''Nepenthes sibuyanensis'' is a tropical

pitcher plant Pitcher plants are several different carnivorous plants which have modified leaves known as pitfall traps—a prey-trapping mechanism featuring a deep cavity filled with digestive liquid. The traps of what are considered to be "true" pitcher p ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Sibuyan Island Sibuyan is a crescent-shaped island, the second largest in an archipelago comprising Romblon Province, Philippines. Located in the namesake Sibuyan Sea, it has an area of and has a total population of 62,815 as of 2020 census. The island has t ...

in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

, after which it is named.

Botanical history

''Nepenthes sibuyanensis'' was discovered during an expedition to the

beginning in September 1996. The team comprised Thomas Alt, Phill Mann, Trent Smith, and Alfred Öhm. The species was formally described by

Joachim Nerz Dr. Joachim Nerz (born 1964) is a German taxonomist and botanist specialising in the carnivorous plant genera ''Heliamphora'' and '' Nepenthes''. Nerz has described several new species, mostly with Andreas Wistuba. Publications * Schlauer, J. ...

in the March 1998 issue of the ''

Carnivorous Plant Newsletter The ''Carnivorous Plant Newsletter'' is the official publication of the International Carnivorous Plant Society (ICPS), the largest such organization in the world. It is headquartered in Walnut Creek, California. History and editorship The newsle ...

''.

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

of ''N. sibuyanensis'', sheet 051001, was collected on October 5, 1996, by Phill Mann and Trent Smith on

Mount Guiting-Guiting Mount Guiting-Guiting or G2 is the highest mountain in the province of Romblon, located in Sibuyan Island, in the Philippines, with an elevation of above sea level. Its steep slopes and jagged peak, have earned it the reputation, as one of the mo ...

at an elevation of 1300 m above sea level. The plant was growing on an open slope amongst high grasses and

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except t ...

s of the genus ''

Dipteris ''Dipteris'' is a genus of about seven species of ferns, native to tropical regions across the world, particularly Asia, with a species in northeastern Queensland in Australia. It is one of two genera in the family Dipteridaceae. Description Sp ...

''. 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 National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, ce ...

Leiden Leiden (; in English and archaic Dutch also Leyden) is a city and municipality in the province of South Holland, Netherlands. The municipality of Leiden has a population of 119,713, but the city forms one densely connected agglomeration wit ...

. It was initially suggested, based on early field observations, that ''N. sibuyanensis'' did not produce true upper pitchers and that lower pitchers were almost exclusively produced under

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

coverMansell, G. N.d
''Nepenthes sibuyanensis'' in cultivation
. Exotica Plants. (the authors of the describing paper mention finding only a single pitcher growing in sunlight). Cultivated plants and subsequent field studies disproved both of these hypotheses. The first use of the name ''N. sibuyanensis'' greatly predates the formal description of this species. A certain "''Nepenthes sibuyanensis Elm.''" appears in the December 29, 1911 issue of ''

Leaflets of Philippine Botany Leaflet may refer to: * Leaflet (botany), part of a compound leaf * Leaflet (software), a JavaScript library for interactive maps * Pamphlet, a type of publication ** Folded leaflet ** Flyer (pamphlet) ** Airborne leaflet propaganda * Cusps of he ...

'', in an article by

Adolph Daniel Edward Elmer Adolph Daniel Edward Elmer (June 14, 1870 – 1942) was an American botanist and plant collector.. He was mostly active in the Philippines, his collections being described as new species by both himself and other botanists. The Japanese sent him ...

on the

figs The fig is the edible fruit of ''Ficus carica'', a species of small tree in the flowering plant family Moraceae. Native to the Mediterranean and western Asia, it has been cultivated since ancient times and is now widely grown throughout the world ...

of Sibuyan. Elmer wrote that this ''Nepenthes'' formed part of the summit vegetation of

, which was "washed down and disseminated as botanical floats" along the Pauala River, where he observed it.

