Recently most of our Diastema sp. (fam: Gesneriaceae) have been re-identified as Diastema incisum, a species considered Critically Endangered. The story of this species is very interesting. Apparently it was described 200 years ago and was then forgotten. However ... since it was re-discovered and considering that it's not as rare as thought, it will probably lose it's status as Critically Endangered.

John Clark explained this in a little more details in this post:
https://www.instagram.com/p/Cvj82y0MkHz/?img_index=1