Matthew Jebb
In 1986, "N. sumatrana" was again recognised as a distinct species by Rusjdi Tamin and Mitsuru Hotta, who noted significant differences between it and "N. treubiana". Matthew Jebb also treated "N. sumatrana" separately in his 1991 monograph, "An account of "Nepenthes" in New Guinea", as did Joachim Nerz and Andreas Wistuba in 1994, when they described the closely related "N. longifolia". "Nepenthes sumatrana" was formally restored in Matthew Jebb and Martin Cheek's 1997 revision, "A skeletal revision of "Nepenthes" (Nepenthaceae)", although the authors sunk "N. longifolia" in synonymy with "N. sumatrana". This latter decision was reversed by Charles Clarke in his 2001 work, "Nepenthes of Sumatra and Peninsular Malaysia".