Gibellula agroflorestalis

Imagine an infectious disease that turns you into an immobile white statue - while that sounds like something out of a dystopian science fiction story, this is the fate which awaits any spiders that encounter Gibellula, a genus of araneopathogenic (spider-killing) fungi. There are many species of this fungi found all over the world and their spores can infect all kinds of spiders. Gibellula is in the same broad group of fungi as the zombie ant fungi, but instead of producing a single or a few mushroom-like fruiting bodies that emerge from the carcass of their hosts, Gibellula smothers the infected spiders in a dense layer of white, fluffy mould.

Left: Examples of spiders infected with Gibellula agroflorestalis including orb-weavers (a-c) and jumping spider (d), Centre: numerous spore-bearing stalks (conidiophores), their mycelia twisted together, Right: Close-up of the head of a conidiophore.
Photos from Fig 3 and 4 of the paper

This post focuses on Gibellula agroflorestalis, a newly described fungus which was discovered by a group of researchers in the agroforestry systems located at the Abreu e Lima municipality of Brazil. 

Agroforestry is a system of agriculture where instead of cultivating a single type of crop, different crop plants are grown alongside trees and other plants, and these environments can provide habitats for a wider range of organisms. The forests that the researchers studied were composed of fruit plants such bananas, coconuts, limes, and mangoes, growing alongside various trees such as pink trumpet trees, pau brasil, and juazeiro.

So how does one find mouldy spiders amidst this semi-cultivated forest? Well, in short, with a lot of time and effort. The researchers hiked through multiple agroforestry properties while meticulously examining every plant they came across, carefully inspecting the underside of their leaves which is where many fungus-infected spiders end up. On the rare occasion when they come across an infected spider, it was collected intact along with the leaf it was sitting on, placed into a plastic cup, and later stored in silica gel to preserve the specimen. In total, the researchers found 17 infected spiders, ranging from jumping spiders to crab spiders to orb-weavers, alongside other spider hosts which could not be identified, because by that stage they have become more Gibellula than spider, twisted and fungal.

When the researchers examined the fungus under a microscope, they found that the structure and size of its teardrop-shaped spores were different from other known species of Gibellula. Furthermore, DNA analyses showed the fungus to be genetically distinct, and that as a species, G. agroflorestalis is fairly genetically diverse, which is probably why it is able to infect so many different types of spiders.

While there are other species of Gibellula fungi out there which have been recorded from spiders in natural forests, G. agroflorestalis was the first to be recorded in an agroforestry system, showing that these environment may in fact serve as habitats to some unique species. The discovery of G. agroflorestalis reminds us that a lot of unseen biodiversity can be found through careful observations. So it's good to stop and smell the roses, but you should also check underneath the leaves for mouldy spiders.

Reference:

da Rocha Alves, J.E., da Silva Santos, A.C., Pedroso, S.K.B., Melo, R.F.R., & Tiago, P.V. (2025). Untangling a web of spider fungi: Gibellula agroflorestalis (Hypocreales, Ascomycota), a new species of spider parasite from Brazil. Journal of Invertebrate Pathology 209:108278.