In their 1997 monograph, "A skeletal revision of "Nepenthes" (Nepenthaceae)", Matthew Jebb and Martin Cheek tentatively referred specimens collected from Bukit Bakar, near Macang, Kelantan, to "N. sanguinea". These were "Stone & Chin 15238", deposited at Universiti Kebangsaan Malaysia near Kuala Lumpur (KLU), and "Shah & Shukor 3168", also held at KLU as well as the Forest Research Institute of Malaysia in Kepong (KEP). They noted that the plants exhibited some unusual morphological features, such as larger leaves and , almost leaf bases, suggesting that they might represent an as-yet undescribed taxon.