First, Welcome!
I was thrown for a moment, looking in my orchid resources... but not an orchid. Google to the rescue, Wittia Amazonica AKA Pseudorhipsalis amazonica . Looks like a really neat plant. So look for it under Pseudorhipsalis. If you don't find it elsewhere, you might inquire at
Andy's Orchids . When I have worked at open houses there, I see quite a few Rhipsalis get purchased, he may have this Pseudorhipsalis as well. (I don't know much about the non-orchids but there are some pretty special and exotic ones there) Won't be on the website, but worth asking about.