Nepenthes suratensis M. Catal.

Nepenthes suratensis is a tropical pitcher plant endemic to Surat Thani Province, Thailand, where it grows near sea level in coastal savannah and grassland.^[2] It is thought to be most closely related to N. andamana.^[2][3]

The specific epithet suratensis is derived from the name of Surat Thani Province and the Latin ending -ensis, meaning "from".

Botanical history

The first known collection of N. suratensis was made by Arthur Francis George Kerr in 1927. This specimen, Kerr 13136, was collected at sea level from Kanchanadit, Surat Thani Province, Thailand. It is deposited at the Bangkok Herbarium (BK).^[2]

Nepenthes suratensis was formally described by Marcello Catalano in his 2010 book, Nepenthes della Thailandia: Diario di viaggio.^[3] The description was reviewed by Alastair Robinson, while Andreas Fleischmann provided the Latin translation.^[2] Kerr 13136 was designated as the holotype.^[2]

Description

Nepenthes suratensis is a climbing plant growing to a height of approximately 3 m. The stem is terete and up to 5 mm in diameter. Internodes are up to 6.5 cm long. The stem ranges in colour from green to red.^[2]

Leaves are sessile and coriaceous in texture. The lamina (leaf blade) is linear to lanceolate,^[3] measures up to 35 cm in length by 4 cm in width, and is around 0.5 mm thick. Its apex is acute to narrowly acuminate and it is attenuate at the base, clasping the stem for around three-quarters of its circumference. Three longitudinal veins are present on either side of the midrib, restricted to the distal quarter of the lamina. Pinnate veins are also visible, and arise obliquely from the midrib. Tendrils are up to 24 cm long and 2 mm in diameter. They are coiled in upper pitchers. The laminae are light green, whereas the midrib and tendrils vary from green to red.^[2]

Rosette and lower pitchers are either wholly ovate or ovate in the basal half of the pitcher cup and narrower above. They measure up to 15 cm in height by 5 cm in width. The hip is usually located near the middle of the pitcher, but may be completely absent in entirely ovate traps. A pair of wings (≤12 mm wide) runs down the ventral surface of the pitcher cup, bearing narrow fringe elements. The pitcher mouth is smoothly triangular and has an oblique insertion. The peristome is flattened and up to 10 mm wide, with teeth up to 1 mm long. The extent of the glandular zone of the inner surface is variable, ranging from one-third to two-thirds of the pitcher's height. The pitcher lid or operculum is broadly to narrowly ovate. It has a slightly cordate base and is often irregularly wavy at the margins. It measures up to 4.5 cm in length by 3.5 cm in width, being as large as or smaller than the pitcher orifice. The lower surface of the lid does not have any appendages, but bears numerous crater-like glands (≤1 mm in diameter), the largest of which are located around the midline. A small depression is also present on the lower surface of the lid, near the apex. An unbranched spur (≤5 mm long) is inserted near the base of the lid. On their outer surface, terrestrial pitchers are typically green to orange with red stripes, or red throughout. Red blotches are present in the waxy zone of the inner surface. The colour of the peristome is highly variable and may be green to orange or red. The lid ranges in colour from orange to red, and bears fine red streaks.^[2][4]

The tubulose to narrowly infundibular upper pitchers are similar in size to their terrestrial counterparts, measuring up to 18 cm in height by 3 cm in width. The wings, if present, are up to 3 mm wide, otherwise they are reduced to a pair of ridges. The pitcher mouth is smoothly triangular and has an oblique insertion. The peristome and lid, as well as other parts of the pitcher, are similar to those found in terrestrial traps. Aerial pitchers have a lighter pigmentation than their lower counterparts, being green to yellow on the outer surface. As in lower pitchers, red blotches are present on the waxy inner surface. Both the peristome and lid range in colour from green to yellow.^[2]