Description

''Nepenthes sibuyanensis'' is a weak climber. The stem can attain a length of 1.5 mMann, P. 1998
A trip to the Philippines
''

'' 27(1): 6–11. and is up to 8 mm in diameter. Internodes are up to 1.5 cm long and cylindrical in cross section. Leaves are thin-

coriaceous This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

and

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

. The

lamina Lamina may refer to: Science and technology * Planar lamina, a two-dimensional planar closed surface with mass and density, in mathematics * Laminar flow, (or streamline flow) occurs when a fluid flows in parallel layers, with no disruption betwee ...

is linear-

lanceolate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

to slightly

spathulate This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

in shape. It may be up to 18 cm long and 5 cm wide. The lamina has an acute apex and is gradually

attenuate In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable a ...

towards the base. It is

decurrent ''Decurrent'' (sometimes decurring) is a term used in botany and mycology to describe plant or fungal parts that extend downward. In botany, the term is most often applied to leaf blades that partly wrap or have wings around the stem or petio ...

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 This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

Tendril In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape used by climbing plants for support and attachment, as well as cellular invasion by parasitic plants such as ''Cuscuta''. There are many plants that have tendr ...

s are usually one to two times as long as the pitchers and up to 9 mm wide near the pitcher. 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. 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 Peristome (from the Greek ''peri'', meaning 'around' or 'about', and ''stoma'', 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes. In mosses In mosses, ...

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 inner portion of the peristome accounts for around 54% of its total cross-sectional surface length.Bauer, U., C.J. Clemente, T. Renner & W. Federle 2012. Form follows function: morphological diversification and alternative trapping strategies in carnivorous ''Nepenthes'' pitcher plants. ''Journal of Evolutionary Biology'' 25(1): 90–102. The

gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

ular region covers the entire inner surface of the pitchers; there is no waxy zone. 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 Cordate is an adjective meaning 'heart-shaped' and is most typically used for: * Cordate (leaf shape), in plants * Cordate axe, a prehistoric stone tool See also * Chordate A chordate () is an animal of the phylum Chordata (). All chordat ...

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 Filiform, thread or filament like, can refer to: *Filiform, a common term used in botany to describe a thread-like shape *Filiform, or filiform catheter, a medical device whose component parts or segments are all cylindrical and more or less uni ...

spur A spur is a metal tool designed to be worn in pairs on the heels of riding boots for the purpose of directing a horse or other animal to move forward or laterally while riding. It is usually used to refine the riding aids (commands) and to back ...

(≤3 mm long) is inserted near the base of the lid. Upper pitchers are very rarely produced. They are generally smaller and lighter-coloured than their terrestrial counterparts. ''Nepenthes sibuyanensis'' has a

racemose A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

. In male inflorescences, the peduncle reaches a length of at least 18 cm, whereas the

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

is up to 15 cm long.

Pedicels In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...

are one-flowered, up to 14 mm long, and usually lack

bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

Tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...

s are oblong, obtuse, and approximately 3 mm long.

Stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

s are around 5 mm long including the uniseriate

anther The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

Fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

s are up to 22 mm long and bear lanceolate valves (≤4 mm wide).

Seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s are up to 8 mm long and

, although they lack the papery ends typical of most ''Nepenthes'' species.Rybka, V., R. Rybková & R. Cantley 2005
''Nepenthes argentii'' on Sibuyan Island.
''

'' 34(2): 47–50. The inflorescence bears a very dense

indumentum In biology, an indumentum (Latin, literally: "garment") is a covering of trichomes (fine "hairs") on a plant Davis, Peter Hadland and Heywood, Vernon Hilton (1963) ''Principles of angiosperm taxonomy'' Van Nostrandpage, Princeton, New Jersey, pa ...

of adpressed, stellate hairs. The staminal column is covered in short hairs. Vegetative parts of the plant are virtually

glabrous Glabrousness (from the Latin ''glaber'' meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of ...

. 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.

