Yes, it is spelled Ponthieu in France. I think that some of the Ponthieus who came to La. either added the x themselves or some govt. official added the x because many of the Acadians had an x in their name. However, it is my understanding that the Ponthieus of Avoyelles did not come via Canada, but directly from France. By the way, I was in Paris several years ago and found a street named Ponthieu. There was a Ponthieu hotel and bar on this street. As I recall, it is no far from the Arc de Triomphe.