Researchers from the Chinese Academy of Sciences discovered two new species of parasitic fungi preserved in amber dating back approximately 99 million years. The fossilized entomopathogenic fungi provide some of the oldest direct evidence of parasitic relationships between fungi and insects, offering insights into the co-evolution of these organisms, according to Phys.org.
The two previously unknown species, identified in amber specimens at the Natural History Museum in England, have been named Paleoophiocordyceps gerontoformicae and Paleoophiocordyceps ironomyiae. Paleoophiocordyceps gerontoformicae is characterized by fine fungal stalks emerging from an ant pupa, while Paleoophiocordyceps ironomyiae is noted for its phallus-like fruiting body protruding from a fly's head.
"This discovery provides important evidence for exploring the co-evolution of fungi and insects," said Wang Bo, a researcher at the Nanjing Institute of Geology and Palaeontology under the Chinese Academy of Sciences, according to News China. Wang explained that very few fossil evidence of Ophiocordyceps fungi was found because fungi have soft structures and decompose easily, which limits understanding of their origin and evolution.
"The fossil evidence shows that the infectious fungi were already adapted to two different insect hosts a hundred million years ago, an ant and a true fly," said paleoentomologist Edmund Jarzembowski, indicating early host shifts that shaped the evolution of Ophiocordyceps fungi, as reported by Phys.org.
The new species share distinctive traits with extant Ophiocordyceps species, which are known for their ability to infect insects, taking over their nervous systems and forcing them to climb to high places before killing them to release spores. This suggests that parasitic fungi were infecting insects and possibly controlling their behavior in ancient times, and may be ancestors of modern 'zombie ant fungi'.
Using high-resolution analytical methods, such as micro-CT scanning, researchers discovered the hosts that the newly discovered fungi parasitized, offering a glimpse into past epochs and the interactions between organisms. The research team collected and analyzed genetic data from 120 extant Ophiocordyceps species, revealing that the genus Paleoophiocordyceps may have diverged from Ophiocordyceps about 130 million years ago, earlier than previous estimates of around 100 million years.
The study suggests that during the Cretaceous period, Ophiocordyceps underwent host shifts to Lepidoptera and Hymenoptera, coinciding with the diversification of moths and ants. This offered new ecological opportunities for fungal specialization. The research pushes back the origin of the genus Ophiocordyceps by about 30 million years compared to previous estimates, suggesting that fungi increased their evolutionary success over time by transitioning to new hosts.
"The fossils not only document some of the oldest evidence of insect-pathogenic fungi but also support the view that Ophiocordyceps diversified in tandem with its insect hosts," the authors concluded, according to Phys.org.
Amber, formed by the hardening of tree resin over millions of years, is renowned for preserving moments of natural history, including detailed inter-organism relationships revealed by the discovery of ancient fungal fossils. These two specimens are among the oldest evidence of 'zombie' fungi, positioned just after a Lower Cretaceous species identified in 2008.
The results of the study have been published in Proceedings of the Royal Society B.
The preparation of this article relied on a news-analysis system.