Nepenthes dubia certainly is one of the least well known species of the genus. It is only recorded from Gunung Talakmau in West Sumatra though there is a lot of confusion with a hybrid between N. inermis and N. talangensis which is found on Gunung Talang. This hybrid resembles it a little. Note the lid of the pitcher which points backwards and the flat peristome. Interestingly N. dubia grows exclusively as an epiphyte.
Copyright by Andreas Wistuba. The photograph may be downloaded for private use and may be used by the ICPS. The photograph may not be used commercially or for publications without permission by Andreas Wistuba (firstname.lastname@example.org)