Nepenthes suratensis has a racemose inflorescence. In male plants, it reaches 70 cm in length, of which the peduncle constitutes about 50 cm and the rachis 20 cm. Around 180 flowers are produced. These are borne solitarily on pedicels measuring 3–8 mm in length. The pedicels often bear a bract in their basal half. This structure is up to 1.5 mm long and is bent inwards relative to the pedicels. The androphore is up to 3 mm long. Tepals are elliptic and up to 5 mm long by 3 mm wide. They are predominantly green with red margins. The female inflorescence is similar in structure to the male one, but differs in having a shorter rachis (10–15 cm long) and longer pedicels of 4–10 mm, which either have greatly reduced bracts or lack them altogether. It also differs in that the tepals are smaller (up to 4 mm by 2 mm) and always green.^[2]

An indumentum of orange or brown hairs (0.1–0.3 mm long) is present on the inflorescence, leaves, and stem. These hairs are caducous and consequently the lower parts of the plant are glabrous.^[2]

Like all pyrophytic Nepenthes from Indochina, N. suratensis has a well-developed rootstock.^[3]

Ecology

Nepenthes suratensis is endemic to coastal regions of Surat Thani Province, Thailand, where it is known from several localities near the town of Kanchanadit.^[1] It grows terrestrially in sandy soil and is only found in lowland areas, at altitudes of 0–200 m above sea level.^[5][6] Its typical habitat is open scrub and grassland, but it has also been recorded from the steep slopes of low hills.^[1][2]

Only three subpopulations of N. suratensis are known to be extant; a fourth subpopulation at Tha Chana has apparently been wiped out. The only subpopulation to be accurately surveyed consists of around 250 mature plants and is likely to be the largest; the other two are known only from anecdotal reports and are probably "much smaller".^[1] None of the subpopulations grow within protected areas and the species is not subject to any conservation measures. Extensive field work in the region has established the species's present range "with a high degree of confidence" and a wider distribution across Thailand is therefore unlikely.^[1] Nepenthes suratensis is listed as Critically Endangered on the IUCN Red List of Threatened Species on account of the surveyed subpopulation's predicted decline of ≥80% over the next three years as a result of planned urban development.^[1]

Nepenthes suratensis has no known natural hybrids.^[3]

Related species

Nepenthes suratensis appears to be most closely related to N. andamana.^[2][3] It is also similar to the other Indochinese endemics, including N. bokorensis, N. kerrii, and N. kongkandana.^[2]

Nepenthes suratensis can be distinguished from all of these species on the basis of its caducous indumentum, which is restricted to the upper parts of the plant and is up to 0.3 mm long. In contrast, N. andamana has a caducous indumentum up to 0.8 mm long that is restricted to the extremities of the upper stem leaves,^[7] N. bokorensis has a variable but persistent indumentum covering all vegetative and floral parts,^[8] N. kerrii has a persistent indumentum restricted to the leaf axils,^[9] and N. kongkandana has persistent hairs covering the whole plant.^[2] The lamina shape is also distinct, being linear to lanceolate.^[3] Both N. kerrii^[9] and N. kongkandana have obovate laminae, whereas those of N. bokorensis are wider (up to 8 cm versus up to 4 cm). Nepenthes bokorensis also differs in having ebracteate pedicels and a wider peristome in lower pitchers (20 mm versus 10 mm).^[2][8]

In his description of N. suratensis, Catalano also noted a number of other vegetative and floral features that separate this species from N. andamana.^[2] The male flowers of N. andamana have red tepals and the androphore reaches only 1 mm in length, whereas those of N. suratensis have green tepals with red margins and a longer androphore of up to 3 mm. Additionally, the flower bracts are bent outwards in the former and inwards in the latter. The extent of the glandular zone on the inner pitcher surface is more variable in N. suratensis, ranging from one-third to two-thirds of the trap's height. In N. andamana, it only covers around half of the inner surface. Both the lower and upper pitchers of N. suratensis have wider wings: up to 12 mm versus up to 6 mm in lower traps, and up to 3 mm versus up to 1 mm in aerial pitchers. Nepenthes suratensis also has a characteristically flattened peristome, unlike the cylindrical lip found in N. andamana. Furthermore, the pitcher lid of N. suratensis is broadly to narrowly ovate and typically somewhat smaller than the trap's orifice, whereas that of N. andamana is orbicular to broadly ovate and usually slightly larger than the mouth. The lid of N. suratensis is also distinct in that it often has irregularly wavy margins and bears a small depression under its apex. In N. suratensis, the pitcher mouth is triangular as opposed to ovate, and larger in relation to the size of the trap. The spur of this species is also shorter, being 3–5 mm long, compared to 5–7 mm in N. andamana. The upper pitchers of N. andamana often have a lighter pigmentation than those of N. suratensis, typically being whitish throughout. In addition, these traps often have a slightly lobed outer margin, a feature that is absent in N. suratensis.^[2][7]

