[2] In his Carnivorous Plant Database, taxonomist Jan Schlauer treats N. leonardoi as a heterotypic synonym of N. deaniana.

[4] Nepenthes leonardoi was discovered on November 18, 2010, by Greg Bourke, Jehson Cervancia, Mark Jaunzems, and Stewart McPherson.

[5] Nepenthes leonardoi was formally described in the March 2011 issue of Carniflora Australis by McPherson, Bourke, Cervancia, Jaunzems, and Alastair Robinson.

[2] The specific epithet leonardoi honours Filipino botanist Leonardo Co, who was killed on the island of Leyte on November 15, 2010,[2] reportedly as a result of "crossfire between government security forces and an insurgent group".

[5] As explained in the species's describing paper:[2] The first four authors of this species discovered this plant on November 18th, and felt it fitting to name this plant, which is unique among Philippine Nepenthes in producing black pitchers, after Leonardo, in honour of his lifework and many accomplishments.The herbarium specimen S. McPherson SRM 5 is the designated holotype, and is deposited at the herbarium of Palawan State University (PPC), Puerto Princesa City.

[2] It was collected on November 20, 2010, near the summit of Schom-carp Peak at 1490 m.[2] In preparing the species description, the describing authors also examined herbarium material of a number of closely allied species, including N. attenboroughii (specimens A.Robinson AR001 and AR002), N. mantalingajanensis (G.C.G.Argent & E.M.Romero 92114), N. mira (G.C.G.Argent et al. 25438), and N. rajah (Low s.n.).

Plants found under the shade of dense vegetation typically have longer internodes compared to those growing in more open areas, although the latter on average bear larger pitchers and inflorescences.

This being the case, exceptional specimens (also found in exposed areas) may produce a rigid inflorescence up to 110 cm length, of which only the distal 15% bears flowers.

Inflorescences of both sexes have a basal diameter of approximately 1 cm and hold up to around 120 closely packed flowers, which are usually restricted to the distal quarter to half of its length.

Male flowers are fragrant; their scent has been described as "distinctive, musty, sweet" and is noticeable from a distance of up to 60 cm.

[2] A sparse indumentum of simple, reddish-brown hairs is present on certain vegetative parts, including the outside of the pitchers, the laminar margins, the lower surface of the midrib, and the tendrils (where they are somewhat more densely distributed).

The laminae and petioles are often green throughout when produced in shaded conditions and red to purple in plants exposed to direct sunlight.

Lower pitchers are most commonly orange to red on their outer surfaces, often flecked with slightly darker purple markings.

Beyond this common pigmentation, both lower and upper pitchers exhibit a continuum of colours across the species, from wholly yellowish-green at one extreme to entirely burgundy at the other.

The altitudinal distribution of N. leonardoi ranges from at least 1300 m above sea level to the summit of Schom-carp at 1490 m. The only known population numbers several thousand individuals.

Like its close relatives,[note a] N. leonardoi is apparently outcompeted by bamboo and is consequently largely or completely absent from the highest parts of the eastern ridge.

Although the habitat of N. leonardoi remains untouched by human activity, the describing authors cited mining operations to the south, on the Mount Victoria massif (to which N. attenboroughii is endemic), as a possible future threat if appropriate conservation measures are not taken.