[1] The specific epithet robcantleyi honours Robert Cantley, who was involved in the plant's discovery, propagation, and introduction to cultivation.

[3][5] Nepenthes robcantleyi was discovered by Robert Cantley in January 1997, on a remote mountain on the island of Mindanao in the Philippines.

Cantley was exploring the site in search of N. truncata seeds for his recently established plant nursery, Borneo Exotics.

[1] Near the top of a small hill Cantley found a number of typical N. truncata plants as well as two mature individuals of a striking, previously unknown taxon.

Though bearing very dark pitchers with well-developed wings and a wide, flared peristome, the plants closely matched N. truncata in leaf morphology and were at the time assumed to represent a robust highland variant of this species.

The resulting plants closely matched the two individuals seen in the wild in both their morphology and dark pigmentation (though they exhibited some variation in peristome colour).

[7] Nepenthes robcantleyi, and particularly the 'Queen of Hearts' plant, has featured prominently in the company's Gold Medal-winning Chelsea Flower Show displays.

[1] The species is reported to be an easy grower and to do well in typical Nepenthes highland conditions, with warm days up to 25 °C, cool nights down to 12 °C, and high light levels.

[21][22][23] Nepenthes robcantleyi was formally described by Kew botanist Martin Cheek in the Nordic Journal of Botany.

[1] An independently paginated preprint of the type description was distributed on 2 December 2011, but the journal number in which it appeared was only issued on 6 January 2012 (though dated "2011").

Though this name has never been validly published (it is a nomen nudum)[25] and was therefore available for describing a new species, Cheek chose robcantleyi instead to avoid confusion between the two.

[1] The herbarium specimen Cheek 15877 is the designated holotype and is deposited at the Royal Botanic Gardens, Kew (K) in London, England.

[1] Wild plants resembling N. robcantleyi were found by Andy Smith and colleagues in 2011, but due to their epiphytic habit they could only be photographed at a distance.

[26][27] Smith managed to relocate the plants in 2013, and this time he was able to examine them more closely, showing that they were morphologically similar to N. robcantleyi and possibly conspecific with it.

The pitcher mouth is obcordate in shape and has a more-or-less oblique insertion, being horizontal at the front, rising slightly by 1 cm (rarely up to 3 cm) in the central portion, and rising abruptly at the rear to form a tall neck that curves forward, giving the mouth a concave appearance when viewed from the side.

It has a rounded apex and a base that is first shallowly and then abruptly cordate, with a sinus 2 cm wide and 5–8 mm deep.

The area of the lower lid surface outside the boss also bears glands, but these are much smaller (~0.05 mm in diameter) and sparsely distributed.

[1] The plants originally observed by Cantley grew at an altitude of around 1800 m above sea level in "submontane evergreen forest".

[7] In the type description Martin Cheek informally assessed the conservation status of N. robcantleyi as Critically Endangered based on the IUCN criteria, while noting that the species may already be extinct in the wild.

[1] On account of its vegetative and floral features—specifically the racemose inflorescence, pronounced petioles, flattened and expanded peristome, and basal and apical lid appendages—N.

Nepenthes robcantleyi retains fringed wings in its mature (largest) pitchers, while in N. truncata these are reduced to fringe-less ridges around 1 mm wide.

[1] In N. robcantleyi the shape of the pitcher lid ranges from broadly ovate to suborbicular, compared to oblong in N. veitchii.

[1] Given the small number of specimens originally observed by Cantley, there has been some speculation that N. robcantleyi may represent an F1 natural hybrid.

Nepenthes veitchii, a Borneo endemic, was discounted as a possible parent since N. robcantleyi shows no evidence of the conspicuous indumentum of that species, not even in a reduced state.

Moreover, N. robcantleyi exhibits a number of characters not seen in either N. truncata or N. veitchii, namely a basally domed lid, its associated concentration of nectar glands, and bracts on the partial peduncles.

Cheek speculated that N. robcantleyi might have evolved from a plant similar to N. veitchii that had spread to Mindanao by long-distance dispersal from Borneo and there acquired its present suite of characters.

The flower spike of N. robcantleyi is identical to N. truncata in nearly all respects, excluding the presence of floral bracts in the former and minor differences in measurement.

However, one of the original batch of 11 seed-grown plants (one of the four that were sent to Tony Paroubek in the US) produced pitchers roughly intermediate in appearance between those of N. robcantleyi and N. truncata.

[8][10] Since these species were sympatric at the site where the seeds were collected, it has been suggested that this cultivated specimen may have represented a natural cross between them.

This plant, which Paroubek called "clone C", was prone to producing deformed and slightly variegated leaves and eventually died.