Nepenthes sibuyanensis
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 A lower pitcher of N. sibuyanensis from Mount Guiting-Guiting
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| Nepenthes sibuyanensis Nerz (1998) |
Nepenthes sibuyanensis (pronounced /nəˈpɛnθiːz sɪˈbʊjɑːnˌensɪs/) is a tropical pitcher plant endemic to Sibuyan Island in the Philippines, after which it is named.
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[edit] Botanical history
N. sibuyanensis was discovered during an expedition to the Philippines beginning in September 1996 that focused on Nepenthes. The team comprised Thomas Alt, Phill Mann, Trend Smith, and Alfred Öhm. The species was formally described[I] by Joachim Nerz in a 1998 issue of the Carnivorous Plant Newsletter.[1][2]
The holotype of N. sibuyanensis, sheet 051001, was collected on October 5, 1996, by Phill Mann and Trend 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.[1]
[edit] Description
N. sibuyanensis is a weak climber. The stem can attain a length of 1.5 m[3] and is up to 8 mm in diameter. Internodes are up to 1.5 cm long and cylindrical in cross section.[1]
Leaves are thin-coriaceous and sessile. The lamina is linear-lanceolate to slightly spathulate in shape. It may be up to 18 cm long and 5 cm wide.[3] The lamina has an acute apex and is gradually attenuate towards the base. It is decurrent into a pair of margins that extend for over two-thirds of the internode. Five to six longitudinal veins are present on either side of the midrib. Tendrils are usually one to two times as long as the pitchers and up to 9 mm wide near the pitcher.[1]
Pitchers arise from the end of the tendril, forming a tightly appressed curve. Lower pitchers are ovate to infundibuliform in shape and may be up to 26 cm high and 15 cm wide.[3] Upper pitchers are very rarely produced. They are smaller and lighter-coloured than their terrestrial counterparts. A pair of ribs runs down the front of the pitcher, sometimes bearing fringe elements (≤3 mm wide) near the peristome. The pitcher mouth is oval and has an almost horizontal to slightly oblique insertion. The peristome is cylindrical, usually elongated into a short neck, and up to 20 mm wide. It bears a series of ribs (≤1 mm high) spaced 2 mm apart. The teeth lining the inner margin of the peristome are up to 4 mm long. The glandular region covers the entire inner surface of the pitchers. The glands are up to 0.8 mm in diameter and occur at a density of 200 to 500 per square centimetre. The lid or operculum is broadly ovate-cordate and up to 8 cm long and 6.5 cm wide. It has a rounded apex and lacks appendages. A number of ovate glands (≤1 mm in diameter) are concentrated near the centre of the lid's lower surface. A filiform spur (≤3 mm long) is inserted near the base of the lid.[1]
N. sibuyanensis has a racemose inflorescence. In male inflorescences, the peduncle reaches a length of at least 18 cm, where as the rachis is up to 15 cm long. Pedicels are one-flowered, up to 14 mm long, and usually lack bracts. Tepals are oblong, obtuse, and approximately 3 mm long. Stamens are around 5 mm long including the uniseriate anthers. Fruits are up to 22 mm long and bear lanceolate valves (≤4 mm wide). Seeds are filiform and up to 8 mm long.[1]
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.[1]
Leaves are yellowish to dark green with a light green midrib. The stem and leaf margins may have reddish highlights. Lower pitchers are yellowish to red, often with scattered red blotches (≤10 mm in diameter) below the peristome. The peristome is usually darker than the rest of the pitcher, being dark red to almost black. The lid is yellowish to orange. Upper pitchers are lighter-coloured and usually whitish throughout. Herbarium specimens range in colour from light brown to red.[1]
[edit] Ecology
N. sibuyanensis is endemic to Mount Guiting-Guiting on Sibuyan Island in the Philippines. It has an altitudinal distribution of 1300 to 1800 m above sea level. It is sympatric with the tiny N. argentii at around 1800 m.[4][5] A species resembling N. alata grows on Mount Guiting-Guiting at lower elevations of 800 to 1000 m.[1] Other plant species endemic to the mountain include Lobelia proctorii[6] and Rhododendron rousei.[7]
N. 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.[1]
Due to its localised distribution, the conservation status of N. sibuyanensis is listed as Vulnerable on the 2006 IUCN Red List of Threatened Species.[8]
[edit] Related species
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A lower pitcher of N. burkei (left) and N. ventricosa (right)
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N. 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.[1][9] N. sibuyanensis appears to be intermediate between N. merrilliana and N. ventricosa in terms of both morphology and geographical distribution.[1]
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, where as 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.[1]
N. 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.[1]
N. 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.[1]
[edit] Notes
I. ^ The original Latin description of N. sibuyanensis reads:[1]
Folia mediocria sessilia, lamina lineari-lanceolata, nervis longitudinalibus utrinque 5-6, basi in alas 2 decurrente, vagina 0.; ascidia mediocria v. maiora, ovata v. infundibuliformia, costis 2 prominentibus, nonnunquam ad os rudimento alae ciliatae ornatis; peristomio operculum versus acuminato in collum breve elongato, applanato, 20 mm lato, costis 1.5 - 2 mm distantibus, dentibus 5 x longioribus quam latis. Operculo ovato-cordato, facie inferiore plano; inflorescentia racemus parvus pedicellis 8 mm longis, omnibus 1-floris; indumentum in partibus vegetativis subnullum, in inflorescentiis densum adpressum, e pilis simplicibus compositum.
[edit] References
- ^ a b c d e f g h i j k l m n o p Nerz, J., P. Mann, T. Alt & T. Smith 1998. Nepenthes sibuyanensis, a new Nepenthes from Sibuyan, a remote island of the Philippines. Carnivorous Plant Newsletter 27(1): 18–23.
- ^ Cheek, M.R. & M.H.P. Jebb 1998. Two New Philippine Nepenthes. Kew Bulletin 53(4): 966. doi:10.2307/4118886
- ^ a b c Mann, P. 1998. A trip to the Philippines. Carnivorous Plant Newsletter 27(1): 6–11.
- ^ Rybka, V., R. Rybkova & R. Cantley 2005. Nepenthes argentii on Sibuyan Island. Carnivorous Plant Newsletter 34(2): 47–50.
- ^ Jebb, M.H.P. & M.R. Cheek 1997. A Skeletal Revision of Nepenthes (Nepenthaceae). Blumea 42(1): 1–106.
- ^ Argent, G., P. Wilkie & D. Madulid 2007. Lobelia proctorii sp. nov. (Lobelioideae, Campanulaceae/Lobeliaceae) from the Philippines. Plant Ecology 192(2): 1385–0237. doi:10.1007/s11258-007-9306-9
- ^ Argent, G. & D. Madulid 1998. Rhododendron rousei (Ericaceae): a beautiful new species from the Philippines. New Plantsman 5(1): 25–31.
- ^ Clarke, C.M., R. Cantley, J. Nerz, H. Rischer & A. Witsuba 2000. Nepenthes sibuyanensis. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Listed as Vulnerable (VU D2 v2.3).
- ^ Danser, B.H. 1928. The Nepenthaceae of the Netherlands Indies. Bulletin de Jardin de Botanique, Buitenzorg, Série III, 9(3–4): 249–438.
[edit] External links
Miscellaneous: Nepenthes taxonomy • Nepenthes infauna
