Drosera albonotata: A new species of Pygmy Sundew from Western Australia.

Sundews, Droseraceae, are a highly successful group of Carnivorous Plants found around the globe. Like other forms of Carnivorous Plants, they can grow on very poor soils by supplementing their nutritional intake by feeding on animals, generally Insects or other small Invertebrates. Sundews capture their prey using specialised leave, which are covered in tentacles, each of which is tipped with a blob of sticky glue, that adheres to the prey animal preventing it from escaping. As the animal struggles it is likely to encounter multiple tentacles, all of which will stick to it until it becomes wrapped and immobilised, enabling the plant to digest it. The Pygmy Sundews, Drosera spp., are the largest single genus of Carnivorous Plants known, with over 250 described species, over 110 of which come from Australia. The genus has a Southern Hemisphere distribution, being found in arid regions of Brazil, South Africa and Australia. These plants are distinguished by small leaves and orange flowers.

In a paper published in the journal Phytotaxa on 6 April 2018, Alastair Robinson of Southbank in Victoria, Australia, Adam Cross of the Centre for Mine Site Restoration of the Department of Environment and Agriculture of Western Australia, Manfred Meisterl of Vienna in Austria, and Andreas Fleischmann of the Botanische Staatssammlung München, describe a new species of Pygmy Sundew from Western Australia.

The new species is named Drosera albonotata, meaning ‘white marked’ in reference to the white markings on the petals of this species. The new species is a perennial herb forming rosettes 0.8-2.5 cm in diameter, with 6-18 active leaves. The leaf rosettes start out flat to the soil, but as the plant grows each season’s growth overlays the previous, so that in some plants it sits on top of a 4 cm layer of withered leaves. Flowers are born in September and October, on a stem that rises 3.3-14.2 cm above the plant. Each stem can bear up to 15 orange, five-petaled flowers, 16-25 cm in diameter, each petal having two white markings at its base, that form a collar around the centre of the flower.

Living plants photographed in situ, showing left a flowering plant, and right a mature rosette. Alistair Robinson in Robinson et al. (2018).

The plants were initially found growing in the Wandoo National Park, and subsequently found in the shires of Northam, York and Quairading, and possibly Cunderdin, Tammin and Kellerberrin (there was some difficulty in establishing the full range of the plants, as many were growing in agricultural areas, and the study period overlapped with the Wheat harvest), all within the western Wheatbelt region of Western Australia. They favoured woodland on ridges and low rises, generally on gravelly slopes and pale yellow to brown sandy clay-loam soils with a moderate to dense shrub understorey. Several observations were made of a Scarab Beetle of the genus Liparetrus visiting the flowers of Drosera albonotata and emerging covered in pollen. This is unsurprising, as Beetles of this genus are known to pollinate several Sundew species. The species is known from less than ten locations, each with about 25-150 individuals, and all within an area of less than 2000 km², and the species is clearly at risk from expanding agriculture in the region. As such Drosera albonotata is assessed to be Vulnerable under the terms ofthe International Union for the Conservation of Nature’s Red List of Threatened Species.

A pollinator of Drosera albonotata, identified as a Melolonthid (Scarabaeidae) possibly in the genus Liparetrus. Alistair Robinson in Robinson et al. (2018).

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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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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 poor soils by capturing Insects and other small Arthropods using tentacles on their leaves which excrete glistening glue drops that resemble dew, then digesting them using enzymes excreted from pores on the leaves. Several species exhibit limited movement, with tentacles and sometimes whole leaves bending to enfold struggling prey animals, though the mechanisms behind this are not well understood.

In a paper published in the journal PLoS One on 26 September 2012, a team of scientists led by Simon Poppinga of the Plant Biomechanics Group at the University of Freiburg study the movements of Drosera glanduligera, a common southern Australian Sundew, which catapults prey animals into the central part of its feeding leaves using non-sticky 'snap-tentacles' around the outer part of the leaves, then enfolds them with the shorter glue tentacles.

Video showing Drosera glanduligera capturing Fruit Flies. Poppinga et al. (2012).

The trap-leaves of Drosera glanduligera. (A) Wild growing plant, showing concave leaves and peripheral, non-sticky, snap tentacles. (B) Individual leaf, showing distribution of tentacles. (C) Fruit-fly trapped by leaf, which has enfolded around it. Poppinga et al. (2012).

Poppinga et al. found that the tentacles moved by contracting the cells on the inner (adaxial) side of the tentacles, and at the same time expanding those on the outer (abaxial) side, achieving a rapid folding towards the center of the leaf. This was not a repeatable movement, as in the muscle of an animal, or even the closing of the leaf of a Venus Fly Trap (Dionaea muscipula); once a tentacle had contracted once it could not be used again (this is similar to the sudden movements used by some plants to launch seeds). The movement of the tentacles was dependent on a number of environmental factors, with faster movements in warmer conditions. Plants which were too cool or suffering from dehydration do not move very fast.

The anatomy of the snap-tentacles. (A) SEM micrographs; left,  entire tentacle; right, detail of the zone where folding occurs, with arrows indicating the cells which compress. (B) Transverse section of the hinge zone. Poppinga et al. (2012).

Overlaid time lapsed photographs of the tentacle motion, taken at 5 ms intervals. Poppinga et al. (2012).

See also Ants in the diet of a Cambodian Pitcher Plant.

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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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