Nepenthes tenuis Nerz & Wistuba

Nepenthes tenuis (/nɪˈpɛnθiːz ˈtɛnjuɪs/; from Latin tenuis 'thin, fine, slender') is a tropical pitcher plant endemic to the Indonesian island of Sumatra. The species was first collected in 1957, from a remote mountain in the western part of the island. It remained undescribed until 1994, and was only rediscovered in the wild in 2002. Prior to this, N. tenuis was known solely from a single photograph and dried herbarium specimen.

Discovery and naming

Nepenthes tenuis was first collected by Willem Meijer on August 24, 1957.^{[note a]} It was discovered near Taram, West Sumatra, in a sandstone region of the river Tjampo. The plants were growing on a ridge at approximately 1000 m above sea level, making N. tenuis an intermediate species. The habitat was described as "light sub-montane forest".^[2]

Nepenthes tenuis was formally described^{[note b]} as a species in 1994 by Joachim Nerz and Andreas Wistuba, based on a single specimen deposited by Meijer at the Leiden herbarium^{[note c]} and a black and white photograph from 1957 showing the freshly collected plant.^[3] After several failed expeditions,^[4] the species was finally rediscovered in the wild in late 2002 by a team comprising Andreas Wistuba, Joachim Nerz, Michael Schach, and others.^[5][6][7]

Description

Nepenthes tenuis is a climbing plant. The stem is slender (2–3 mm thick) and angular to rhomboid in cross section. Internodes are 5-6.5 cm long.^[3]

Leaves are sessile and coriaceous. The lamina is lanceolate in morphology, 5–6 cm long, and 1-1.5 cm wide. It has an acute apex and is gradually attenuate towards the base, clasping the stem for two-thirds of its width (without a sheath). The lamina has indistinct nervation. Three or so longitudinal veins are present on either side of the midrib, originating from the basal third of the midrib and running parallel to it in the outer half of the lamina. Pinnate veins are oblique and irregularly reticulate, although they are not easily distinguishable. Tendrils are approximately 1.5 times as long as the lamina, growing to 12 cm in length^[2] and 0.5–1 mm in thickness. The tendrils may or may not curl around surrounding objects for support.^[3]

Nepenthes tenuis is one of the smallest-pitchered species in the genus, possibly only second to N. argentii. Upper pitchers gradually arise from the ends of the tendrils, forming a 10 mm wide curve. They are widely infundibuliform (funnel-shaped) throughout and contracted below the mouth. These aerial pitchers are usually 2.5-4.5 cm high and 1.5-2.5 cm wide. Both lower and upper pitchers lack wings or fringe elements. Instead, they bear two prominent ribs running down the front, 3–5 mm apart. The glandular region covers the entire inner surface of the pitchers.^[2] The glands are small and occur at a density of 600-800 per square centimetre. The pitcher mouth is ovate and almost horizontal. The flattened peristome may be up to 6 mm wide, bearing ribs spaced ¹/₈ mm apart. The lid is narrow-elliptic, lacks appendages, and possesses two prominent veins, one on each side of the midrib. It is usually 1.5-2.5 cm long and 0.5-0.8 cm wide. Glands are evenly distributed on the underside of the lid. An unbranched, 1 mm long spur is inserted close to the base of the lid.^[3]

Most parts of the plant are glabrous, although some may be covered with a sparse indumentum of simple hairs. Herbarium specimens are dark brown in colour. On living plants, the pitchers are yellow-green and often have varying amounts of red-brown blotches. The peristome may be yellow to dark brown.^[3]

Taxonomy

In their 1997 monograph, Matthew Jebb and Martin Cheek reduced N. tenuis to a synonym of N. dubia "with some hesitation". Material representing the natural hybrid N. inermis × N. talangensis (N. × pyriformis) was also identified by the authors as belonging to N. dubia.^[8] However, this interpretation is not followed by Charles Clarke, who does not consider the three taxa to be conspecific.^[2]

Nepenthes dubia and N. tenuis can be distinguished with relative ease. Most obviously, the pitchers of N. tenuis have shorter, broader lids that are never reflexed beyond 180°, unlike those of N. dubia, which are always reflexed beyond 180°. The pitchers of N. tenuis are also differently coloured, often having red flecks on the outside, in contrast to those of N. dubia, which are usually a solid yellow or orange colour. The peristome of N. tenuis is also less tightly cylindrical than that of N. dubia.^[2]

