"The leading Rhipsalidopsis breeder is ThorŪ by Thoruplund AS, Denmark.

Rhipsalidopsis, which originates from Brazil, is a plant with a long history. It came to Denmark in 1899 and has been highly developed over the years. Rhipsalidopsis is also commonly known as 'Easter Cactus' or 'Spring Cactus'. Thoruplund has produced Rhipsalidopsis since 1974"

From the hybridizer: https://www.greenex.com/flowering/rhipsalidopsis-easter-cactus-by-thor/anett/