No, and they aren't the same as muscadine, either, though I've heard of them in the region.

http://palatepress.com/2010/06/wine/wine-indigenous-american-grape-varieties-a-primer/

Of the six native species that had been growing in North America long before European settlers arrived, some may sound more familiar than others: rotundifolia (muscadine), aestivalis (summer grape), riparia (frost grape), labrusca (fox grape), mustangensis (Mustang grape), and rupestris (sand grape). Over the last hundred years some interest has been given to this rowdy and uncouth bunch of American species. While these grapes are not as widely cultivated or commercialized as vinifera varieties, they do show potential for making enjoyable wines and deserve to be recognized.

The author of the article later dismisses our little Texas grape:

Vitis mustangensis has little to no redeeming commercial qualities. Limited in habitat to Texas, Oklahoma, and parts of Louisiana the mustang grape is highly acidic and bitter in taste. Simply handling the grapes can irritate the skin.

The bit about irritating the skin is true. The first time I picked them it was with bare hands and my hands really smarted after a while. I wear vinyl gloves when I work with them now. The remarkable thing about these grapes with their big seeds and thick tough skins is that they still manage to produce a wonderful rich dark pink/red juice and it's perfect for a sweet/tart jelly. If you've ever tasted tamarind or tamarindo, they are sweet and tart in the same way.

I like the jelly on toast, on baking powder biscuits, and I often will heat some in a small custard cup in the microwave and use it as syrup over pancakes. I think you could use it in place of cranberry sauce in a pinch.