Ecology

''Nepenthes sibuyanensis'' is

in the

, where it grows on

, neighbouring Mount Mayo, as well as the ridge that connects these two mountains. The altitudinal distribution given for this species varies considerably between sources: Vlastik Rybka, Romana Rybková and Rob Cantley give a range of 1200–1800 m above sea level, while the authors of the describing paper and Stewart McPherson give narrower ranges of 1500–1800 m and 1250–1500 m, respectively. According to Rybka, Rybková and Cantley, the species is sympatric with the tiny '' N. argentii'' at around 1600–1770 m.Jebb, M.H.P. & M.R. Cheek 1997. A skeletal revision of ''Nepenthes'' (Nepenthaceae). ''Blumea'' 42(1): 1–106. A species resembling '' N. alata'' grows on Mount Guiting-Guiting at lower elevations of 800–1000 m; it was described as '' N. graciliflora'' by

. 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 ''Lobelia'' () is a genus of flowering plants comprising 415 species, with a cosmopolitan distribution, subcosmopolitan distribution primarily in tropical to warm temperate regions of the world, a few species extending into cooler temperate reg ...

'' and ''

Rhododendron rousei ''Rhododendron rousei'' is a species of ''Rhododendron'' native to the Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Fil ...

''. ''Nepenthes sibuyanensis'' has no known

natural hybrid In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in ...

s, although it may hybridise with ''N. argentii''.McPherson, S.R. 2009. ''

Pitcher Plants of the Old World ''Pitcher Plants of the Old World'' is a two-volume monograph by Stewart McPherson on the pitcher plants of the genera ''Nepenthes'' and ''Cephalotus''. It was published in May 2009 by Redfern Natural History Productions and covers all species kno ...

''. 2 volumes. Redfern Natural History Productions, Poole. ''Nepenthes sibuyanensis'' occurs relatively sparsely on open slopes dominated by high grasses, small shrubs, and the fern ''

Dipteris conjugata ''Dipteris conjugata'' is a species of fern. It has a rhizome, and 2-3 tall stems with mid green or dark green fronds, which have several divisions to toothed lobes. It is grows in clearings, mountain ridges and in forest margins, from tropical a ...

''. Pitchers usually develop embedded in the substrate and are rarely exposed to direct sunlight. ''Nepenthes sibuyanensis'' exhibits modified seed morphology owing to its exposed, isolated habitat. The absence of seed wings in this species prevents strong winds carrying them away from suitable habitats and allows for dispersion by water (particularly rainfall and small streams). Due to its localised distribution, the

conservation status The conservation status of a group of organisms (for instance, a species) indicates whether the group still exists and how likely the group is to become extinct in the near future. Many factors are taken into account when assessing conservation ...

of ''N. sibuyanensis'' is listed as Vulnerable on the 2006 IUCN Red List of Threatened Species.

Logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. Logging is the beginning of a supply chain ...

and

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...

operations are increasingly threatening Mount Guiting-Guiting and its national park.

Related species

''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 New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

.Danser, B.H. 1928.

The Nepenthaceae of the Netherlands Indies "The Nepenthaceae of the Netherlands Indies" is a seminal monograph by B. H. Danser on the tropical pitcher plants of the Dutch East Indies and surrounding regions. It was originally published in the ''Bulletin du Jardin Botanique de Buitenzorg'' ...

. ''Bulletin du Jardin Botanique de Buitenzorg'', Série III, 9(3–4): 249–438. It appears to be intermediate between ''N. merrilliana'' and ''N. ventricosa'' in terms of both morphology and geographical distribution. In addition, the newly described ''

Nepenthes barcelonae ''Nepenthes barcelonae'' is a tropical pitcher plant native to the Philippine island of Luzon. It is known from a single mountain in the Sierra Madre range of Aurora Province, where it grows in stunted submontane forest. The specific epithet '' ...

'' from

Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...

has been classified by the authors as a member of this group. 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 Ventricose is an adjective describing the condition of a mushroom, gastropod or plant that it is "swollen, distended, or inflated especially on one side". Mycology In mycology, ventricose is a condition in which the cystidia, lamella or stipe of a ...

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 In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...

. 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.

Notes

:a.The original

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

description of ''N. sibuyanensis'' reads:

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.

References

External links

* {{Taxonbar, from=Q2239312 Carnivorous plants of Asia sibuyanensis Endemic flora of the Philippines Flora of Luzon Vulnerable flora of Asia Plants described in 1998