-radio.