Three new species of Pitcher Plants from the Philippines.

Pitcher plants of the genus Nepenthes are known from Malaysia (where the genus reaches its maximum diversity) as well as Madagascar, Seychelles, Sri Lanka, northeast India, Indochina, Solomon Islands, New Caledonia, Australia and the Philippines. All the Philippine species are considered to be at risk due to deforestation, as the islands suffered a rapid loss of forests in the twentieth century (around 75% of the indigenous forest was undisturbed in 1925, but by the end of the century only 3% remained), and since most Nepenthes species have limited geographical ranges and are intolerant of disturbance, it is quite likely that many species have become extinct without ever being recorded.

In a paper published in the journal Blumea on 11 December 2014, Martin Cheek of the Royal Botanic Gardens at Kew and Mathew Jebb of the National Botanic Gardens at Glasnevin, describe three new species of Nepenthes from Sibuyan and Mindanao Islands in the Philippines.

The first new species described is named Nepenthes armin, in honour of Armin Rios Marin, a Municipal Councillor on Sibuyan and former official of the World Wildlife Fund, who on 3 October 2007 was shot and killed by a mining official while leading a community demonstration against forest clearances by the mining industry. Nepenthes armin is a climbing plant reaching 5 m in height. It produces elongate leaves up to 17.5 cm in length, with tendrils at their tips upon which the pitchers develop. The pitchers are green with a faint purple mottling and can reach 16 cm in depth.

The species was found growing in gallery forest on ultramafic rock (expand) at an altitude of 750 m. Only three individuals were found at three separate sites; several searches for further specimens by pitcher plant enthusiasts have failed to find any more plants, nor was it found by earlier expeditions to the area in the early twentieth century. The area where it grows has been partially cleared for lowland agriculture. As such the species is assessed to be Critically Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Nepenthes armin. (a) Habit, male inflorescence, and upper pitchers (detached); (b) upper pitchers. Scale bar is 5 cm. Cheek & Jebb (2014).

The second new species described is named Nepenthes tboli, after the T’boli People, who live in the area where it was discovered. This is a shrub or climber reaching at least 50 cm in height, producing leaves up to 16 cm long, with tendrils at the tips upon which the pitchers grow. The pitchers are 11.5-17.5 cm deep.

Only two specimens of the plant were found, growing on open grassland by Lake Parker in South Cotabato Province on Mindanao. As such the species is assessed to be Critically Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species, though Cheek and Jebb note that the plants were found close to the botanically poorly known Tiruray Highlands, so there is hope of undiscovered populations being discovered.

Nepenthes tboli. Habit with upper pitchers and infructescence. Scale bar is 5 cm. Cheek & Jebb (2014).

The third new species described is named Nepenthes zygon, meaning ‘yoked’ or ‘coupled’, due to this species close relationship with Nepenthes mindanaoensis. This is a terrestrial climber reaching 2-3 m tall, possibly capable of rooting on stunted trees in cloud forest. Leaves can reach 30 cm in length, lower pitchers can reach 14 cm, upper pitchers 25 cm. Pitchers are covered with a white waxy layer and have red-to-purple stripes and flecks.

Nepenthes zygon has been observed growing in submontane mossy forest along ridges of non-ultramaffic rock, at altitudes of 1500-1875 m above sea level, on Mounts Masay and Pasian and possibly Hibok-Hibok. Unfortunately much of the forest on Mount Pasain has recently been clear-cut, leading to concerns that the species might be extinct there. The population at Mount Masay faces no such threat at the current time; that at Hibok-Hibok has yet to be confirmed. The species is assessed to be Critically Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Nepenthes zygon. (a) Habit, climbing stem with male inflorescence and upper pitcher; (b) upper pitcher, not yet fully opened; (c) lower pitcher. Scale bars are 5 cm. Cheek & Jebb (2014).

See also…

How a Marsh Pitcher Plant catches its diner.

Marsh, or Sun, Pitcher Plants (Sarraceniaceae) are Carnivorous Plants growing in nutrient poor marshy conditions in South America. They have the tubular leaves of all Pitcher Plants, but lack the lids of many such plants (Pitcher Plants are not a true taxonomic...

Catapulting tentacles in a sticky Carnivorous Plant.

Sundews (Drosera spp.) are a widespread group of Carnivorous Plants, found on every continent except Antarctica. They are able to live on extremely nutrient...

Ants in the diet of a Cambodian Pitcher Plant.

Pitcher Plants, or Monkey-cups, are carnivorous plants that trap Insects inside a deep, fluid-filled trap, where their bodies are then digested, providing valuable nutrients for the plants, which are thereby able to survive on very nutrient-poor soils. They are not a true...

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How a Marsh Pitcher Plant catches its diner.

Marsh, or Sun, Pitcher Plants (Sarraceniaceae) are Carnivorous Plants growing in nutrient poor marshy conditions in South America. They have the tubular leaves of all Pitcher Plants, but lack the lids of many such plants (Pitcher Plants are not a true taxonomic group, but the result of convergent evolution; the different groups of Pitcher Plants are not closely related), nor do they produce their own digestive enzymes, being reliant instead on symbiotic Bacteria to digest their prey.

In a paper published in the Proceedings of the Royal Society: Series B, Biological Sciences on 19 December 2012, Ulrike Bauer or the Department of Plant Sciences at the University of Cambridge, Mathias Scharmann of the Department of Animal Ecology and Tropical Biology at the University of Würzburg, Jeremy Skepper of the Department of Physiology, Development and Neuroscience at the University of Cambridge and Walter Federle of the Department of Zoology at the University of Cambridge, examine the way in which the Marsh Pitcher Plant, Heliamphora nutans, captures its prey.

