This is indeed a bit confusing. Rosa xanthina Hook.f. is not the Rose we generally know as Rosa xanthina Lindl. In Curtis's Botanical Magazine of July 1, 1899 there was a description of a "Rosa xanthina" which was pictured and named as the latter with the statement:
"The specific name Ecae is derived from the initials of Mrs. Aitchison's name, given before the plant was identified with Lindley's Rosa xanthina. The specimen figured is from a plant raised at the Royal Gardens from seed sent by Dr. Aitchison in 1880."

However, it was later apparently concluded that this description was not of R. xanthina Lindl. as claimed, but a different species. In that case, the name Rosa ecae Aitch. which had already been published 1880 had again priority and was valid. I have modified the note to "distinct species" only.