The species was mentioned as an undescribed taxon in Charles Clarke's 2001 monograph, Nepenthes of Sumatra and Peninsular Malaysia, under the name Nepenthes species B. Clarke considered it to be most closely allied to N. singalana, writing that [f]urther research is required to determine whether or not this is simply an unusual variety of N. singalana, or whether it warrants description as a distinct species. Flowering-size specimens of N. izumiae, identified as N. singalana from Mount Talakmau, were already in cultivation before the species was formally published.