• Proposed
  • 2Under Assessment
  • 3Preliminary Assessed
  • 4Assessed
  • 5Published

Nanoscypha tetraspora (Seaver) Denison

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Scientific name
Nanoscypha tetraspora
(Seaver) Denison
Common names
IUCN Specialist Group
Cup-fungi, Truffles and Allies
Assessment status
Proposed by
Rebecca Amesbury
Comments etc.
Rebecca Amesbury

Assessment Notes

Taxonomic notes

Kingdom: Fungi
Phylum: Ascomycota
Subphylum: Pezizomycotina
Class: Pezizomycetes
Order: Pezizales
Family: Sacroscyphaceae
Genus:  Nanoscypha
Species:  Nanoscypha tetraspora
(Kirk et al., 2008)

Why suggested for a Global Red List Assessment?

This species is found in very limited regions and has only been documented a few times. Additionally, it is found in rain forests, which are being deforested, so it is under much greater threat.

Geographic range

This species only has a few documented findings, mostly in Central or South America: Venezuela, Costa Rica, and, primarily, Puerto Rico (Ramirez et al., 2020). It was also found in Madagascar. Nanoscypha tetraspora has been most well-documented in El Yunque National Forest in Puerto Rico, which is a tropical rainforest (USDA, 2020). Given the other geographical regions in which this fungi is found (Costa Rica, Venezuela), it grows the best in rainforest climates (hot and humid) as well as high altitudes .

Population and Trends

Some samples of Nanoscypha tetraspora have been collected from veins of fallen leaves of Cecropia peltata - a plant that is known to have a high fungal infection rate. Even though the specific population of Nanoscypha tetraspora is unknown, this fact suggests that the spread could be similar to that of Cecropia peltata, as an optimistic estimate.
To find the lower bound of the estimate, one can analyze the collected samples. Most of them come from El Yunque National Forest in Puerto Rico, which stretches over 115.07 km2. In total, there have been 7 individuals recorded in El Yunque since the first one in 1912. Since each individual is represented by a separate sporocarp apart from each other by 10m, we can consider all of these specimens as such. The most conservative estimate will assume that almost all individuals in Puerto Rico were collected, and that other regions have similar Nanoscypha tetraspora density. A suitable habitat will be rainforest climates in high altitudes of Costa Rica and Venezuela, representing 12,775km2 and 12,500km2 respectively. Not enough information is known to be able to calculate the EOO and AOO, therefore, the inferred population from known data collectively will be 1516.
This, however, does not account for the unreported subpopulations. Based on plant geographic ranges, including that of Cecropia peltata, the realistic Nanoscypha tetraspora population will be closer to 22,000. The populations are unlikely to be severely fragmented due to continuous habitat and Nanoscypha tetraspora easy spore dispersal. However, large populations are separated by the ocean (e.g. Puerto Rico and Venezuela).
As discussed earlier, due to deforestation, the habitat of this fungus is contracting, and so is the population. Based on current deforestation rates, and accounting for climate change, which makes more areas habitable for this fungus, the estimated population decrease rate is around 0.4% a year. This percentage is likely even higher, given by how Nanoscypha tetraspora was collected and recorded frequently in South America in 1930-1960s, but not over the last couple of decades. However, this change could be due to human factors such as changes in scientific interests.

Population Trend: Decreasing

Habitat and Ecology

This fungus has an orange hymenium, light exterior and blastospores that failed to germinate in experimental conditions, suggesting they function as spermatia (Pfister, 1973). Due to visible physical characteristics, they are easily confused with inoperculate discomycetes (such as Hymenoscyphus) (Denison, 1972). This could lead to overestimation of Nanoscypha tetraspora spread. This species is part of Sarcoscyphacae, distinguished by their occurrence on wood or foliage in early stages to decay. It is saprotrophic.
Overall, there is little documentation as to the habitat and ecology of Nanoscypha tetraspora specifically. However, the order Pezizales, of which Nanoscypha tetraspora is part, can be saprobic, mycorrhizal, or parasitic (on plants). Some samples of Nanoscypha tetraspora have been collected from veins of fallen leaves of Cecropia peltata (also called snakewood, an invasive plant), suggesting a possible mycorrhizal relationship with this species (Kirk, et al., 2008).

Subtropical/Tropical High Altitude ShrublandSubtropical/Tropical High Altitude Grassland


The low amount of documentation on this species shows the threat posed to its existence. Additionally, there have been substantially fewer occurrences of Nanoscypha tetraspora in recent years, with multiple throughout the 1970s, 9 recorded occurrences in 1996, and 0 since then (Ramirez, et al., 2020). This calls into question the existence of the species currently, and any found samples must be preserved and protected. It is likely the current situation regarding the rainforests being destroyed has contributed to the loss of many species within the rainforests, including Nanoscypha tetraspora. Additionally, since it grows on plants and leaves, selective pressures of deforestation might change the mix of plant species which can negatively affect the spread of this fungus. Since this fungus’ hymenium is orange or cadmium yellow (Denison 1972), it is increasingly more easily distinguished in areas where pollution darkens the tree trunks.

Intentional use: large scale (species being assessed is the target) [harvest]

Conservation Actions

According to information from the California Institute of Technology, there are multiple ways to preserve rainforests. First, governments can do their parts by not allowing timber harvesters to “clear cut” large regions of forest as well as making them plant new trees after they harvest. Governments can also create preserved areas where there is no timber harvesting allowed (Hutton). Unfortunately, this large task is mainly in the hands of the government and large companies that are cutting down the forests, but citizens can do their part through advocacy and outreach.

Research needed

More population sampling to determine the prevalence of this fungus.
Determining which plant species this fungus interacts with, to better determine its spread.
Testing in the lab to determine the best climate under which it grows in order to narrow the search. This would also have implications for how climate change is affecting its growth.

Use and Trade

There are no documented uses of Nanoscypha tetraspora commercially


Country occurrence

Regional Population and Trends

Country Trend Redlisted