In his Carnivorous Plant Database, taxonomist Jan Schlauer treats N. suratensis as a possible heterotypic synonym of N. thorelii.^[10]

References

• Mahavongtrakul, M. 2015. Will Nepenthes suratensis make bail? Bangkok Post, 24 June 2015.
• Mey, F.S. 2014. 'Nepenthes of Indochina', my 2010 ICPS lecture now on Youtube. Strange Fruits: A Garden's Chronicle, 3 February 2014.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Nepenthes_suratensis&oldid=1056062390"

素叻猪笼草（学名：Nepenthes suratensis）是泰国素叻府特有的热带食虫植物，其生长于沿海的热带草原。^[2]素叻猪笼草与安达曼猪笼草（N. andamana）。^[2][3]

其种加词“suratensis”来源于素叻府的名字及拉丁文词尾“-ensis”，意为“来自素叻府”。

植物学史

1927年，阿瑟·弗朗西斯·乔治·克尔在泰国素叻府干乍那迪首次采集到素叻猪笼草。该标本编号为“Kerr 13136”，存放于曼谷植物标本馆（BK）。^[2]

马尔切洛·卡塔拉诺在2001年出的书籍《泰国的猪笼草》中正式描述了其素叻猪笼草。^[3]其描述由阿拉斯泰尔·罗宾逊进行复核，并由安德烈亚斯·弗莱施曼（Andreas Fleischmann）提供拉丁翻译。^[2]编号为“Kerr 13136”的标本被指定为模式标本。^[2]

形态特征

素叻猪笼草为藤本植物，可攀爬至3米的高处。茎为圆柱形，直径可长达5毫米。节间距可长达6.5厘米。茎为绿色至红色。^[2]

叶

素叻猪笼草的叶片无柄，革质，为线形至披针形^[3]，可长达35厘米，宽至4厘米，厚度可达0.5毫米。叶尖为急尖至窄渐尖，渐狭至基部，包住茎部周长的四分之三。中脉的两侧各有3条纵脉，但仅存在于叶片的外四分之一。羽状脉可见，斜发自中脉。笼蔓可长达24厘米，直径约2毫米。叶片为浅绿色，中脉和笼蔓为绿色至红色。^[2]

捕虫笼

素叻猪笼草的下位笼通体为卵形，或下部为卵形，上部较窄，可高达15厘米，宽至5厘米。笼肩常位于下位笼的中部，也可能不存在。腹面具一对可宽达12毫米的笼翼，具窄翼须。笼口为浑圆的三角形，倾斜。唇平展，可宽达10毫米，唇齿可长达1毫米。下位笼的腺体区可位于其内表面的下三分之一至三分之二。笼盖为宽卵形或窄卵形，基部略呈心形，边缘为不规则的波浪状。其可长达4.5厘米，宽至3.5厘米，大小接近于笼口，或小于笼口。笼盖的下表面无附属物，但具大量火山口状的蜜腺，中线附近的蜜腺直径最大，可达1毫米。笼盖下表面靠近末端处有一个小凹陷。笼盖基部后方的笼蔓尾不分叉，可长达5毫米。下位笼的外表面通常为绿色至橙色且具有红色的斑点，或通体为红色。其内表面的蜡质区具有红色的斑点。唇的颜色变化多端，可为绿色至橙色或红色。笼盖可为橙色至红色，并具有红色的条纹。^[2]

素叻猪笼草的上位笼为圆柱形至窄漏斗形，大小类似于下位笼，可高达18厘米，宽至3厘米。笼翼可宽达3毫米，或缩小为一对隆起。笼口为浑圆的三角形，倾斜。唇、笼盖及其上位笼的其他部分都类似于下位笼。上位笼的颜色较下位笼浅，外表面通常为绿色至黄色。其内表面的蜡质区也与下位笼一样具有红色的斑点。唇和笼盖都为绿色至黄色。^[2]

