Horticulturally, they're both ecuadorense. They're just different sizes of the same species. It happens. The 'Si' clone is particularly miniature; that's all. {For example: Check out the local population of Dandelions. Some are very tiny and some are giant. They are all the same species and interbreed constantly.} However, technically, ecuadorense does not really exist. All the small-ish plants with flowers like the ones pictured are pearcei. The ones we commonly call pearcei are much larger and the flower petals have more ruffling and less significant "eyebrows". Those are actually the product of natural interbreeding between pearcei (what we call ecuadorense) and boisserianum. So, in realiity, there is boisserianum, pearcei and a natural hybrid between the two. But, horticulturally, we refer to boisserianum as boisserianum; we refer to the natural hybrid involving boisserianum and pearcei (large plants), as just pearcei; and we refer to the pure species pearcei (mini plants), as ecuadorense.
This naming mess has come into being because for a short time, taxonomists recognised the natural hybrid (big plants), as pure pearcei and the pure pearcei (mini plants), as ecuadorense.....as did the RHS hybrid registrar. Then, they both changed their minds; but, many of the hobbyists did not change their tags. Now, we have a situation where some hobbyists believe that we have boisserianum, pearcei and ecuadorense (3 distinct species) and the natural hybrid between boisserianum x pearcei which is often called Amazonica, or x amazonica. Then, we have the hobbyists who believe the current thinking (by taxonomists and the RHS); that there are only two species, boisserianum and pearcei. Then, there are people like me who, while I believe that there are only two species (boisserianum and pearcei), I use the name ecuadorense as well (in a Horticultural context), simply so that my fellow horticulturalists will know which plant I'm refering to. If I say "pearcei, you don't know if I'm talking about the big one that is the natural hybrid or the little one that is the true pearcei and which is often refered to as ecuadorense. However, if I refer to ecuadorsense, you know that I'm only refering to the miniature sized, true species - pearcei.
However, if you exhibit and want to win anything, you'd better not label your miniature true pearcei plants as just pearcei. That's because they will be compared to the much larger plants that were awarded as pearcie; but, which are actually the natural hybrid with boisserianum. The natural hybrid looks very much like a pure pearcei; but, on steroids. The little plants that are pure pearcie just cannot compete against that. However, if you label them ecuadorense, or pearcei var. ecuadorense, the judges will only compare them to other true pearcei's with the miniature growth habit.
