Сибуян аралдық қапшық гүлі (Sibuyan araldyq qapshyq gúli)

Species of pitcher plant from the Philippines

Nepenthes sibuyanensis /n//ᵻ/'/p//ɛ//n//θ//iː//z// //s//ɪ/,/b//ʊ//j//ə/'/n//ɛ//n//s//ɪ//s/ is a tropical pitcher plant endemic to Sibuyan Island in the Philippines, after which it is named.

Nepenthes sibuyanensis was discovered during an expedition to the Philippines beginning in September 1996. The team comprised Thomas Alt, Phill Mann, Trent Smith, and Alfred Öhm. The species was formally described by Joachim Nerz in the March 1998 issue of the Carnivorous Plant Newsletter. The holotype of N. sibuyanensis, sheet 051001, was collected on October 5, 1996, by Phill Mann and Trent Smith on Mount Guiting Guiting at an elevation of 1300 m above sea level. The plant was growing on an open slope amongst high grasses and ferns of the genus Dipteris. The specimen includes a typical pitcher and was chosen as the holotype because the pitchers of this species are its most characteristic feature. Mann and Smith made three further collections of N. sibuyanensis on the same day and at the same altitude. These were sheet 051002, which includes vegetative parts without pitchers, sheet 051003, which consists of fruits, and sheet 051004, which includes male flowers. All four specimens are deposited at the National Herbarium of the Netherlands in Leiden. (the authors of the describing paper mention finding only a single pitcher growing in sunlight). and is up to 8 mm in diameter. Internodes are up to 1.5 cm long and cylindrical in cross section. The glandular region covers the entire inner surface of the pitchers;

The inflorescence bears a very dense indumentum of adpressed, stellate hairs. The staminal column is covered in short hairs. Vegetative parts of the plant are virtually glabrous. A species resembling N. alata grows on Mount Guiting Guiting at lower elevations of 800–1000 m; Nepenthes armin also occurs on Mt. Guiting Guiting and on a ridge leading to Mt. Mayo, however it is found at lower elevations and within a more restricted area (750 m). Other plant species endemic to the mountain include Lobelia proctorii and Rhododendron rousei. Nepenthes sibuyanensis has no known natural hybrids, although it may hybridise with N. argentii. Nepenthes sibuyanensis occurs relatively sparsely on open slopes dominated by high grasses, small shrubs, and the fern Dipteris conjugata. Pitchers usually develop embedded in the substrate and are rarely exposed to direct sunlight.

Nepenthes sibuyanensis belongs to B. H. Danser's Insignes group, which also includes the closely related Philippine species N. burkei, N. merrilliana, and N. ventricosa, as well as N. insignis from New Guinea. It appears to be intermediate between N. merrilliana and N. ventricosa in terms of both morphology and geographical distribution. The species can be distinguished from both N. burkei and N. ventricosa on the basis of its pitcher shape; the traps of N. sibuyanensis are ovate to slightly infundibulate, whereas those of the latter species are ventricose in the lower part and constricted in the middle. In addition, the pitchers of N. burkei and N. ventricosa are smaller, rarely exceeding 20 cm in height. Nepenthes merrilliana produces the largest pitchers in the Insignes group and, unlike N. sibuyanensis, has two flowered pedicels. Furthermore, its pitchers bear a pair of well developed fringed wings. Nepenthes sibuyanensis has also been compared to N. insignis. The former produces one flowered pedicels, whereas those of N. insignis are two flowered. The pitcher mouth of N. sibuyanensis is almost horizontal, compared to oblique in the latter. In addition, the peristome of N. sibuyanensis forms a short neck, while N. insignis lacks a neck completely. Furthermore, N. insignis has shorter peristome teeth than N. sibuyanensis (1 mm versus 5 mm). The pitchers of N. sibuyanensis also differ in shape, being ovate or slightly infundibulate.