As far as I've read it's Brassocattleya x Cattleytonia - how did they ever get that to be "Stellamizutaara"?!?!
However according to RHS your specific plant is Brassavola nodosa x Cattleytonia Keith Roth. The latter is Cattleya bicolor x Broughtonia sanguinea. So that would be the entire family tree of your plant
The flowers are lovely btw, very delicate - almost pastel and translucent - it probably got that from the Ctna Keith Roth..