Martin Cheek, a senior botanist at Kew, describes how 12 new species of carnivorous pitcher plants from the Philippines were discovered among Kew’s 7 million herbarium specimens.
Carnivorous plants such as Nepenthes (pitcher plants), which attract, trap, digest and assimilate animals, while looking bizarrely beautiful to humans, have long attracted attention from both scientists and the cultivators of tropical plants. Numerous doctorates have been completed on plant-animal interactions in several species of Nepenthes, and every year recently, one surprising new discovery after another has been made on the mechanisms that these species have evolved in order to obtain nutrients from animals.
I could write pages on the subject! Yet, I was completely unaware, until I read a recent article by Dona Paranayil in the Independent on Sunday, that there are numerous new, important commercial engineering applications based on the construction of the slippery surfaces of these plants. And only in the last year did I realise that, apart from the commercial market for live Nepenthes species for collectors, there is an even bigger horticultural market in artificial hybrids, which are spectacular and more vigorous in growth than the wild species. (I still campaign to have them removed from Kew’s live science collections - if you are trying to work out one species from another as we taxonomists do, it does not help to have hybrids to contemplate).
Nepenthes ultra, one of 12 new species of carnivorous pitcher plant, photographed in the wild in Luzon, Philippines. (Image: Pieter Pelser, Phytoimages)
Given the value to humanity of Nepenthes, in terms of the market in live plants, commercial applications for 21st century needs, and perhaps relief from boredom, it seems especially regrettable that species should be going extinct in the Philippines. Most of the 12 new species described in 2013 are threatened and our Nepenthes extincta, published just before Christmas, probably IS extinct already (see the most recent issue of the European Journal of Taxonomy), due to ongoing open-cast mining for nickel which is used in making the stainless steel that we all use.
Destruction of natural habitat in the Philippines has been huge. In 1925 two-thirds of forest was considered intact (Sohmer and Davis, 2007) while 75 years later it was estimated that only 3% of primary vegetation survived (Myers et al., 2000). Sohmer and Davis estimate that species extinction levels due to habitat destruction in one representative, mainly forest, genus, Psychotria (Rubiaceae), has been between 9 and 28% so far, and habitat destruction continues apace, caused by oil palm, pineapple and other plantations, as well as open cast mining.
The description of Nepenthes robcantleyi in 2011 was based on plants known from only a single location in the Philippines, where the forest has since been cut down. (Image: Rob Cantley)
Matthew Jebb (National Botanic Garden, Glasnevin, Ireland) and I began collaborating on Nepenthes taxonomy in the 1980s, as a side interest to our doctoral research lines. He had been inspired by seeing them in the field in New Guinea while working on ant plants, while, apart from Madagascar,I had only seen them in glasshouses at that point. In working towards completing a World Monograph of the genus, we have collaborated on a series of, so far, about 20 research publications which delineate the species (see Reference section below for further details).
When we completed the Flora Malesiana account for the family Nepenthaceae in 2001, we only recognised 12 species from the Philippines. It was a surprise that, in the following ten years, intrepid enthusiasts of the genus from Japan, the UK, Germany, France, Australia and the USA, heroically climbing mountains never before visited by a botanist, uncovered another 12, some extraordinarily spectacular. Since these enthusiasts only sought Nepenthes, one can only guess at what other scientifically unknown organisms were overlooked on these trips!
The 12 new species we published in 2013, however, were all discovered in the specimen cupboards of the Kew Herbarium. A fresh look at variation in specimens of what had been considered one species, Nepenthes alata, in Luzon, resulted in 2012 in the delimitation of two clear-cut taxa, suggesting that a closer look at material from other islands in the Philippine archipelago was in order.
The Herbarium at Kew holds over seven million plant specimens, and the 12 new Nepenthes species lay undiscovered for years.
Prompted by Kew’s SE Asian specialists Tim Utteridge and Rogier de Kok, and by Rubiaceae specialist Aaron Davis, who had worked on a Philippines group, Herbarium specimen loans were sought and received from some, on the face of it, unlikely herbaria for Philippine plants. The Botanical Research Institute of Texas, The University of California, The Field Museum at Chicago, the Berenice Bishop Museum in Hawaiii (among others) all kindly provided loans. Initially I was sceptical of the value of these actions, until the specimens arrived, consignment by consignment. When grouped together at Kew with our own material, and material previously loaned to Kew from other herbaria, such as Leiden (the main herbarium for SE Asia), it quickly became obvious that distinct taxa were present that were completely unknown to science.
Herbarium specimen of Nepenthes kitanglad, known only from Mt Kitanglad in Bukidnon Province, Philippines and assessed as Critically Endangered as part of its description as a new species in 2013.
No other Nepenthes specialist had ever seen most of these specimens, yet several had been collected as long as 100 years ago! Each herbarium had material that was not duplicated at other herbaria. In analysing the specimens, in addition to gross morphology, microscopic examination of the lower surface of the lid of the pitcher (an important part of the trapping mechanism) and for the first time in detail, the precise trichome complements of the surfaces of the pitchers, leaf-blades and stems, proved vital to delimiting the taxa. Inflorescence characters were less useful, perhaps because Nepenthes have only generalised insect pollinators, compared with the often specific animal groups that their pitchers target.
The outcome of the detailed examination of taxonomically useful characters in these specimens was the astounding discovery that 12 new species had lain undiscovered amongst Kew’s collections. All twelve were formally named and described in 2013 in the publications detailed below.
Are there more unknown species out there? Almost certainly!
- Martin -
- Cheek, M. & Jebb, M. (2013). Recircumscription of the Nepenthes alata group (Caryophyllales: Nepenthaceae), in the Philippines, with four new species. European Journal of Taxonomy 69: 1-23. Available online
- Cheek, M. & Jebb, M. (2013). Identification and typification of Nepenthes blancoi, with N. abalata sp. nov. from the western Visayas, Philippines. Nordic Journal of Botany 31: 151-156. Available online
- Cheek, M. & Jebb, M. (2013). Nepenthes alzapan (Nepenthaceae), a new species from Luzon, Philippines. Phytotaxa 100: 57-60. Available online
- Cheek, M. & Jebb, M. (2013). Nepenthes ramos (Nepenthaceae), a new species from Mindanao, Philippines. Wildenowia 43: 107-111. Available online
- Cheek, M. & Jebb, M. (2013). Nepenthes samar (Nepenthaceae), a new species from Samar, Philippines. Blumea 58:82-84. Available online
- Cheek, M. & Jebb, M. (2013). Typification and redelimitation of Nepenthes alata with notes on the N. alata group, and N. negros sp. nov. from the Philippines. Nordic Journal of Botany 31: 616-622. Available online
- Cheek, M. & Jebb, M. (2013). Nepenthes ultra (Nepenthaceae), a new species from Luzon, Philippines. Blumea 58: 241-244. Available online
- Cheek, M. & Jebb, M. (2013). The Nepenthes micramphora (Nepenthaceae) group, with two new species from Mindanao, Philippines. Phytotaxa 151: 25-34. Available online
- Myers, N., Mittermeier, R.A. Mittermeier, C.G., da Fonseca, G.A.B. & Kent, J. (2000). Biodiversity hotspots fr conservation priorities. Nature 403: 853-858. Available online
- Sohmer, S.H. & Davis, A.P. (2007). The genus Psychotria (Rubiaceae) in the Philippine Archipelago. Botanical Research Institute of Texas, Fort Worth, USA.
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