The Zombie Spider of Northern Ireland: A Creation of Gibellula attenboroughii

On the ceiling of an old gunpowder store in Northern Ireland, researchers discovered the body of a dead spider enveloped by a rare fungus. The fungus had spread across the entire body, forming delicate white filamentous growth that appeared both intricate and strangely eerie. Through morphological study and molecular analysis, scientists determined that the organism represented a previously unknown species. It was named Gibellula attenboroughii, in honor of the renowned natural history broadcaster Sir David Attenborough, acknowledging his lifelong efforts to bring the wonders of nature to the public. The discovery provides an opportunity to better understand the remarkable ecological relationship between spiders and the parasitic fungi that can effectively transform them into “zombie” hosts.

The genus Gibellula, belonging to the family Cordycipitaceae, consists of fungi that specialize in infecting spiders. These fungi invade the host, eventually killing it, and then produce elaborate spore-bearing structures on the spider's body to disperse new spores. Most species of Gibellula have historically been recorded in tropical or subtropical environments, particularly in humid forests of South America and Southeast Asia. For this reason, the discovery of such a fungus in the temperate climate of the British Isles attracted considerable attention.

The holotype of Gibellula attenboroughii (IMI 507230). A, B: Dried specimen of Metellina merianae, showing multiple synnemata emerging from the spider's body and distributed across its surface; C, D: Microscopic structure of the synnemata showing the conidiophores; E, F: White spore columns（Image source：Evans HC et al. (2025)， CC BY-NC-ND 4.0 ）

The new species was first noticed during filming for the BBC series Winterwatch and Springwatch. The television crew had been recording footage inside an abandoned gunpowder store at Castle Espie Wetland Centre in Northern Ireland when they encountered a cave-dwelling orb-weaving spider, Metellina merianae. The spider appeared to have abandoned its web shortly before death and had crawled toward an exposed position high on the ceiling, stopping in the center of the structure. This behavior closely resembles the well-known “zombie ant” phenomenon caused by fungi in the genus Ophiocordyceps. In such cases, infected hosts undergo behavioral changes that lead them to positions favorable for fungal spore dispersal.

The spore-bearing structures of Gibellula attenboroughii, known as synnemata, appear as elongated clusters that branch into multiple slender projections, creating a distinctive flower-like form. This morphology may represent an adaptation that enhances the efficiency of spore dispersal. When grown in laboratory culture, the fungus develops slowly. Visible colonies require several months to form, yet the structures produced in culture closely resemble those seen in nature.

The fungus primarily infects two spider species: Metellina merianae and the European cave spider Meta menardi. Both species typically inhabit dark and humid environments such as caves, tunnels, and other sheltered subterranean structures. Infected individuals are frequently discovered dead on cave ceilings or exposed walls rather than within their original webs. Researchers suspect that the fungus interferes with the spider's nervous or muscular control, causing it to leave its concealed habitat. Once the spider dies, the fungus rapidly spreads across the exoskeleton, producing white filamentous structures that emerge from the body. Over time the entire spider effectively becomes a spore-producing structure, releasing dry spores that are carried by air currents through the cave system in search of new hosts.

Interestingly, the appearance of the fungus differs depending on the spider species it infects. On Metellina merianae, the fungus produces complex and densely packed spore heads resembling those of Aspergillus. On Meta menardi, however, the structures are simpler and resemble those of Penicillium. These differences may reflect variations in the microclimates of the spiders' habitats. Metellina merianae is often found closer to cave entrances where conditions are somewhat drier, whereas Meta menardi tends to occupy deeper, darker, and more humid sections of caves. The fungus may adjust its spore-producing structures in response to these environmental differences to maximize dispersal success.

Gibellula attenboroughii infecting Metellina merianae（Image source：Evans HC et al. (2025)， CC BY-NC-ND 4.0 ）

Gibellula attenboroughii infecting Meta menardi（Image source：Evans HC et al. (2025)， CC BY-NC-ND 4.0 ）

Beyond its manipulation of spider hosts, Gibellula attenboroughii may itself become the host of other fungi. Some specimens display sticky fungal masses growing on their surfaces. When these were isolated and cultured, they were identified as fungi related to genera such as Nodulisporium and Lecanicillium. These “fungi within fungi” illustrate the layered complexity of microbial ecosystems, demonstrating that even within seemingly isolated cave environments, intricate parasitic relationships can exist.

Historical records indicate that fungi of the genus Gibellula have been present in Britain for far longer than previously recognized. As early as 1892, the British mycologist Mordecai Cubitt Cooke described a spider-infecting fungus named Isaria arachnophila, though detailed locality and specimen information were lacking. Later, in the mid-twentieth century, Thomas Petch conducted more systematic studies in the wetlands of eastern England and documented the species now known as Gibellula arachnophila. During the 1940s and 1950s, E.A. Ellis collected more than ninety specimens in Norfolk over a decade of fieldwork, demonstrating that these fungi were relatively common in local wetland habitats. Many of these historical specimens are preserved today in the fungal collections of Kew Gardens and have provided valuable material for modern reassessment.

By comparing historical specimens with newly collected material, researchers have revealed that the diversity of Gibellula in the British Isles is far greater than previously recognized. In addition to the newly described species, molecular evidence has led to the reassignment of two spider-parasitic fungi formerly placed in the genus Torrubiella into the genus Gibellula. These are now recognized as Gibellula albolanata and Gibellula aranicida.

The discovery of Gibellula attenboroughii does more than add another species to the fungal catalog. It also opens a new avenue for studying the phenomenon of “zombie spiders” in temperate regions. To ensure the successful dispersal of their spores, these fungi have evolved the ability to alter the behavior of their hosts, guiding them to locations where fungal reproduction is most effective. Such interactions represent a striking example of ecological complexity and provide intriguing insights for research in neurobiology, parasitology, and behavioral ecology.

Habitat of Gibellula attenboroughii. A, B: Whitefathers' Caves above the River Barran in County Cavan; C: An infected spider on the cave ceiling at an early stage of infection; D: The specimen after drying（Image source：Evans HC et al. (2025)， CC BY-NC-ND 4.0 ）

Author: Shui-Ye You

Reference:

Evans HC et al. (2025). The araneopathogenic genus Gibellula (Cordycipitaceae: Hypocreales) in the British Isles, including a new zombie species on orb-weaving cave spiders (Metainae: Tetragnathidae). Fungal Syst Evol.

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