A team of researchers from the University of Tennessee, Knoxville, has discovered a new genus of fungi that grows on grasses in various regions of the world. The new genus, named Metacampanella, belongs to the family Marasmiaceae and includes several species that were previously assigned to other genera, such as Campanella and Tetrapyrgos.
Metacampanella subdendrophora: The first species of the new genus
The first species of Metacampanella to be described was Metacampanella subdendrophora, which was originally named Campanella subdendrophora by Rolf Singer in 1962 and later transferred to Tetrapyrgos by Machiel Noordeloos in 2011. This species produces small, brownish mushrooms with bell-shaped caps and slender stems on grasses in the US Pacific Northwest. The researchers examined the DNA sequences of this species and compared them with those of other members of the Marasmiaceae family. They found that Metacampanella subdendrophora was not closely related to either Campanella or Tetrapyrgos, but formed a distinct lineage within the family. Therefore, they proposed a new genus name for this species and its allies.
Metacampanella dendrophora: A new species from Costa Rica
Another species of Metacampanella was discovered in Costa Rica by Karen Hughes and Ronald Petersen in 2017. They collected specimens of a mushroom that grew on dead grass stems in a cloud forest. The mushroom had a similar appearance to Metacampanella subdendrophora, but differed in some microscopic features, such as the presence of cystidia (specialized cells) on the gills. The DNA analysis confirmed that this species was closely related to Metacampanella subdendrophora, but distinct enough to warrant a new name. The researchers named it Metacampanella dendrophora, meaning “tree-loving”, because it grew on grasses that were attached to trees.
Metacampanella sp.: A new species from New Zealand
A third species of Metacampanella was found in New Zealand by Peter Johnston and Jerry Cooper in 2018. They collected specimens of a mushroom that grew on grasses in a pasture. The mushroom had a whitish cap with brownish scales and a dark brown stem. The DNA analysis showed that this species was also closely related to Metacampanella subdendrophora and Metacampanella dendrophora, but differed in some morphological and molecular characters. The researchers did not name this species yet, because they wanted to collect more material and study its variability.
Metacampanella sinecystidia: A new endophytic species from Oregon
An endophyte is an organism that lives inside a plant without causing any apparent harm or benefit to the host. Some fungi are known to be endophytes of grasses, such as Epichloë and Neotyphodium, which produce alkaloids that protect the plants from herbivores. In 2019, Hughes and Petersen isolated a fungal strain from the roots of Elymus mollis, a dune grass native to Oregon. They identified it as belonging to Metacampanella based on its DNA sequence. They also observed its morphology under the microscope and found that it lacked cystidia on the gills, unlike the other species of the genus. They named it Metacampanella sinecystidia, meaning “without cystidia”.
Metacampanella sp.: A possible endophytic species from Kansas
Another possible member of Metacampanella was detected in Kansas by Jorge Herrera and colleagues in 2011. They analyzed the DNA sequences of fungi that were isolated from prairie dog dung. Prairie dogs are rodents that feed on grasses and other plants. The researchers found that some of the fungal sequences belonged to an unknown taxon that was closely related to Metacampanella subdendrophora. They speculated that this taxon might be an endophyte of grasses that was ingested by prairie dogs and passed through their digestive system.
The ecological significance and diversity of Metacampanella
The discovery of a new genus of fungi on grasses is important for understanding the diversity and evolution of the fungal kingdom. Grasses are one of the most widespread and dominant plant groups on Earth, and they host a variety of fungi that interact with them in different ways. Some fungi are pathogens that cause diseases, such as rusts and smuts. Some fungi are mutualists that enhance the growth and survival of grasses, such as mycorrhizae and endophytes. Some fungi are saprotrophs that decompose dead plant material, such as Metacampanella and other mushrooms.
Metacampanella is a new addition to the saprotrophic fungi that grow on grasses. It is not yet clear how widespread and diverse this genus is, or what role it plays in the ecosystem. The researchers suggest that more environmental studies are needed to identify other members of this genus and to explore their distribution, ecology and phylogeny.
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