Marsh Pitcher Plant, Heliamphora nutans, growing at Kew Gardens. Wikipedia.

Heliamphora nutans secretes nectar from the inner surface of an appendage on the upper part of the leaf known as a nectar spoon. Beneath this the inner surface of the upper part of the leaf, called the pubescent zone, is covered with a dense carpet of inward-pointing hairs, thought to be associated with prey capture. Beneath this is a smooth area known as the glandular zone, which contains the water in which the plant digests its prey; this does have some hairs at the bottom, though they are different from those on the upper wall.

The anatomy of Heliamphora nutans. Bauer et al. (2012).

Bauer et al. allowed Ants to access the plants under controlled conditions at Kew Gardens. They found that while the leaves were dry the Ants were able to move over the surface unhindered, but once they were exposed to moisture the hairs on the inner surface of the leaves trapped a layer of water, which caused ants to aquaplane into the trap.

Video showing the fate of Ants on wet and dry leaves of Heliamphora nutans. Bauer et al. (2012), supplementary material.

See also Catapulting tentacles in a sticky Carnivorous Plant, Four new species of Leafhopper from Southern Africa, Two new species of Ant from northwest India, Ants in the diet of a Cambodian Pitcher Plant and New species of Ghost Ant named after Edward O. Wilson.

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Ants in the diet of a Cambodian Pitcher Plant.

Pitcher Plants, or Monkey-cups, are carnivorous plants that trap Insects inside a deep, fluid-filled trap, where their bodies are then digested, providing valuable nutrients for the plants, which are thereby able to survive on very nutrient-poor soils. They are not a true taxonomic group, with different groups of Pitcher Plants apparently having evolved separately from Flypaper Trap Plants, which trap and digest Insects using sticky secretions from their leaves (Flypaper Trap Plants are also polyphyletic; they have evolved separately a number of times).

Pitcher Plants of the genus Nepenthes are found across southern Asia, Indonesia, New Caledonia and Australia, as well as in the Seychelles and Madagascar. They are not thought to be closely related to any other group of Pitcher Plants. 

Previous studies of Plants in the genus Nepenthes have found that Ants form a major part of their diet, but have not looked closely into which Ants are being consumed, either because the remains are often two badly digested for taxonomic identification, or because the scientists involved lacked sufficient expertise in Ant taxonomy. 

In a paper published in the July 2012 edition of the Cambodian Journal of Natural History, Shingo Hosoishi and Sang-Hyung Park of the Institute of Tropical Agriculture at Kyushu University, Seike Yamane of the Department of Earth & Environmental Sciences at the Faculty of Science at Kagoshima University, and Kazuo Ogata, also of the Institute of Tropical Agriculture at Kyushu University present the results of a survey of Ants in the diet of Nepenthes bokorensis, a Pitcher Plant found only on Mount Bokor in southern Cambodia, living on sandy soils at altitudes of between 800 and 1080 m.

A specimen of Nepenthes bokorensis growing in the Phnom Bokor National Park. Don Pirot/Rutgers University.

Hosoishi et al. split a section of forest margin in the Phom Bokor National Park, at an altitude of 900 m,  into 3 transects, 0-5 m, 5-10m and 10-15 m from a forest edge. Each transect contained 10 Pitcher Plants, for a total of 30 individuals. Ants were collected from the traps of these pitcher plants in December 2012.

Ten species of Ant were collected, belonging to nine genera; eight from the transect nearest to the forest edge, ten from the middle transect and six from the outer transect. Species diversity did not significantly vary between the transects.

The most abundant species of Ant, making up 40% of the individuals collected was identified as Polyrhachis (Myrma) sp. These are large Ants, and may contribute significantly to the nutritional requirements of the Pitcher Plants.

Polyrhachis (Myrma) sp. The scale bar is 0.5 mm. Hosoishi et al. (2012).

The next most abundant species was Dolichoderus thoracicus, a widespread southeast Asian species often used as a biological pest-control agent (i.e. often introduced to new areas by humans), due its ability to keep down the numbers of some Insects considered agricultural pests. Dolichoderus thoracicus is highly adaptable, and can nest both on the ground and in the branches of trees.

Dolichoderus thoracicus. The scale bar is 0.5 mm. Hosoishi et al. (2012).

The third most abundant species was identified as Camponotus (Tanaemyrmex) sp., another large species, likely to make a significant contribution to the Pitcher Plant's diet.

Camponotus (Tanaemyrmex) sp., minor worker (there are larger castes of this Ant). The scale bar is 0.5 mm. Hosoishi et al. (2012).

Significant numbers of Ants belonging to the Cardiocondyla wroughtonii complex (complex implies scientists are uncertain of these Ants are all the same species, though they are clearly closely related). These are invasive introduced Ants from tropical Africa, and while they are not as harmful as some introduced Ant species, do appear to be spreading rapidly in southeast Asia. Hosoishi et al. suggest that if this Ant is equally vulnerable to other species of Pitcher Plant, then sampling these plants could be a good way to monitor their spread.

An Ant from the Cardiocondyla wroughtonii complex. The scale bar is 0.5 mm. Hosoishi et al. (2012).

See also New species of Ghost Ant named after Edward O. Wilson, and Evidence of fungal parasites modifying the behavior of ants from the Eocene Messel Shale.

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