Costa Rica Has Thousands of Fungi We Still Don’t Know About: UCR Study Reveals How Much Remains Discovered

There is a hidden world that wakes up after the rain. It thrives across decaying tree trunks, carpets the forest floor, hides under leaf litter, and lives inside other organisms. It exists everywhere in the rainforest, yet much of it remains unnamed.

That world belongs to fungi.

A study conducted by researchers at the University of Costa Rica (UCR) reconstructed over a century of mycological history. By analyzing 78,333 collection records gathered across 170 years (1854–2023), scientists revealed a compelling paradox: while Costa Rica is a global leader in cataloging tropical biodiversity, it has barely scraped the surface of its fungal kingdom.

Expanding the Catalog: From 5,676 to 6,789 Known Species

The study—published in the journal Plants, People, Planet—drew 99.8% of its data directly from fungaria (scientific collections of preserved fungal specimens) and culture collections.

When researchers combined these physical collections with existing scientific literature, the tally of documented fungi species in Costa Rica jumped from 5,676 to 6,789—a 19.6% increase in known species richness.

Key Takeaway: The figure of 6,789 species represents only what has been formally documented. Statistical estimation models suggest the real number of fungal species living in Costa Rica could range anywhere from 6,900 to over 40,000 species.

        CR Fungal Knowledge Gap (By Numbers)
        
  [ Recorded Species ] ███ 6,789
  [ Estimated Range  ] ██████████████████████ 40,373

The Mystery of Unnamed Specimens

Why is the gap between known and estimated species so wide?

1. Unidentified Species: Of the 78,333 records analyzed, 62,582 specimens (79.9%) were identified only to the genus level. Scientists knew the general family group, but could not pin down the exact species.
2. Disconnected Archives: The team discovered 3,927 species described in academic literature that were completely missing from physical fungaria collections, showing that historical knowledge is fragmented between books and museum shelves.

Where Do Fungi Thrive in Costa Rica?

The research mapped key geographical hotspots where fungal diversity reaches its peak:

• Lower Montane Moist Forests: Mid-elevation regions such as Zarcero, Ochomogo, and the highlands of Alajuela and Cartago.
• Tropical Moist Forests: Lowland ecosystems, including Carara National Park and Pacific coastal forests.
• Premontane Wet Forests: High-humidity zones across the Talamanca, Central Volcanic, and Tilarán mountain ranges.

Fungal fruiting bodies (the structures we recognize as mushrooms) hit their peak during the rainy season. However, different fungal families adapt differently:

• Agaricales & Boletales (classic capped mushrooms and boletes) respond dramatically to rain surges, blooming almost overnight.
• Polyporales (bracket and shelf fungi on wood) remain much more stable, clinging to dead trees straight through the dry season.

A 170-Year Timeline of Costa Rican Science

The study also documents the history of scientific conservation in Central America. Collection rates varied wildly across eras:

• 1854–1920: ~37 specimens collected per year (early European and natural history expeditions).
• 1921–1962: ~78 specimens per year.
• 1963–1989: ~199 specimens per year as local UCR researchers took the lead.
• 1990–2015 (The INBio Golden Era): ~2,500 specimens per year, driven by systematic biodiversity inventories under the former National Institute of Biodiversity (INBio).
• 2016–Present: Collection rates dropped back to ~283 specimens per year.

       Historical Specimen Collection Rates (Per Year)
       
  1854-1920 | █ 37
  1921-1962 | ██ 78
  1963-1989 | █████ 199
  1990-2015 | ████████████████████████████████ 2,500  <-- INBio Era
  2016-2023 | ██████ 283

Why Fungi Matter for Conservation and Climate Change

When people discuss Costa Rican biodiversity, attention naturally goes to sloths, toucans, jaguars, and orchids. Fungi are frequently left out of the conservation narrative, despite being essential nutrient recyclers and soil building blocks.

“Fungaria aren’t just dusty collections—they are baseline ecological maps. A preserved mushroom from 50 years ago tells us what climate, plants, and soil conditions existed in that exact spot.”

As climate change alters temperature and rainfall patterns across Central America, understanding how fungi adapt will be vital for forest restoration, agricultural health, and conservation policy.

What’s Next for Costa Rican Mycology?

To fully unlock this hidden world, researchers emphasize three priorities:

1. Sustained Funding: Rebuilding systematic collection programs similar to the INBio model.
2. Taxonomic Training: Educating the next generation of tropical mycologists to identify the 80% of unclassified specimens.
3. Community Ecotourism: Integrating fungal discovery trails into rural ecotourism and community science projects.