Here is what the late, great, Christine Burton has to say about this plant from her P.S. The Hoyan:
“Many of you think you have this species but you don’t. You may have purchased one from one of the following sources:
Liddle Nursery in Mareeba, Qlds., Australia, as Hoya minahassae (IML-1863). This is NOT Hoya minahassae.
Paul Shirley of the Netherlands, as GPS-8875 or GPS-8816. It is NOT Hoya minahassae.
Van Donkelaar of the Netherlands as IPPS-8875 or IPPS-8816. It is NOT Hoya minahassae.
You may have seen Kleijn and van Donkelaar’s publication, Taxonomy and Ecology of the Genus Hoya in Blumea 46(3):2001 with your plant plainly illustrated so you think your plant has to be Hoya minahassae. The only things proved here are that Kleijn and van Donkelaar hadn’t done their homework and the editor of Blumea hadn’t either.
Schlechter’s holotype specimen is extant and in excellent condition. I have seen it. I had it here at Fernbank for 3 months and viewed it and all of its flower parts under the lens of a high powered microscope. Besides that, Schlechter drew pictures of all the flower parts and pasted the pictures on his holotype specimen.
If you’d like to see an excellent, well illustrated article comparing this hoya with the true Hoya minahassae, you can find one in the Swedish publication, Hoyatelegrafen, #3 (2008). The text is written in Swedish but you don’t need to read the text to know what is said. The illustrations speak for themselves. They prove that not one single part of the plant, GPS/IPPS-8875, GPS/IPPS-8816 and IML-1863, matches. These numbers do NOT represent Hoya minahassae. What is it? I’m sorry, I don’t know, yet. Please keep the IML-number on your plant, until someone learns what it is.
I think that what she is saying is that the true Hoya minahassae described by Schlechter earlier does not match up to any of the plants that we now keep labeled Hoya minahassae. For now, I will have to keep that name, as that is what everyone else is calling it, until, and if this ever gets remedied.