There's good reason for your confusion. There is a man-made hybrid species named Dombeya x seminole. There was an entry for it in our database, but I deleted it because we don't list hybrid taxa unless they're spontaneous crosses, occurring in the wild. Dombeya acutangula probably was one of the species involved in the cross. Some sites list it as Dombeya burgessiae 'Seminole,' so that probably is the other species involved.
I think the best solution is to enter it as a cultivar, with no species listed. Here's an entry for it:
Tropical Rose Hydrangea (Dombeya 'Seminole')
