Botanists have described the first predatory plant with underground hunting pitchers. The species, called nepenthes bashful, grows only in the north of Borneo and hunts mainly ants. Probably, moving the pitchers underground allows this plant not to compete with other nepenthes or survive droughts.

Nepenthes (Nepenthes) are one of the most famous hish plants. They are easily recognized by their characteristic leaves in the shape of pitchers, which are used for hunting insects and other small animals. According to botanists, the genus nepenthes includes more than 160 species distributed in South and Southeast Asia, Australia and the islands of the Indian and Pacific Oceans.

Nepenthes are the most diverse on the island of Borneo. Among the approximately 40 species registered here, there are several particularly bizarre ones. These include, for example, N. rajah with hunting pitchers up to 41 centimeters high and up to 20 centimeters wide, which is considered one of the largest predatory plants in the world. And N. lowii, also native to Borneo, entered into a kind of relationship with Tupaia Tupaia montana. Plants attract animals with a sweet secret, which is released by the inside of the lid. During feeding, tupaya sits on a jug and defecates directly into it, providing nepenthes with the necessary minerals.

A team of botanists led by Martin Dančák from Palacki University managed to replenish the list of Borneo flora with another very unusual species of nepenthes. In February 2012, scientists surveyed the mountain rainforests in the north of the Indonesian part of the island, at an altitude of 1100-1300 meters above sea level. Here they found nepenthes belonging to a previously unknown species. In total, seventeen specimens were found on five sites located nearby from each other.

Like all nepenthes, representatives of the new species have pitchers for hunting small animals. However, unlike all known relatives, they have these traps located underground — in cavities between tree roots, in soil, leaf litter or under a layer of moss. Strong and thick-walled purple-red water lilies grow on chlorophyll-free underground shoots and reach 7-11 centimeters in length and 3-5.5 centimeters in width. At the same time, aboveground pitcher bushes are rarely formed in this type of nepenthes. Since most of the hunting leaves of the new nepenthes species are hidden from prying eyes underground, Danchak and co—authors decided to give it the Latin name Nepenthes pudica - that is, nepenthes bashful.

After studying the contents of five underground and one aboveground pitchers, the researchers found 1,785 invertebrate individuals belonging to 40 taxa. Among the prey of the shy nepenthes, species inhabiting the forest floor and soil prevailed: ants from the subfamily Myrmicinae (they turned out to be the most frequent victims of predatory plants), mites from the family Oribatidae and beetles from the families Scydmaenidae, Pselaphidae, Liodidae and Carabidae. In addition, as in the pitchers of other nepenthes, in the liquid of the pitchers N. invertebrate symbionts have been found in pudica, primarily mosquito larvae, nematodes and roundworms.

Nepenthes bashful is the first known predatory plant with underground pitchers. However, this is not the first species of predatory plants that has adapted to underground hunting. Underground trapping organs of other types have previously been described for some representatives of the genera Genlisea, Philcoxia and Utricularia. However, the traps of these plants are very small and suitable only for small and microscopic prey, and the pitchers of N. pudica are large enough to hunt animals of the usual size for Nepenthes.

Apparently, underground pitchers allow the shy nepenthes to avoid competition with other nepenthes or help to survive difficult periods, for example, drought. At the same time, it seems that this is not the only kind of Nepenthes with such an unusual hunting strategy. In 2019, another population of Nepenthes with underground pitchers was discovered in eastern Borneo. Unlike N. pudica, they grow in lowland forests. Perhaps these nepenthes represent a separate species.

According to Danchak and his colleagues, the entire range of the new species does not exceed four square kilometers and is located outside protected areas. This makes it extremely vulnerable to deforestation. The authors propose to assign it the conservation status of a species on the verge of complete extinction (Critically Endangered, CR).

The article was published in the journal PhytoKeys
PHOTO: Underground hunting leaves of Nepenthes pudica © Martin Dančák et al. / PhytoKeys, 2022

Source: Sergey Kolenov,

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