 The population currently listed as "P. p. wurmbii" may be closer to the Sumatran orangutan ("P. abelii") than to the Bornean orangutan.If this is confirmed, "P. abelii" would be a subspecies of "P. wurmbii" (Tiedeman, 1808).In addition, the type locality of "P. pygmaeus" has not been established beyond doubt; it may be from the population currently listed as "P. wurmbii" (in which case "P. wurmbii" would be a junior synonym of "P. pygmaeus", while one of the names currently considered a junior synonym of "P. pygmaeus" would take precedence for the taxon in Sarawak and northern West Kalimantan).