Nepenthes klossii belongs to the loosely defined "N. maxima complex", which also includes, among other species, N. boschiana, N. chaniana, N. epiphytica, N. eymae, N. faizaliana, N. fusca, N. maxima, N. platychila, N. stenophylla, and N. vogelii.

In terms of pitcher morphology, N. klossii resembles N. aristolochioides in some respects, although the pitchers of the former are much larger.
However, the two species are geographically isolated from each other and are not thought to be closely related.
The unique adaptations of these taxa are thought to represent an example of convergent evolution, whereby two organisms that are not closely related independently acquire similar characteristics while evolving in separate, but comparable, ecosystems.
Nepenthes klossii can be distinguished from N. aristolochioides on the basis of its much larger, petiolate laminae.

Nepenthes eustachya from Sumatra exhibits considerable variability and occasionally produces hooded upper pitchers that superficially resemble those of N. klossii.
However, these species are otherwise easy to distinguish.
Nepenthes klossii belongs to the loosely defined "N. maxima complex", which also includes, among other species, N. boschiana, N. chaniana, N. epiphytica, N. eymae, N. faizaliana, N. fusca, N. maxima, N. platychila, N. stenophylla, and N. vogelii.
In terms of pitcher morphology, N. klossii resembles N. aristolochioides in some respects, although the pitchers of the former are much larger. However, the two species are geographically isolated from each other and are not thought to be closely related. The unique adaptations of these taxa are thought to represent an example of convergent evolution, whereby two organisms that are not closely related independently acquire similar characteristics while evolving in separate, but comparable, ecosystems. Nepenthes klossii can be distinguished from N. aristolochioides on the basis of its much larger, petiolate laminae.
Nepenthes eustachya from Sumatra exhibits considerable variability and occasionally produces hooded upper pitchers that superficially resemble those of N. klossii. However, these species are otherwise easy to distinguish.
Nepenthes klossii