Looks like one of the many shades of Orbea variegata. Their stems are a little different then the common Stapelia. Their flowers are between 1 to 3 inches across. Nick named Carrion-flower due to the smell of dead meat rotting.

Thank you for the comment, Stush! That was actually the first one I thought too. But looking closer, several things don't fit. The biggest is the very hairy petal edges. I've seen several species of Orbea that have this, but O. variegata is not one of them. Also, O. variegata does not have the red annullus even in its red forms. Also the shape of the annulus is different here (that could be cultural perhaps). Orbea variegata also doesn't have color forms with that strong red petal edge color. In a O. variegata, the outer corona (the larger star inside the annulus) has distinctly forked tips, this one does not. This one also has a different structure and color pattern to the very inner corona than any Orbea variegata. So I guess I'm fairly certain it's not a match.

Where did you find this Tom? Good chance it's a seedling hybrid.

I got it in a local trade with someone up here in Washington state near the Canadian border. They seemed to grow more basic grocery-store-style plants, so not where I'd expect to find a rare hybrid; but that is certainly a possibility.

I purchased seed on Ebay a while ago and ended up with about 50 plants which were from open pollinated flowers so it happens a lot.

Tom, in case you don't get a satisfactory ID here, and you're on FB, there's an Asclepidaceae group there (focusing on the succulent members of the Family) that's quite good at naming them.

'Miles To Go' has tons of great stuff. I used to purchase my Asclepiad from them with good results. I think but not sure that Miles is retired and there are new owners. Still sells same stuff. I gave all mine away but found one unnamed one that I still have growing.

Thank you all! A quick check at WCSP says that correct name for Orbea speciosa you mentioned is Orbea mcloughlinii. Looks like the name was accepted by all the serious authors back about 2002, but I see most online still have their plants labeled as speciosa.