I have a dark clone of Nepenthes truncata 'Pasian' for trade, while it isnt "Black" it is a dark brown color. I discovered it in a batch of seedgrown Nepenthes truncata 'Pasian' that originated from BE. Please PM me with offers.
It does not have pitchers currently due to the shortened photoperiod and a recent repotting, but here is a photo from when it did.
And a photo of it now.