I am not sure if there is a key, but I do know that Florian Werner (https://www.researchgate.net/profile/Florian-Werner-2) spent quite a bit of time working on epiphytes in that area so I'd recommend to get in touch with him.

There are different data material will you find out about it to identify epiphytes but this Research article also will to you review to this article

"Ecohydrological Observatories in the Tropical Andes of Southern Ecuador"

Hi Lukas: Luis Baquero (https://www.researchgate.net/profile/Luis-Baquero) is an Ecuadorian expert in orchids. He could help you.

Hi Lukas,

take this one for the Aroids:

https://fieldguides.fieldmuseum.org/guides/guide/629

For Ericaceae there is another one:

https://fieldguides.fieldmuseum.org/guides/guide/630

But so far nothing for Orchids or Bromeliads.

Saludos

Jürgen

Hello, I have some species identified in the Loja Herbarium (photo and scientific name) from a study of epiphytes that I carried out in the Andean montane forests of Azuay three years ago. Let me know if this works for you.