Subsequent authors realised that Burbidge's hybrid hypothesis was erroneous when it became apparent that "N. sanguinea" is altogether absent from Borneo. In 1884, Eduard August von Regel published a short article on "N. northiana" in the journal "Gartenflora". Günther Beck von Mannagetta und Lerchenau described "N. spuria" in his 1895 monograph, "Die Gattung "Nepenthes"". This taxon is a "nomen illegitimum" and is now considered synonymous with "N. northiana". In his "Handleiding tot de kennis der flora van Nederlandsch Indië" of 1900, Jacob Gijsbert Boerlage mentioned a certain "N. nordtiana". This name is considered a "sphalma typographicum" (misprint) of "N. northiana".