This is the most difficult one to find in cultivation. R. pacheco-leonis ssp. catenulata is often mislabeled as R. pacheco-leonis ssp. pacheco-leonis. It does not help that there are varying clones of ssp. catenulata where the chaining can be somewhat more and less prominent as well as thicker and thinner branches, leading growers to believe they are distinct species.
Both subspecies of R. pacheco-leonis have pinkish/red blooms.
This plant does not look like a miniature version of R. paradoxa ssp. paradoxa. It looks like a miniature version of R. paradoxa ssp. septentrionalis, which has a different branching habit than ssp. paradoxa.
The chaining on this species is also not as prominent as most of the other chaining species, it generally has more angles. It also has 2 distinct types of growth as seen in the photographs from Uhlig Kakteen, leading it to commonly be confused with R. dissimilis, however, the flowers of these two species are distinctly different. Uhlig Kakteen is the only commercial source I have found for this species where it is correct. Here are other pictures where this species is correctly identified: EPIG Facebook group post 1, EPIG Facebook group post 2, Facebook gallery, rhipsalis.eu .
My pictures are of cuttings from Uhlig Kakteen freshly arrived. They are desiccated from their journey so the chaining is more prominent than it would be otherwise. These are cuttings as well so the mature habit is not as pictured, however you can see from the cuttings the branching growth habit similar to that of R. paradoxa ssp. septentrionalis.
There is also a good picture of the branching habit of this species in the book The New Cactus Lexicon – Illustrations, the book is out of print so it can be difficult to find and expensive. I ordered mine from Kakteen-Haage.