Nepenthes fusca /nɪˈpɛnθiːz ˈfʌskə/, or the dusky pitcher-plant, is a tropical pitcher plant endemic to Borneo. It is found throughout a wide altitudinal range and is almost always epiphytic in nature, primarily growing in mossy forest. The specific epithet fusca is derived from the Latin word fuscus, meaning 'dark brown' or 'dusky', and refers to the colour of the pitchers. The first known collection of N. fusca was made by Frederik Endert on October 12, 1925, from Mount Kemul in East Kalimantan, at an elevation of 1500 m. It was discovered during an expedition to central Borneo by the Forest Research Institute of Bogor (then known as Buitenzorg), on which Endert also made the only known collection of N. mollis. The N. fusca specimen, designated as Endert 3955, includes male floral material and is deposited at Herbarium Bogoriense (BO), the herbarium of the Bogor Botanical Gardens. Endert wrote about this pitcher plant in a detailed 1927 account of the expedition, although he misidentified it as N. veitchii. Nepenthes fusca was formally described in 1928 by Dutch botanist B. H. Danser in his seminal monograph 'The Nepenthaceae of the Netherlands Indies'. Danser based his description solely on Endert 3955, citing no other specimens. He wrote of N. fusca: Botanist Jan Schlauer has noted differences between the type specimen of N. fusca and Sabah plants referred to this species, even interpreting plants illustrated in Kurata's Nepenthes of Mount Kinabalu as representing N. stenophylla (as distinct from N. fallax). Matthew Jebb does not consider these differences significant enough to merit distinction at the species level. He suggests that the type specimen consists of intermediate lower and upper pitchers as opposed to true forms of either, making them appear atypical. Much of this taxonomic uncertainty stems from the fact that N. fusca has not been recollected from the type locality and many similar plants have been lumped under this taxon. Matthew Jebb and Martin Cheek attempted to resolve this confusion in their 1997 monograph by interpreting N. fusca as a widespread and variable species. Two subspecies of N. fusca have been described, neither of which is presently thought to represent the species: Both were originally coined by J. H. Adam and C. C. Wilcock and subsequently published in Jebb and Cheek's 1997 monograph, 'A skeletal revision of Nepenthes (Nepenthaceae)'. As these names were published without an adequate description, they are both considered nomina nuda. The former is likely based on Chai 35939, a specimen collected from Mount Apo. Schlauer considers it synonymous with N. fallax, a taxon that is in turn considered conspecific with N. stenophylla by most authors.