The Mustang and Muscadine grapes are from the same family and genus but are different species. The Muscadine also grows wild all over the south.
We may well have Muscadine here. There are huge vines on many trees here. The winery at Tow, Tx was started by a guy visiting from Ca. He saw how great the grapes were growing near Lake Buchanan, bought some land and grafted Ca grapes onto the existing vines. He had gold medal wines in three years.