Nepenthes tenuis can be distinguished from N. jacquelineae by its linear-lanceolate leaf blade (as opposed to ovate-spathulate in the latter) and lack of large glands on the lower surface of the lid. The lid of N. jacquelineae also differs by being noticeably contracted towards the base. Finally, N. jacquelineae is far larger in stature compared with N. tenuis and its pitchers have a far more developed and broader peristome that is almost horizontal.^[2]

In their description of the species, Nerz and Wistuba included a table of "characteristics which clearly distinguish Nepenthes tenuis from similar species":^[3]

Charles Clarke writes that "the obvious similarities between N. tenuis, N. talangensis and N. jacquelineae are suggestive of recent adaptive radiation, and add further weight to the argument that the non-volcanic mountains of Bukit Barisan are the primary source of morphological diversity in Sumatran Nepenthes".^[2]

In 2001, Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia using 70 morphological characteristics of each taxon. The following is part of the resultant cladogram, showing "Clade 1", which has 51% bootstrap support. Its most strongly supported subclade is the sister pair of N. inermis and N. dubia, having 95% support.^[2]

51%

N. aristolochioides

N. tenuis

95%

N. dubia

N. inermis

Natural habitat and distribution

Nepenthes tenuis grows in mossy forest and light sub-montane forest at the tops of sandstone ridges. The only known population occurs at an elevation of 1000–1200 m above sea level.^[9][10] Nepenthes tenuis is endemic to a region of the Tjampo river east of Taram in West Sumatra. Most ridges in this area have an elevation of just below 1000 m, although several exceed this height.^[11]

Terrestrial pitchers of N. tenuis often develop partially embedded in moss. The lower parts of the stem may also be covered under a layer of moss, making the plants difficult to find in the wild.

In its natural habitat, the species is sympatric with N. adnata and grows in close proximity to N. albomarginata, N. ampullaria, N. eustachya, N. gracilis, N. longifolia, and N. reinwardtiana. Despite this, no natural hybrids involving N. tenuis have been recorded.^[2][9]

Nepenthes tenuis is listed as Endangered on the 2014 IUCN Red List of Threatened Species.^[1] The habitat of this species may be threatened in the near future by fires deliberately started to clear forest for agricultural purposes.^[2]

Notes

References

• Bonhomme, V., H. Pelloux-Prayer, E. Jousselin, Y. Forterre, J.-J. Labat & L. Gaume 2011. Slippery or sticky? Functional diversity in the trapping strategy of Nepenthes carnivorous plants. New Phytologist 191(2): 545–554. doi:10.1111/j.1469-8137.2011.03696.x
• Hernawati & P. Akhriadi 2006. A Field Guide to the Nepenthes of Sumatra. PILI-NGO Movement, Bogor.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Nepenthes_tenuis&oldid=1118574571"

Nepenthes tenuis Nerz & Wistuba, 1994 è una pianta carnivora della famiglia Nepenthaceae^[2], endemica di Sumatra, dove cresce a 1000–1200 m.

Conservazione

La Lista rossa IUCN classifica Nepenthes tenuis come specie in pericolo.^[1]

Note

Bibliografia

• Clarke, C.M. 2001. Nepenthes of Sumatra and Peninsular Malaysia. Natural History Publications (Borneo), Kota Kinabalu.
• Nerz, J. & A. Wistuba 1994. Five new taxa of Nepenthes (Nepenthaceae) from North and West Sumatra. Carnivorous Plant Newsletter 23(4): 101–114.

Nepenthes tenuis is een vleesetende bekerplant uit de familie Nepenthaceae die endemisch is op Sumatra. De eerste specimina werden in 1957 verzameld. In 1994 werd de soort beschreven door Joachim Nerz en Andreas Wistuba, op basis van een foto en enkele gedroogde herbariumspecimina. De plant werd pas in 2002 herontdekt in West-Sumatra.

Beschrijving

Nepenthes tenuis is een klimplant met een stengel van twee tot drie millimeter in doorsnede. Hieraan dankt de plant de soortaanduiding tenuis, Latijn voor 'dun' of 'slank'. De internodiën zijn 5 tot 6,5 centimeter lang. De bladeren zijn 5 tot 6 centimeter lang en 1 tot 1,5 centimeter breed. De ranken die de bladeren met de vangbekers verbinden zijn tot twaalf centimeter lang.

