Nepenthes villosa is characterised by its highly developed and intricate peristome, which distinguishes it from the closely related N. edwardsiana and N.

[6] The species was first collected in 1858 by Hugh Low when he made his second ascent of Mount Kinabalu together with Spenser St.

[11] B. H. Danser treated N. edwardsiana in synonymy with N. villosa in his seminal monograph "The Nepenthaceae of the Netherlands Indies", published in 1928.

[3] In Letts Guide to Carnivorous Plants of the World, published in 1992, a specimen of the natural hybrid N. × kinabaluensis (N. rajah × N. villosa) is labeled as N.

[14] In 2004, professional horticulturist Robert Sacilotto published a summary of measured tolerances of six highland Nepenthes species, including N. villosa, based on experiments conducted between 1996 and 2001.

[16] Nepenthes villosa is a weak climber, rarely exceeding 60 cm (24 in) in height,[4] although the stem may grow to 8 m (26 ft) in length and 10 mm (0.4 in) in diameter.

A pair of fringed wings (≤15 mm wide) runs down the front of the pitcher, although it may be reduced to ribs in aerial traps.

[5][20][21] On Mount Kinabalu, N. villosa is common along the Mesilau Trail (between Pondok Magnolia and the meeting point with the old summit trail) and almost all the way up to the Laban Rata rest house;[22] a particularly large population has been reported at around 3047 m.[23] On Mount Tambuyukon, an altitudinal inversion has been noted, whereby N. villosa is more common at much lower elevations of 1600–1900 m, being replaced by N. rajah towards the summit.

[20] The exposed, uppermost slopes of Mount Tambuyukon can become very hot during the day and this might explain the inability of N. villosa to colonise them.

Clarke writes that N. villosa "has a secure future", although he adds that climbers have had a significant impact on populations of the species growing along the summit trail, with the number of plants having declined in recent years.

Joseph Dalton Hooker, who described both N. edwardsiana and N. villosa, noted the similarity between the two species as follows:[10] This most remarkable plant [N. villosa] resembles that of edwardsiana in so many respects, especially in the size, form and disposition of the distant lamellae of the mouth, that I am inclined to suspect that it may be produced by young plants of that species, before it arrives at a stage when the pitchers have elongated necks.Günther Beck von Mannagetta und Lerchenau was the first to treat N. edwardsiana in synonymy with N. villosa when he published his monograph on the genus in 1895.

He suggested that N. villosa is a stunted form of N. edwardsiana from higher elevations, which flowers at a "juvenile stage of development".

[5] Whereas N. edwardsiana and N. villosa are restricted to the Kinabalu area, N. macrophylla is only found near the summit of Mount Trus Madi.

[5] Matthew Jebb and Martin Cheek suggest that N. villosa is related to N. mira, a species endemic to Palawan in the Philippines.

However, N. villosa plants from Mount Tambuyukon are easier to confuse with this hybrid, as they produce pitchers that may be elongated slightly above the hip.

[5] Nepenthes × harryana is known from a ridge above the Upper Kolopis River and from two locations along the Kinabalu summit trail.

It was first collected near Kambarangoh on Mount Kinabalu by Lilian Gibbs in 1910 and later mentioned by John Muirhead Macfarlane as "Nepenthes sp."

[33] Although Macfarlane did not formally name the plant, he noted that "[a]ll available morphological details suggest that this is a hybrid between N. villosa and N.

The name was published in Nepenthes of Mount Kinabalu, but it is a nomen nudum, as it had an inadequate description and lacked information on the type specimen.

[5] More specifically, plants are known from a footpath near Paka Cave and several places along an unestablished route on a south-east ridge, which lies on the west side of the Upper Kolopis River.

[33] The only accessible location from which this hybrid is known is the Kinabalu summit trail, between Layang-Layang and the helipad, where it grows at about 2,900 m (9,500 ft) in a clearing dominated by Dacrydium gibbsiae and Leptospermum recurvum trees.

In general, pitchers are larger than those of N. villosa and the tendril joins the apex about 1–2 cm (0.4–0.8 in) below the leaf tip, a feature which is characteristic of N.

N. × kinabaluensis is an indumentum of villous hairs covering the pitchers and leaf margins, which is approximately intermediate between the parents.

However, it has been confused once before, when the hybrid was misidentified as both N. rajah and N. villosa[39] in Letts Guide to Carnivorous Plants of the World, published in 1992.

[14] —Ascidia magna turgida late pyriformia coriacea, 5" longa, 3½" lata, alis anticis mediocribus grosse dentatis, ore aperto annulo maximo!

lamellis annularibus distantibus disciformibus rigidis, 1" diam., cristatis posticis in spinas rigidas ½" longas, fundum ascidii spectantibus productis, collo elongato erecto, operculo orbiculato intus densissime glanduloso dorso basi longe cornuto.

Folia mediocria petiolata, lamina obovato-oblonga v. lanceolata, nervis longitudinalibus utrinque 2-3, vagina caulem fere totum amplectente; ascidia rosularum ignota; ascidia inferiora magna, breviter ovata, costis 2 ad os alatis fimbriatis; peristomio operculum versus in collum elongato 6-12 mm lato, costis altis 3-12 mm distantibus, dentibus 1-3 x longioribus quam latis; operculo rotundato-cordato v. paulum reniformi, facie inferiore plano; ascidia superiora magna, parte inferiore ventricosa os versus cylindrica, costis 2 prominentibus; peristomio operculum versus in collum elevato, 12-22 mm lato, costis altis 3-12 mm distantibus, dentibus 1-3 x longioribus quam latis; operculo rotundato-ovato v. paulum reniformi, facie inferiore plano; inflorescentia racemus pedicellis inferioribus 12 mm longis omnibus 1-floris; indumentum villosum.