Wow!!! That is beautiful. I currently only have debile, but have been keeping my eyes open for other species. After seeing the petiolare I am going to start actively looking for more species.
You said that it likes humidity, I have found the same with the debile. I had no place to put one of my divisions, so I put it in a tray that had some cuttings and a humidity dome. The leaves became much brighter and fuller, I now keep most of my debile in either my greenhouse of under humidity domes. I think they like it much better, however they do not flower as vigorously in the humidity.
Thanks for a great thread.