species produce rhizomorphs as exploratory structures to find new substrates for the fungus. Although it is not currently known if they are pathogenic, our studies suggest they may be similar to some Armillaria species acting as opportunistic pathogens on compromised and unhealthy trees. However, they differ from Armillaria in their aboveground growth and tendency to grow upward toward light. In Yasuni National Park, the various species produce rhizomorphs with different morphological characteristics in terms of their surface texture, branching characteristics, and growth patterns. Little is known about these fungi, and our studies showed they are genetically different from known species. We recently described four new species and a new variety from our research site: Atroporus yasuniensis, Atroporus tagaeri, Neodictyopus sylvaticus, Polyporus taromenane and Polyporus leprieurii var. yasuniensis (https://doi. org/10.1371/journal.pone.0254567). Te most common species is Polyporus leprieurii var. yasuniensis which is found in different habitats from temporary flooded valleys to high forested ridges allowing the fungus to prevail for long periods of time in a competitive ecosystem where hundreds of species are fighting for a niche to grow in. Other aerial rhizomorph producing


Unlike temperate areas of the world, the tropical Amazon rainforest has fungi that produce rhizomorphs that grow aboveground. These move along logs (top left photo) and over forest vegetation from tree to tree producing large numbers of aerial rhizomorphs (top right photo, with author Cristina Toapanta holding a large mass of rhizomorphs). We recently described several new species of Polyporaceae producing these rhizomorphs (bottom photo).


expect the Amazon forest to be filled with massive networks of rhizomorphs above ground. To our amazement, we saw black and reddish brown fungal rhizomorphs on logs, tree trunks, branches, and small plants extending in every direction, including up, in the wet forest. One area we studied was the rainforest in Yasuni National Park in Ecuador. Tese investigations were done with Ecuadorian collaborators Maria Ordoñez, Charles Barnes, and


30 FUNGI Volume 15:1 Winter 2022


the Pontificia Universidad Católica del Ecuador. Te park is well known for being one of the most biodiverse places on earth. As an example, there are more tree species in one hectare than are native to the United States and Canada combined. With this type of diversity, you can only speculate how many fungi may be found in the forest. One major group of fungi are


the Polyporus-like species with aboveground rhizomorphs. Tese


fungi in subtropical and tropical forests are Marasmius and Gymnopus, often referred to as the Horsehair fungi. Tese species produce rhizomorphs that are thin thread-like structures. With rhizomorphs abundant above ground, some bird species selectively use them for nests in the Brazilian Amazon and the Yanomami Indigenous People collect rhizomorphs to incorporate into baskets they weave. Tis provides a black fiber for making interesting patterns to decorate their baskets. Professor Noemia Kazue Ishikawa, one of Brazil’s leading ethnomycologists from the Instituto Nacional de Pesquisas da Amazônia in Manaus, has documented the use of rhizomorphs for decorative work in basketry in a new book, Përs: the Fungus that Yanomami Women Use in Teir Basketry (a pdf is available from the authors). Rhizomorphs are versatile structures


that provide advantages to the species producing them. Tese vegetative


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