Help ID a plant from Uganda

A friend collected the plant in the rain forest of Uganda, it is not a Peperomia because the inflorescence is complex
It is a tuberous plant, the leaves have a cardboard like texture

 

I am hesitant to propose Piper umbellatum, although the plant does look weird.

 

Sibiryak, after looking in google images for your suggestion, I think the inflorescence of the Uganda plant is different.
Thank you.