[3] Nepenthes pilosa was formally described[note a] in 1928 by Dutch botanist B. H. Danser in his seminal monograph "The Nepenthaceae of the Netherlands Indies".

This specimen was collected by Eric Mjöberg between October and December 1925, from Bukit Batu Tiban at an altitude of 1700 m. Danser wrote of Mjöberg 46:[2] "It is only one leaf with upper pitcher, and an inflorescence not certainly belonging to the same plant; the pitcher is not congruent with that of number Amdjah 491 and this is the reason I have not completed the description with that of the male inflorescence.

One example of this is the treatment of N. chaniana by Bertram Evelyn Smythies in 1965,[7] in the proceedings of the UNESCO Humid Tropics Symposium, which was held in Kuching two years earlier.

also notes that the upper pitcher on the type is unusual [...]"Despite this, Matthew Jebb and Martin Cheek did not distinguish the East Malaysian plants from N. pilosa in their monograph published the same year.

[10] Similarly, in Pitcher-Plants of Borneo (1996), Anthea Phillipps and Anthony Lamb treated plants from Mount Alab, Crocker Range, as N. pilosa, following the interpretation of J. R. Turnbull and A. T. Middleton in an unpublished mimeograph report[11] from 1981.

[3] Although he treated plants from East Malaysia as N. pilosa in his 1997 monograph, Charles Clarke doubted their conspecificity.

[3] In July 2006, Clarke revisited wild populations of N. pilosa on Bukit Batu Lesung to confirm its status as a distinct species.

It is grooved and bears a pair of narrow wings that form an amplexicaul sheath around the stem and are decurrent for up to 2.5 cm, terminating abruptly in a rounded base.

It bears a series of ribs spaced 1⁄3 to 1⁄4 mm apart, which terminate in short teeth that are barely longer than they are broad.

Virtually the entire inner surface of the pitcher is glandular, having very small overarched glands at a density of 2000 to 2500 per square centimetre.

Small round glands are scattered throughout the lower surface of the lid and a prominent hook-like crest is present near the base.

[2] Herbarium specimens dry to a reddish-brown colour on the stem and the underside of the leaves, while the upper surface of the lamina is typically fallow.

A population of approximately 200 plants has been found growing at an elevation of around 1600[12] or 1700 m.[3][4] Nepenthes pilosa is classified as Data Deficient on the 2014 IUCN Red List of Threatened Species.

[5][6] Nepenthes glandulifera has a similarly extensive indumentum, but lacks a well-developed lid appendage and bears many prominent extrafloral nectaries.

[3] Folia mediocria petiolata, lamina lanceolata, nervis longitudinalibus utrinque 4-5, vagina caulem fere totum amplectente; ascidia rosularum ignota; ascidia inferiora mediocria, in parte inferiore oviformia, os versus cylindrica, costis 2 prominentibus ad os appendicibus 2 ramosis; peristomio operculum versus acuto, applanato, 4-7 mm lato, costis dentibusque 1/3-1/4 mm distantibus, dentibus vix longioribus quam latis; operculo suborbiculari subcordato, facie inferiore pilis parcis patentibus, prope basin carinato; ascidia superiora, magna, ample infundibuliformia, costis 2 paulum prominentibus, peristomio in collum distinctum elongato, applanato, c. 12 mm lato, costis c. 1/3 mm distantibus, dentibus brevissimis, operculo orbiculari subcordato, facie inferiore pilis parcis patentibus et prope basin appendice lateraliter applanato; inflorescentia ignota; indumentum in omnibus partibus longe villosum, foliorum pagina superiore excepta.