Researchers exploring Ecuador’s Amazon rainforest thought they had spotted a small mushroom clinging to the underside of a leaf during a night survey. A closer look revealed something far stranger. It was a spider that had disguised itself so convincingly as a parasitic fungus that it fooled even experienced scientists.The newly identified species, named Taczanowskia waska, is the first known spider ever documented to mimic a fungus that infects spiders. The discovery, made by an international team of researchers including scientists from the Leibniz Institute for the Analysis of Biodiversity Change (LIB), has been published in the journal Zootaxa.The spider was discovered in the Llanganates-Sangay Corridor in the Ecuadorian Amazon, a region recognised as one of the most biologically rich places on Earth. During a nighttime field expedition, researchers initially believed they were looking at a mushroom growing beneath a leaf before realising it was a living spider.The mistaken identity itself became one of the strongest clues that the species had evolved an unusually effective disguise.
A spider that looks like a parasitic fungus
Unlike most spiders that blend into bark, leaves or flowers, Taczanowskia waska has evolved to resemble the fruiting body of fungi belonging to the genus Gibellula. These fungi are well known because they grow on spiders after infecting and killing them.The resemblance is striking.The spider has pale colouring and elongated structures extending from its abdomen, giving it the appearance of fungal growth. It also behaves in a way that strengthens the illusion. Instead of actively moving around in search of prey, it remains completely motionless on the underside of leaves, precisely where Gibellula fungi are commonly found in the rainforest.According to the researchers, the combination of appearance and behaviour points to a highly specialised form of mimicry that has never before been documented in spiders.The disguise may help the spider avoid predators by making it appear to be something they would ignore. At the same time, remaining unnoticed could allow it to ambush unsuspecting prey more effectively.
A first for science
The study describes Taczanowskia waska as the first recorded example of a spider mimicking a parasitic fungus that infects its own kind.That makes the discovery significant beyond the description of a new species. It also provides scientists with fresh evidence of how mimicry can evolve in nature and the different ecological roles such adaptations may serve.Researchers say the finding expands current understanding of survival strategies among spiders and raises new questions about how similar forms of mimicry may have evolved in other rainforest species that have yet to be studied.The spider belongs to the genus Taczanowskia, a group considered both rare and poorly understood. Members of the genus are seldom encountered in the wild, leaving much of their ecology and behaviour unknown.
An unexpected discovery with help from citizen scientists
The discovery did not begin in a laboratory or during a planned search for a new species.Instead, it started with an observation uploaded to the citizen science platform iNaturalist. What observers believed to be a mushroom caught the attention of users on the platform, who recognised that the unusual object might actually be a spider.That online observation prompted scientists to investigate further, eventually leading to the formal identification of a species that had never before been described.Researchers say the case shows how members of the public can play an important role in biodiversity research, particularly in remote regions where many species remain undocumented.Nadine Dupérré from the Museum of Nature Hamburg at LIB contributed to the research by examining reference specimens held in scientific collections and helping classify the newly discovered spider.“Finds like these demonstrate the value of scientific collections. They enable us to classify new species and compare them with historical specimens. Combined with international collaboration and citizen science, this opens up new opportunities for researching biodiversity,” explains Nadine Dupérré.
Why mimicking a fungus is so unusual
Mimicry is common in nature, but this case stands out because the spider is not copying a plant, leaf or harmless object. It is imitating a parasitic fungus that infects other spiders.That fungus belongs to the genus Gibellula. It is known for growing on spiders after infection, eventually producing pale, stalk-like structures that emerge from the host’s body. These fungal growths are often found attached to the undersides of leaves in humid rainforest environments.The resemblance created by Taczanowskia waska is close enough that researchers initially failed to recognise it as an animal during fieldwork. The spider’s body shape and pale, fungus-like extensions closely match the appearance of infected spiders covered by Gibellula.Its behaviour adds another layer to the disguise. By staying motionless in the same positions where infected spiders are usually found, it reinforces the illusion that it is not alive in the usual sense.Researchers believe this combination of physical form and behaviour may serve two purposes. It may help the spider avoid being detected by predators that learn to ignore fungus-infected prey. It could also allow it to ambush insects that come too close, mistaking it for something inedible.
A rare genus still largely unknown
The spider belongs to the genus Taczanowskia, a group that remains poorly studied. Scientists rarely encounter members of this genus in the wild, which has left major gaps in understanding their behaviour, distribution and ecological role.Because of this, each new finding adds important detail to a group that is still largely undocumented. The discovery of a species with such a specialised form of mimicry has raised further questions about how diverse survival strategies within this genus might be.
Found through citizen observation
The chain of discovery began far from formal research settings. An image uploaded to iNaturalist, a citizen science platform, showed what appeared to be a mushroom on a leaf in the Ecuadorian rainforest.Users on the platform questioned that interpretation, suggesting it might instead be an animal. That discussion prompted closer scientific scrutiny, eventually leading to field confirmation and formal classification of a new species.The case has reinforced the growing role of citizen science in biodiversity research, particularly in remote ecosystems where scientific surveys are limited.
Amazon biodiversity and scientific collaboration
The spider was found in the Llanganates-Sangay Corridor, a stretch of Ecuadorian Amazon rainforest known for its high levels of biodiversity and limited scientific exploration. The region continues to yield new species across different groups of organisms, from insects to plants and fungi.The research team involved in the discovery included scientists from the Leibniz Institute for the Analysis of Biodiversity Change (LIB), alongside international collaborators. Museum collections also played a key role, helping researchers compare specimens and confirm the spider’s classification.Nadine Dupérré from the Museum of Nature Hamburg at LIB contributed by examining preserved specimens and assisting in the taxonomic work that confirmed the species as new to science.
Publication details
The findings were published in the journal Zootaxa in 2026 under the title: “The Cordyceps spider”: Taczanowskia waska sp. nov. (Araneae: Araneidae), a new spider species and a novel case of mimicry of an araneopathogenic fungus (Cordycipitaceae: Gibellula).The study describes Taczanowskia waska as the first documented case of a spider imitating a parasitic fungus that infects spiders themselves, a form of mimicry not previously recorded in arachnids. The discovery adds to growing evidence that rainforest ecosystems still hold complex and unexpected evolutionary strategies, many of which remain undocumented.During fieldwork, researchers noted that the animal was so convincing in its disguise that it was first taken for a mushroom, before closer inspection revealed its true identity as a spider.
