This species was originally described as Stereum sclerotioides by Lloyd (1922), based on a specimen with no precise data, from the Amazon Forest. In 1959, D.A. Reid placed this species in the genus Cymatoderma Reid  (1959).
This is a very rare species, having being recorded from only 6 sites since 1922, represented by no more than 25 collections. The species has conspicuous large, colorful basidiomata, thus the reduced number of collections is probably due to its rarity. Although Amazon Forest domain is the largest and most preserved Tropical Forest in Brazil, the areas where the species occurs are also under threat, with the Amazon facing growing deforestation and the possibility of approaching its tipping point (Amigo 2020, INPE 2020).
The species is assessed as Near Threatened under criterion A3c + C1.
Currently known from the Amazon Forest of Brazil (Mato Grosso and Roraima states), Peru (Loreto Department) and Colombia (Caqueta and Amazonas). It is also known from northern Panama and southern Costa Rica, both in Montane Tropical Forests near Volcán Barú/Cordillera Talamanca.
In the Amazon, the known sites are about 1.500 - 2.000 km away from each other. The species is expected to occur throughout the Amazon and through tropical forests of Colombia into Panama and Costa Rica.
The species was first recorded in 1922 in the Brazilian Amazon Forest without precise information about its locality. Six other records are known from the Amazon, four in the forest’s western part, in Iquito, Peru (1984) and two localities in Colombia, one in the northern part, in Roraima, Brazil (2008), and one in the southern part, in Mato Grosso, Brazil (2018). The species has also been recorded in Central America, in Costa Rica and Panama, where ca. 20 collections were made, all in the tropical montane forests in the Cordillera Talamanca.
Although this species has a widespread distribution, it is likely rare, as there are few records even in well sampled areas. For example, at the Cristalino Particular Reserve, in Mato Grosso state, the Funga has been studied and documented intensively in the last decade, but just one basidiome of C. sclerotioides was found.
Based on the potential occurrence area, it is conservatively estimated that there are up to 2000 sites, each holding 5-10 mature individuals, resulting in a total population size of up to 20.000. However, due to the species rarity, these numbers could be overestimated, and population may not exceed 10.000 mature individuals.
The Amazon Forest is undergoing rapid deforestation and facing increased fire frequency and intensity, following years of decline (INPE, 2020). The forest could be dangerously approaching a tipping point, when the forest can no longer sustain its own water cycles, drastically changing into a savannah, leading to huge biodiversity losses (Amigo 2020).
Central American montane forests are under threat throughout much of their range due to land use changes, including timber harvest, conversion to pine and other non-native tree plantations, agriculture, and expansion of towns and cities. Further pressure and population reductions are expected to continue. Deforestation in Colombia has increased in recent years and is anticipated to continue into the near future. Parts of the Talamancas are protected in National parks, but other areas are privately held, and there is limited logging ongoing as well as commercial and housing developments. For the mountain areas were this species occurs, the total forest cover has not significantly changed in the last 20 years (MINAE 2018).
The species is estimated to have a population decline of 10-20% in the next 20 years.
Population Trend: Decreasing
This species likely occurs throughout the Amazon Forest domain to the Montane Tropical Forests of Central America, growing on buried pieces of heartwood.
The Amazon ecosystem has been facing a rapid growth in deforestation and fire rates, after years of decline (INPE 2020), and the forest could be dangerously approaching a tipping point, when the forest can no longer sustain its own water cycles, drastically changing into a savannah, leading to huge biodiversity losses (Amigo 2020). The Amazon domain in Brazil suffers from a predative logging and deforestation for cattle and implementation of soybean plantations, that are results of the economy plan for Brazilian Amazonia (Fernside 2008). Even in the Western Amazon (includes parts of Bolivia, western Brazil, Colombia, Ecuador and Peru), that is relatively more preserved than the Eastern Amazon (mostly inside Brazilian territory), there are threats like ilegal mining, oil and gas blocks, that tend to increase over time (Finer et al. 2008). The area where the species occurs has declined at least 18% in the last 30 years.
Central American montane forests are under threats throughout much of their range due to land use changes, including timber harvest, conversion to pine and other non-native tree plantations, agriculture, and expansion of towns and cities.
The main action to prevent the decline of the species is preservation of the known and eventual new discovered sites by implementing conservation areas.
More surveys and long term studies are needed to identify other sites and to better estimate the population size. Also, studies on the habitat of the species and its ecological relationships are needed. Currently, there are no available DNA sequences of this species, and its phylogenetic and taxonomic status need to be confirmed.
Amigo, I. (2020). When will the Amazon hit a tipping point? Nature 578, 505-507. doi: 10.1038/d41586-020-00508-4
Fearnside, P. M. (2008). Amazon Forest maintenance as a source of environmental services. Anais Da Academia Brasileira de Ciências, 80(1), 101–114. https://doi.org/10.1590/s0001-37652008000100006
Finer, M., Jenkins, C. N., Pimm, S. L., Keane, B., & Ross, C. (2008). Oil and Gas Projects in the Western Amazon: Threats to Wilderness, Biodiversity, and Indigenous Peoples. PLoS ONE, 3(8), e2932. doi:10.1371/journal.pone.0002932
INPE - National Institute for Space Research. Earth Observation General Coordination. Monitoring Program of the Amazon and Other Biomes. Deforestation – Legal Amazon – Available at http://terrabrasilis.dpi.inpe.br/downloads/. Accessed on 20 March 2020.
Lloyd, C.G. (1922). Mycological Writtings, vol. 7, letter 66 nº 1, Cincinnati, Ohio. pp. 1106–1136.
MINAE – SINAC – CONAGEBIO – FONAFIFO (2018). Resumen del Sexto Informe Nacional de Costa Rica ante el Convenio de Diversidad Biológica. . Programa de Naciones Unidas para el Desarrollo - Apoyo técnico para que las Partes Elegibles desarrollen el Sexto Informe Nacional para el CDB (6NR-LAC) Costa Rica.
Reid, D.A. (1958). The Genus Cymatoderma Jungh. (Cladoderris). Kew Bulletin 13(3): 518–530.
Rivers, M.C., Bachman, S.P., Meagher, T.R., Lughanda, E.N., Brummitt, N.A. (2010) Subpopulations, locations and fragmentation: applying IUCN red list criteria to herbarium specimen data. Biodiversity and Conservation, 19(7), 2071–2085. doi:10.1007/s10531-010-9826-9
Welden, A.L. (1960). The genus Cymatoderma (Thelephoraceae) in the Americas. Mycologia, 52(6), 856-876.