once by Jacob Gijsbert Boerlage in 1900 as N. eustachia. Description Nepenthes eustachya is a climbing plant. The stem attains a length of up to 5 m and a diameter of 0.8 cm. Internodes are cylindrical in cross section and up to 12 cm long. Leaves are coriaceous and petiolate. The lamina is oblong-lanceolate in shape and can be up to 20 cm long and 5 cm wide. It has a rounded to emarginate apex, which may be sub-peltate. The petiole is canaliculate, not decurrent, and generally lacks wings. It clasps the stem for around half of its circumference. Two to four longitudinal veins are present on either side of the midrib. Pinnate veins arise obliquely from the midrib. Tendrils reach 15 cm in length. Rosette and lower pitchers are ovoid in the lowermost quarter and cylindrical above, frequently widening just below the peristome. They are up to 20 cm high and 4 cm wide. On the inner surface, the glandular region covers the ovoid portion of the pitcher cup. The pitchers lack wings, bearing a pair of ribs instead. The pitcher mouth is round and has an oblique insertion. The flattened peristome may be up to 5 mm wide. Its inner margin is lined with indistinct teeth. The inner portion of the peristome accounts for around 29% of its total cross-sectional surface length. The lid is sub-orbicular and lacks appendages. The spur is up to 4 mm long and generally bifid. Upper pitchers resemble their lower counterparts in most regards. They usually attain a slightly greater size and are infundibular in the uppermost quarter. Nepenthes eustachya has a racemose inflorescence. The peduncle is up to 40 cm long, whereas the rachis reaches 30 cm in length. Partial peduncles are one- or two-flowered and lack bracteoles. Sepals are lanceolate in form and up to 4 mm long. Immature parts of the plant may bear a sparse indumentum of white, mostly caducous hairs. Mature parts are glabrous throughout. The stem and lamina are green. Pitchers are white to light pink with many red speckles. The underside of the lid is often darker than the rest of the pitcher. The peristome is usually yellowish and may bear red stripes. Ecology Nepenthes eustachya is endemic to the Indonesian provinces of North Sumatra and West Sumatra; its natural range stretches from Sibolga to the Padang Highlands. It has an altitudinal distribution of 0–1600 m