The plants were growing on a ridge at approximately 1000 m above sea level, making N. tenuis an intermediate species.

[3] After several failed expeditions,[4] the species was finally rediscovered in the wild in late 2002 by a team comprising Andreas Wistuba, Joachim Nerz, Michael Schach, and others.

It has an acute apex and is gradually attenuate towards the base, clasping the stem for two-thirds of its width (without a sheath).

[3] In their 1997 monograph, Matthew Jebb and Martin Cheek reduced N. tenuis to a synonym of N. dubia "with some hesitation".

Material representing the natural hybrid N. inermis × N. talangensis (N. × pyriformis) was also identified by the authors as belonging to N.

[2] Nepenthes tenuis can be distinguished from N. jacquelineae by its linear-lanceolate leaf blade (as opposed to ovate-spathulate in the latter) and lack of large glands on the lower surface of the lid.

Finally, N. jacquelineae is far larger in stature compared with N. tenuis and its pitchers have a far more developed and broader peristome that is almost horizontal.

[2] In their description of the species, Nerz and Wistuba included a table of "characteristics which clearly distinguish Nepenthes tenuis from similar species":[3] Charles Clarke writes that "the obvious similarities between N. tenuis, N. talangensis and N. jacquelineae are suggestive of recent adaptive radiation, and add further weight to the argument that the non-volcanic mountains of Bukit Barisan are the primary source of morphological diversity in Sumatran Nepenthes".

[2] In 2001, Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia using 70 morphological characteristics of each taxon.

[9][10] Nepenthes tenuis is endemic to a region of the Tjampo river east of Taram in West Sumatra.

The lower parts of the stem may also be covered under a layer of moss, making the plants difficult to find in the wild.

In its natural habitat, the species is sympatric with N. adnata and grows in close proximity to N. albomarginata, N. ampullaria, N. eustachya, N. gracilis, N. longifolia, and N. reinwardtiana.

[1] The habitat of this species may be threatened in the near future by fires deliberately started to clear forest for agricultural purposes.

Folia mediocria sessilia lamina lanceolata, nervis longitudinalibus utrinque 3, basi attenuata 2/3 caulis amplectente.