花序

素叻猪笼草的花序为总状花序。雄性植株的花序可长达70厘米，其中总花梗可长达50厘米，花序轴可长达20厘米。共约180朵花。每个花梗带一朵花，其长3至8毫米。花梗基部常具苞片，长约1.5毫米，且向内弯曲。雄蕊柄可长达3毫米。花被片为椭圆形，可长达5毫米，宽至3毫米。其为绿色，边缘为红色。雌性花序的结构与雄性花序类似，但其花序轴较短，仅为10至15厘米，而花梗较长，为4至10毫米，且苞片大大缩小或缺失。其花被片也较小，仅长约4毫米，宽约2毫米，且始终为绿色。^[2]

其他

素叻猪笼草的花序、叶片及茎部具有橙色或棕色的毛被，其长0.1至0.3毫米。但这些毛被早落，因此植株的下部通常无毛。^[2]

与其他产自中南半岛的耐火猪笼草一样，素叻猪笼草也具有发达的地下根茎。^[3]

生态关系

素叻猪笼草是泰国素叻府沿海Kanchanadit镇附近的数个地区特有的热带食虫植物。^[4]其仅生长于海拔0至200米的砂质低地中。^[5][6]素叻猪笼草被认为与安达曼猪笼草（N. andamana）之间存在着密切的近缘关系。^[2][4][3]

素叻猪笼草现仅存三个种群；第四个位于乍纳的种群已消失。仅有一个种群经过了细致的调查，约由250个成年植株组成，并很可能是最大的种群；其他两个种群仅见零星报道，可能种群数量极小。^[4]这些种群均不位于保护区内，也没有得到任何的保护。^[4]素叻猪笼草已被列入《国际自然保护联盟濒危物种红色名录》，保护状况为极危，并预计在将来数年的城市扩展中将会有80%的素叻猪笼草消失。^[4]

尚未发现素叻猪笼草的自然杂交种。^[3]

相关物种

素叻猪笼草似乎与安达曼猪笼草之间存在着密切的近缘关系。^[2][3]其也类似于中南半岛其他特有的物种，如波哥猪笼草（N. bokorensis）、克尔猪笼草（N. kerrii）和空堪达猪笼草（N. kongkandana）。^[2]

素叻猪笼草与这些物种的区别在于其植株上部的毛被可长达0.3毫米，且早落。而安达曼猪笼草的毛被可长达0.8毫米，早落，且仅出现于上部的茎与叶^[7]；波哥猪笼草毛被的可变性较高，但其为持久性的，且覆盖于所有的营养组织和花序^[8]；克尔猪笼草的毛被仅存在于叶腋^[9]；空堪达猪笼草通体覆盖着持久的毛被^[2]。它们叶片的形状也不同，素叻猪笼草的为线形至披针形。^[3]而克尔猪笼草和空堪达猪笼草的叶片为倒卵形；波哥猪笼草的更宽大，可宽至8厘米。此外，波哥猪笼草的花梗无苞片，且下位笼的唇更宽，可达20毫米。^[2][8]

在素叻猪笼草的描述中，马尔切洛·卡塔拉诺也注意到了许多与安达曼猪笼草不同的形态特征：^[2]

素叻猪笼草与安达曼猪笼草之间形态特征的区别（M. Catal 2010）^[2][7] 形态特征 素叻猪笼草 安达曼猪笼草 花被片 绿色 红色 雄蕊柄 仅长约1毫米 可长达3毫米 苞片 向内弯曲 向外弯曲 捕虫笼内表面蜡质区 下三分之一至三分之二 下二分之一 下位笼笼翼 12毫米 6毫米 上位笼笼翼 3毫米 1毫米 唇 特别平展 圆柱形 笼盖 宽卵形至窄卵形，通常小于笼口 圆形至宽卵形，通常大于笼口 笼口 三角形 卵形 笼蔓尾 3至5毫米 5至7毫米 上位笼的颜色 较浅 通常为白色

在食虫植物数据库中，分类学家简·斯洛尔（Jan Schlauer）将素叻猪笼草列为高棉猪笼草（N. thorelii）的疑似同物异名。^[10]

参考文献

扩展阅读

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