Nepenthes tenuis behoort tot de Nepenthes-soorten met de kleinste vangbekers. Mogelijk zijn alleen de vangbekers van N. argentii kleiner. De trechtervormige bovenbekers zijn 2,5 tot 4,5 centimeter hoog en 1,5 tot 2,5 centimeter breed. De onderbekers ontwikkelen zich meestal verzonken in het mos en zijn hier moeilijk te onderscheiden. Zowel de bovenbekers als de onderbekers hebben geen vleugels aan de voorzijde, maar twee opvallende verticale ribbels die drie tot vijf millimeter uit elkaar staan. Het afgeplatte peristoom (bekerrand) is tot 6 millimeter breed en is bedekt met ribbels die tot in de beker lopen. Het operculum is ellipsvormig en is 1,5 tot 2,5 centimeter lang en 0,5 tot 0,8 centimeter breed.

De binnenzijde is geheel bedekt met zeer kleine klieren voor de verteringsenzymen. Deze hebben een dichtheid van 600 tot 800 per vierkante centimeter. Ze produceren een zeer dikke, slijmerige bekervloeistof. De vloeistof bedekt de binnenzijde van de beker met een dunne laag slijm en vangt als een vliegenstrip insecten die boven het vloeistofoppervlak vliegen.^[2]

Verspreiding

Nepenthes tenuis is endemisch in het stroomgebied van de rivier de Tjampo in West-Sumatra. Hier groeit de plant in nevelwouden en submontane bossen. De enige bekende populatie groeit op 1000 tot 1200 meter boven zeeniveau. In dit gebied is de soort sympatrisch met N. adnata. In de nabijheid groeien ook N. albomarginata, N. ampullaria, N. eustachya, N. gracilis, N. longifolia en N. reinwardtiana. Desondanks zij er geen natuurlijke hybriden van Nepenthes tenuis bekend

Bronnen, noten en/of referenties

• Dit artikel of een eerdere versie ervan is (gedeeltelijk) vertaald vanaf de Engelstalige Wikipedia, die onder de licentie Creative Commons Naamsvermelding/Gelijk delen valt. Zie de bewerkingsgeschiedenis aldaar.
  

细猪笼草（学名：Nepenthes tenuis）是苏门答腊特有的热带食虫植物。^[2]其种加词“tenuis”来源于拉丁文“tenuis”，意为“薄的、细的、修长的”。1957年，首次在苏门答腊岛西部一座偏远山上采集到了细猪笼草的标本。直到1994年才被正式描述，并仅于2002年重新在野外发现。在2002年之前，仅有细猪笼草的一张照片和一份干燥标本。

植物学史

1957年8月24日，威廉·梅哲首次在西苏门答腊省塔拉姆（Taram）天普河（Tjampo）附近的一个砂岩地区采集到了细猪笼草的标本。^{[注 1]}其生长于海拔约1000米的山脊上。其原生地为“明亮的亚山地森林”。^[4]

1994年，约阿希姆·那兹和安德烈亚斯·维斯图巴根据由威廉·梅哲存放于莱顿的一副标本^{[注 2]}，及在1957年采集标本时拍摄的一张黑白照片，正式描述了细猪笼草^{[注 3]}。^[1]经过多次的失败^[5]，安德烈亚斯·维斯图巴、约阿希姆·那兹、迈克尔·沙赫及其他人组成的团队在2002年末终于在野外重新发现了细猪笼草^[6][7][8]。

形态特征

细猪笼草为藤本植物。茎带棱角至菱形，较纤细，直径仅为2至3毫米。节间距为5至6.5厘米。^[1]

细猪笼草的叶片无柄，革质。其呈披针形，长5至6厘米，宽1至1.5厘米。叶尖为急尖，叶基渐狭，包住茎周长的三分之二。叶脉不明显。中脉的两侧各约有3条纵脉，其发自中脉基部的三分之一，平行延伸于叶片的外半部。羽状脉斜发，为不规则的网状，但不易辨别。笼蔓的长度约为叶片的1.5倍，可长达12厘米^[4]，厚0.5至1毫米。是否出现笼蔓圈取决于周围是否存在支持物。^[1]

细猪笼草的捕虫笼是猪笼草属中仅次于阿金特猪笼草（N. argentii）第二小的。上位笼与笼蔓的连接处形成一个宽约10毫米的弯曲。上位笼整体呈宽漏斗形，唇下缩小。通常高2.5至4.5厘米，宽1.5至2.5厘米。下位笼和上位笼都无笼翼及翼须。取而代之的是一对隆起，间距約3至5毫米。捕虫笼的整个内表面都覆盖着腺体。^[4]腺体小型，密度为每平方厘米600至800个。笼口为卵形，几乎水平。唇平展，可宽达6毫米，具唇肋，间距为1.25毫米。笼盖为窄椭圆形，无附属物，但中脉两侧各有一条明显的侧脉。笼盖一般长1.5至2.5厘米，宽0.5至0.8厘米。笼盖下表面均匀的覆盖着蜜腺。笼盖基部的后方具一根不分叉的笼蔓尾，其可长达1毫米。^[1]

