Nepenthes harauensis — Vorstman's Guide to the Carnivorous Plants

No photograph of this species under a Creative Commons licence or in the public domain is in the guide yet.

Identification

A terrestrial climber to about 3 m, with cylindrical short shoots 0.8 to 1 cm thick and angular climbing stems half a centimetre thick with internodes of 4 to 7 cm. The leaves are thickly leathery and stalked; the petiole of 2 to 6 cm clasps three-quarters of the stem. The blade is elliptic-oblong, 9.5 to 16 cm long and 5 to 7 cm wide on short shoots, smaller on climbing stems. The tendrils are peltately attached, with two or three coils. Lower pitchers are ovoid in the lower half, constrict to a hip and become cylindrical above, with fringed wings and a peristome narrow at the front and widening to 1.4 cm at the back; the lid is cordate-orbicular, 4 to 5 cm. Upper pitchers are narrowly ovoid below and cylindrical above, widening slightly towards the mouth, with reduced wings.

Similar species

Its closest relatives are Nepenthes bongso and N. singalana, two highland species of West Sumatra. N. harauensis is distinguished by its strongly stalked leaves, found in no other Sumatran montane species, and by the peltate tendril attachment, which it shares only with N. bongso and N. rigidifolia. The pitchers become abruptly cylindrical or slightly widened in the upper half instead of ovoid; a rounded, thickened protrusion sits at the apex of the lid's underside; and the peristome lacks the inward expansion of its relatives. The describers considered a hybrid origin unlikely, since possible parent species are absent from Harau.

The trap and how it works

A pitfall of the ordinary kind, in two forms. Lower pitchers stand on or near the ground at the foot of the rock faces, are winged and catch mainly walking animals. Upper pitchers arise laterally from the tendril, are narrower and have a narrower peristome of a few millimetres, with three small lobes on each side. The lid carries a rounded, thickened protrusion at the apex of its underside; whether it acts as a nectar lure, as in related species, has not been studied. Nothing has been published on the prey of this species.

Habitat and ecology

Shaded rock faces in low, stunted forest on sandstone hills, at 1100 to 1400 m (B1). The plant grows on the ground at the foot of and on ledges along these faces, in a canyon landscape of sandstone outcrops. Other pitcher plants in the same setting include N. adnata, N. albomarginata and N. tenuis. The sandstone yields a poor, acid soil, and the shade and moist air in the canyons keep conditions cool and wet year round.

Distribution and elevation

Endemic to Sumatra, Indonesia, and known from a single area: Harau, in Lima Puluh Kota regency in the province of West Sumatra. At least six populations have been found there, all in protected forest. Altitude: 1100 to 1400 m. The area given in our species list (West Sumatra) agrees with the description and the world checklist.

Recorded (one-degree cells)

Distribution based solely on records at GBIF (Global Biodiversity Information Facility), not on TDWG regions — those are often far larger than the actual range. The light halo is the area around a record, the dark core the record itself. The darker square is the only one-degree cell — roughly a hundred and ten kilometres — in which the species has been recorded, from all GBIF records. This is coarser than for most species because hardly any record of this plant carries an accurate coordinate. It shows where the species has been seen, not where it occurs: an empty square means nothing.

Forms and variation

No varieties or forms have been described. Stem and midrib are pale green, sometimes purplish red; the leaves are light green above and paler below. Lower pitchers are reddish green with dark red blotches to wholly dark red; upper pitchers are narrower and lighter. No natural hybrids are mentioned; the describers do explicitly discuss whether the plant itself could be a hybrid, and reject it, because no combination of the species present in Harau could produce these characters.

Where and when to see it

Harau is a well-known scenic area of sheer sandstone walls, reached from Payakumbuh. The species does not grow along the tourist roads in the valley but higher in the hills, on shaded faces in stunted forest above 1100 m; look for it only with a local guide and with permission from the managers of the protected area. Watch for the stalked, thick leaves and the tendril arising below the leaf tip: they identify the plant even without pitchers. Take nothing; the populations are small.

Conservation status

The Red List data used by this guide hold no assessment for the species (Not Evaluated). The description reports at least six populations in the type area, with an estimated fewer than a hundred young plants. All known sites lie in protected forest, but the describers warn that illegal collecting could become a threat without timely management; newly described species are highly sought after by collectors. Like the whole genus, it is listed in CITES Appendix II.

Scientific name

Nepenthes harauensis | Hernawati, Satria & Lee, 2022

Nepenthes harauensis was described on 30 June 2022 by Hernawati, Rizki Satria and Ch'ien C. Lee, in Reinwardtia 21(1): 19-23. The Harau region (Harau Valley), West Sumatra, Indonesia — the only place where the species occurs, endemically. The specific epithet derives from the type locality — the Harau region of West Sumatra — following standard botanical convention for geographic epithets.

World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.