Nepenthes saranganiensis — 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

The leaves are linear to spathulate, to 30 cm long and 7 cm wide, passing into a winged petiole up to three centimetres wide. The leaf base runs down the stem like a ribbon, up to one and a half centimetres wide at the leaf axils, and gives the stem four conspicuous wings. Lower pitchers are to 18 cm tall, ovate below and cylindrical or funnel-shaped above, with two wings up to 12 mm wide and fringes up to a centimetre long. Upper pitchers are larger, to 32 cm, with strongly reduced or inconspicuous wings. The peristome is up to 11 mm wide, loosely cylindrical or slightly flattened; the lid up to 5 cm long. Colours vary widely: yellow, green, orange, red and purple, often striped or speckled. According to Cheek and Jebb, lower and upper pitchers are sometimes very alike.

Similar species

The most similar species is Nepenthes tboli, from the same part of Mindanao; it has, however, terete stems without wings, hairy leaf margins and midribs, and a narrow peristome of less than three millimetres. In the identification key of Cheek and Jebb (2013), Nepenthes saranganiensis is the only species of the alata group whose internodes are winged by the decurrent petiole bases; in practice that one character suffices. Other Mindanao species of the group, such as Nepenthes mindanaoensis and Nepenthes ramos, have round stems.

The trap and how it works

A pitfall trap with two pitcher forms that differ less than usual in this species. Lower pitchers carry broad fringed wings that guide crawling animals to the mouth; upper pitchers hang from the tendrils and catch mainly flying insects. The peristome bears ribs up to half a millimetre high and half a millimetre apart, which turn slippery when wet. The lid stands about 45 degrees above horizontal and carries a dense band of large nectar glands along the midline, with a convex appendage at its base. No targeted studies of prey or digestive fluid have been published.

Habitat and ecology

Here the sources contradict each other. Cheek and Jebb (2013) describe the species as a terrestrial shrub in open, shrubby terrain at 700 to 800 m (B5). Another description, taken over in the Nepenthaceae treatment of the Caryophyllales Network, calls it a strict epiphyte on mossy branches of tall trees in lower montane forest at 1800 to 2100 m (B1). Both pictures may be right if the species has a broad ecological range, but it may also be that different plants have been described under one name. For that reason the elevation field is left empty.

Distribution and elevation

Endemic to the Philippines, in southern Mindanao. The name refers to Sarangani Province; Cheek and Jebb place the species in southern South Cotabato, which borders Sarangani. This guide gives no more precise sites. Southern Mindanao is under-explored botanically, and the species' distribution within the region is poorly known.

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 formally described, but pitcher colour varies strongly, from yellow and green to orange, red and purple, with stripes and speckles to varying degrees. No natural hybrids are known. The uncertainty about habitat and altitude makes renewed fieldwork desirable, with herbarium material from both kinds of site.

Where and when to see it

Anyone meeting pitcher plants in southern Mindanao can decide with one look at the stem: four ribbon-like wings along the stem almost certainly mean this species. Look both in open scrub at middle elevations and, with binoculars, in the mossy crowns of montane forest higher up. Dated photographs with altitude and habitat could help resolve the contradiction in the literature. Check the security situation in the area beforehand.

Conservation status

The species has not (yet) been assessed for the Red List. Little is known about the size of its populations. Southern Mindanao suffers heavily from forest clearance for agriculture, and open, shrubby ground at middle elevations is often converted to fields or plantations. As a member of Nepenthes it is listed in CITES Appendix II, so international trade in wild plants requires a permit.

Scientific name

Nepenthes saranganiensis | Kurata, 2003

Nepenthes saranganiensis was described in April 2003 by Shigeo Kurata, in "A new Philippine pitcher plant, the third species having a saddle-shaped stem" (Journal of Insectivorous Plant Society 54(2): 41-44). The precise type locality could not be established with certainty; the species is native to the Sarangani area of Mindanao, Philippines. The specific epithet derives from Sarangani, a location on Mindanao where the plant is native.

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