细猪笼草植株的大部分都无毛，少部分可能覆盖着稀疏的毛被。细猪笼草的捕虫笼为黄绿色，且不同程度具红褐色斑点。唇为黄色至暗褐色。干燥标本为深褐色。^[1]

相关物种

在马修·杰布和马丁·奇克1997年的专著中将细猪笼草列为疑惑猪笼草（N. dubia）的同物异名时是“有一些犹豫的”。无刺猪笼草与塔蓝山猪笼草的自然杂交种（N. inermis × N. talangensis，梨形猪笼草）也被他们归入疑惑猪笼草。^[9]但查尔斯·克拉克并不赞同这个鉴定，他并不认为这三个类群属于同一个物种。^[4]

疑惑猪笼草和细猪笼草的区别相对简单。最明显的区别在于细猪笼草的捕虫笼较短，笼盖较宽且打开角度不会超过180°，而疑惑猪笼草的笼盖常常会超过180°。它们捕虫笼的颜色也不同，细猪笼草的捕虫笼外表面常具有红色的斑点，而疑惑猪笼草一般为黄色或橙色。此外，细猪笼草的唇也不如疑惑猪笼草接近圆柱形。^[4]

细猪笼草与贾桂琳猪笼草（N. jacquelineae）的区别在于细猪笼草的叶片为线形至披针形，而贾桂琳猪笼草为卵形至匙形，且细猪笼草笼盖下表面无巨型的蜜腺。贾桂琳猪笼草捕虫笼的笼盖基部还显著的缩小。此外，贾桂琳猪笼草的体型远大于细猪笼草，其捕虫笼也更发达，唇更宽，笼口几乎是水平的。^[4]

在约阿希姆·那兹和安德烈亚斯·维斯图巴对细猪笼草的描述中，包含了一个“细猪笼草于数个近似物种的显著区别”的表格：^[1]

邦苏猪笼草、疑惑猪笼草、塔蓝山猪笼草与细猪笼草之间形态特征的区别（Nerz & Wistuba (1994)）^[1] 形态特征 邦苏猪笼草 疑惑猪笼草 塔蓝山猪笼草 细猪笼草 上位笼的形状 管状至漏斗形 下半部为管状，上半部为漏斗形 下半部为管状至窄漏斗形，上半部为卵形 宽漏斗形，笼口下缩小 叶片形状 圆形 窄楔形 宽卵形 非常窄的椭圆形 上位笼的长宽比 3.3 1.9 2.3 1.75

查尔斯·克拉克写道：“细猪笼草、塔蓝山猪笼草和贾桂琳猪笼草之间的明显相似性是近期适应性辐射的一种暗示，并增加了非火山的巴里桑山脉是苏门答腊猪笼草属植物形态多样性的主要来源该观点的分量。”^[4]

2001年，查尔斯·克拉克对来自苏门答腊岛和西马来西亚的猪笼草进行了分支系统学分析，共利用了70个形态特征。以下为猪笼草进化树的“第1分支”，其相关性达51%。^[4]

  51%  

马兜铃猪笼草

  unnamed unnamed  

细猪笼草

    unnamed 95%  

疑惑猪笼草

   

无刺猪笼草

           

自然杂交种

细猪笼草生长于砂岩山脊顶部的苔藓森林或亚山地森林中。其仅出现于海拔1000米至1200米的地区。^[10][11]细猪笼草为西苏门答腊省塔拉姆西部的天普河地区特有的热带食虫植物。该地区的海拔大多在1000米以下，仅少数几处超过该高度。^[12]

细猪笼草的下位笼通常嵌于苔藓中生长。植株下部的茎也可能被苔藓覆盖，使其在野外难见其踪影。

在其原生地，细猪笼草于宽叶猪笼草（N. adnata）同域分布，并且其分布地靠近于白环猪笼草（N. albomarginata）、苹果猪笼草（N. ampullaria）、真穗猪笼草（N. eustachya）、小猪笼草（N. gracilis）、长叶猪笼草（N. longifolia）和两眼猪笼草（N. reinwardtiana）的分布地。尽管如此，仍未发现细猪笼草的自然杂交种。^[4][10]

细猪笼草已被列入《2006年世界自然保护联盟濒危物种红色名录》中，保护状况为濒危。^[13]其原生地在不久的将来可能会遭受到农业开垦放火烧山的威胁。^[4]

注释

参考文献

扩展阅读

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