Epiphytic shrub or climber in canopy, less usually terrestrial, stems to 3 m tall. Leaves petiolate, coriaceous; Fruits with valves 18-22(-39) by 3-3.2 mm. Seeds filiform, 9.5-11.5(-20) by 0.2-0.4 mm.
Asia-Tropical:, Borneo ‒ present (Brunei ‒ present, Kalimantan ‒ present, Sabah ‒ present, Sarawak ‒ present)
Borneo: Sarawak, Sabah, Brunei, and Kalimantan.
3. Kostermans 21495 (K, L) represents an extreme variant of N. fusca, approaching N. eymae in appearance. We also include in N. fusca the recently described N. curtisii subsp. zakriana on the basis of the photographs that accompany the protologue (N. curtisii is a synonym of N. maxima). 4. Nepenthes fusca subsp. apoensis J.H. Adam & Wilcock, ined., based on Chai 35939, belongs to N. stenophylla by virtue of its sheathing leaf bases, rounded lids and indumentum. 1 Nepenthes fusca is immediately distinguished from the closely related Bornean species N. faizaliana, N. pilosa, N. stenophylla, and N. veitchii by the lids of the upper pitchers which are narrowly triangular and have involute margins. In lower and mid-pitchers the lids are more ovate, and often flat, and it is only in the upper pitchers that the species-specific characters are constantly found. The inflorescence of this species is also smaller and more delicate than the foregoing species. Danser in described N. fusca from the type specimen alone, and although upper pitchers are present on the two duplicates at Bogor, none have lids. Fortunately the isotypes at K and L have upper pitchers with the characteristic lid. 2. The glandular crest-like appendage at the base of the lid is always developed in this species, but the apical appendage may or may not be developed, and then usually only in upper pitchers. Whilst it was once argued that the presence of an apical appendage characterises N. maxima, we view that species as a closely related taxon distinguished from N. fusca by a broadly ovate lid. Nepenthes maxima occurs from Sulawesi to New Guinea, whilst N. fusca is restricted to Borneo.