"Nepenthes muluensis" × "N. tentaculata" was described as "N. × sarawakiensis" in 1993 by J. H. Adam, C. C. Wilcock, and M. D. Swaine. The authors distinguished the taxon from "N. muluensis" on the basis of its branched spur and the presence of fringe hairs on the top of the lid. They also compared the distribution of phenolic compounds in the leaves of "N. muluensis" and the hybrid, although they did so without specifying the number of plants studied or the number of repetitions performed. As a result, doubts have been raised over the existence of this hybrid. Charles Clarke writes that the authors described "N. × sarawakiensis" "in such a way that their work cannot be easily repeated". Although this natural hybrid is likely to exist, it is possible that "N. × sarawakiensis" was described based on specimens of "N. muluensis" with lower pitchers.