First record of functional underground traps in a pitcher plant: Nepenthes pudica (Nepenthaceae), a new species from North Kalimantan, Borneo
Martin Dančák, Ľuboš Majeský, Václav Čermák, Michal R. Golos, Bartosz J. Płachno, Wewin Tjiasmanto
Summarized by Michael Hallinan
What data were used? 17 different specimens of a new species of pitcher plant (Nepenthes pudica) were examined from 5 different sites across the North Kalimantan province of Indonesia. This region is mountainous and covered with extensive rainforest. The specimens were photographed, sampled, and then fixed in ethanol or dehydrated in preparation for further evaluation. In addition to these specimens, prey samples were also collected, including earthworms, insects, and insect larvae from inside the plants themselves. These were fixed in formaldehyde and further documented similar to the plant itself.
Methods: The specimens went through three main stages of examination. First, the plants were photographed and compared to drawings and descriptions of other species within the genus Nepenthes. Next, the trap parts (used by the carnivorous plant to trap and collect prey) were examined under an electron microscope. Lastly, some of the traps were poured out and found to consist of insects, mites, and ticks. This content was identified and signs of digestion were documented, allowing the content to be labeled as either prey, or just organisms that live in the sediment and were unintentionally collected.
Results: Typically the genus Nepenthes catches prey through a pitfall trap which has their prey fall into a pitcher-shaped cavity formed by a cupped leaf, where the plant then breaks them down through digestive juices. However, these traps are usually above ground or in water, with this trait only found in other genera such as Genlisea, Philcoxia, and Utricularia, though they use different entrapment strategies. The discovered species (Nepenthes pudica) features underground pitchers, where it catches and consumes prey such as mites, leaf litter-inhabiting beetles and ants. It is the first known pitcher plant species to use pitfall traps within the subterranean environment, containing traps of comparable size to the rest of the genus despite its subterranean nature. Typically, the pressure needed to form a cavity in soil is unsuitable for pitchers like these, which not only makes this find unique, but it also challenges our understanding of carnivorous plant feeding strategies.
Why is this study important? This study is extremely important as identification is essential for protection. If we are more aware of which different species exist, we can better understand relative biodiversity as well as focus our conservation efforts. The discovery of this plant in particular allows a little bit more insight into understanding evolutionary adaptations of carnivorous plants which can potentially be applied to other plants within Indonesia’s ecosystem as well as carnivorous plants worldwide.
The big picture: 17 specimens of a new species of carnivorous plant were collected and further examined. Through a series of comparisons to known species within the genus as well as analysis of its prey and structure, it was determined to be a new species especially as a result of its unique underground traps. The traps typically seen within this genus of plants appear above ground or in water, which makes this species unique. This discovery allows us to better understand biodiversity in the region and gives us new insights into how we need to approach conservation.
Citation: Dančák M, Majeský Ľ, Čermák V, Golos MR, Płachno BJ, Tjiasmanto W (2022) First record of functional underground traps in a pitcher plant: Nepenthes pudica (Nepenthaceae), a new species from North Kalimantan, Borneo. PhytoKeys 201: 77-97. https://doi.org/10.3897/phytokeys.201.82872