Well one thing you can do is proceed to experiential analysis (If you are looking for physical easily visible leaf differences you can probably disregard my post):
First try 5-10 (10 being quite strong) grams with your MAOI of choice, if it is quite active and strong then you have yourself true Diplopterys Cabrerana (Chaliponga).
If no noticeable effects are experienced slowly up the dose and you should start to have effects around 50g with traditional Psychotria Viridis (Chacruna)
Other than that you could use the Latin names I have provided and google images to attempt to differentiate, but in my experience samples can be extremely variable and therefore hard to distinguish definitely.
Use caution though, if you do decide that what you have is Chacruna and proceeed to take ~50g, had you been wrong you will be on a very, very high dose of Chaliponga. (usual dose of Chaliponga is 2 to 15g)
Much love to you.