Nepenthes fusca , 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.
Botanical history 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 1,500 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.[note a] 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[b] 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:
This new species is, together with N. Veitchii and N. stenophylla, very nearly related to N. maxima, but can not be confounded with any of these species. According to Endert it grew in the forest on a narrow, stony mountain ridge covered with humus, and was not rare.
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).[c] 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.
Subspecies Two subspecies of N. fusca have been described, neither of which is presently thought to represent the species:
Nepenthes fusca subsp. apoensis J.H.Adam & Wilcock ex Jebb & Cheek (1997) nom.nud. [=N. stenophylla] Nepenthes fusca subsp. kostermansiana J.H.Adam & Wilcock ex Jebb & Cheek (1997) nom.nud. [=N. epiphytica] 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. Nepenthes fusca subsp. kostermansiana was named from the herbarium material Kostermans 21495, which was collected by André Joseph Guillaume Henri Kostermans on October 25, 1963, at 1000 m altitude along the Kelai River on Mount Nyapa (Njapa), Berau Regency, East Kalimantan. It is deposited at the National Herbarium of the Netherlands in Leiden. This taxon was initially thought to fall within the variability of N. fusca, but in 2011 it was described as a distinct species, N. epiphytica, with Kostermans 21495 designated as its holotype.
Nepenthes maxima
Nepenthes maxima, a species native to Sulawesi, New Guinea, and the Maluku Islands, was once thought to extend to Borneo as well. Some authors even wrote that it was widespread on the island. This confusion stemmed from the likeness of N. fusca and N. maxima, and from apparently mislabelled seeds collected by Charles Curtis. Curtis was not meticulous in recording where he located individual plants; although it was originally believed that he collected N. curtisii (now considered synonymous with N. maxima) in Borneo, botanist Charles Clarke points out that he also visited Sulawesi on the same trip, and N. maxima is common there. Matthew Jebb and Martin Cheek resolved this confusion in their 1997 monograph by referring a number of Bornean plants identified as N. maxima to N. fusca, thereby excluding the former from the island.
Nepenthes zakriana In 1996, J. H. Adam and C. C. Wilcock described Nepenthes curtisii subsp. zakriana.[d] Ten years later, Adam and Hafiza A. Hamid elevated it to species status as Nepenthes zakriana (, not /ˌzækriˈænə/). The authors described the taxon as a Sabah endemic growing at elevations of 1,200 to 1,500 m. Adam and Hafiza wrote that N. zakriana "consistently differed from Nepenthes fusca by prominent raised midribs, extended beyond apex forming an apical glandular appendages on lower lid surface of both upper and lower pitchers; and basal half portion of the midrib developed in nail-shaped glandular crest". However, a number of authors soon voiced their doubts as to whether N. zakriana merited species status and in Pitcher Plants of Borneo by Anthea Phillipps, Anthony Lamb, and Ch'ien Lee, these features were considered to fall within the natural variability of N. fusca. The taxon was reinstated in 2019 based on isolated distributions and morphology, and the previous synonymy was attributed to the frequent hybridization between members of Nepenthes.
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