Cinereomyces dilutabilis (Loguercio-Leite & J. E. Wright) Miettinen, 2012 (≡ Diplomitoporus dilutabilis, Log.-Leite & J.E.Wright, 1998).
Cinereomyces dilutabilis is a rare wood-decaying resupinate polypore. It occurs in the Atlantic Forest of Southern Brazil and in Tropical Dry Forest of Costa Rica, both threatened vegetational domains.
The species is assessed as Near Threatened (NT) under criterion A3c + C1.
Cinereomyces dilutabilis is only known from six sites, most of them in Brazil, except for one in Costa Rica. The brazilian specimens were collected in the Atlantic Forest domain of Southern and Southeastern Brazil, in the states of São Paulo (2 collections), Santa Catarina (5 collections) and Rio Grande do Sul (5 collections). It is expected that the species occurs throughout the Atlantic Forest fragments of Brazil. There are olnly two collections from Costa Rica, Guanacaste province, from the Tropical Dry Forest domain. It is also expected that the species occurs in other similar areas in Central America.
Currently, C. dilutabilis is known from only 6 sites and 13 collections. Most of records are from the Atlantic Forest of Brazil, in São Paulo, Santa Catarina and Rio Grande do Sul states. It is expected that the species occurs throughout the Atlantic Forest of Brazil, which is now mainly composed by fragments and secondary forests, with only 28% of its original area remaining (Tabarelli et al. 2010, Rezende et al. 2018). Also, there are only two collections from Costa Rica, Guanacaste province, in the Tropical Dry Forest domain. This forests extends from Costa Rica to Chiapas region in Mexico,so, it is expected to be found in other Central American areas with similar habitat. The Tropical Dry Forest domain has suffered a massive loss of area, remaining with less than 2% of its original area intact in the Pacific side (Janzen 1988). Specifically, in Costa Rica, only 24% of the original forest cover is left (Portillo-Quintero and Sánchez-Azofeifa 2010). The collections of Costa Rica and Southern Brazil are 5600 kilometers apart, characterizing two known subpopulations for the species.
In areas where the Funga has been intensively surveyed, such as parts of the Atlantic Forest domain in Brazil, the species was scarcely found, which indicates that the species is likely rare. There are a total of 2000 estimated sites, with 5-10 mature individuals each. Total population is estimated at 15.000 to 20.000 mature individuals. It is possible that these numbers are overestimated, as the species may not find conditions to occur in much of its potential range, given the poor current state of the forests where it could possibly be found.
With the two subpopulations occuring in threatened domains (Myers 2000), the largest subpopulation occurring in the Atlantic Forest domain, that has just 28% of its original area remaining, mostly composed by secondary forests (Tabarelli et al. 2010, Rezende et al. 2018), and an ongoing decline predicted to continue in the near future, the species has a projected decline in population size of at least 10% over the next 20 years, covering three generations of the species.
Population Trend: Decreasing
Cinereomyces dilutabilis is a wood-decaying fungus currently found in Brazil, in the Atlantic Forest domain and in Costa Rica, in the Tropical Dry Forest domain. The species is expected to be widespread throughout these domains.
Cinereomyces dilutabilis is found in the Atlantic Forest of Brazil, regarded as a biodiversity hotspot for conservation priorities due to its high diversity, endemism rates and habitat loss (Myers et al. 2000). This phytogeographical domain is estimated to have only 28% of its vegetation remaining, with the remnants being fragmented and composed mostly by secondary forests (Tabarelli et al. 2010, Rezende et al. 2018). According to Pinto et al. (2006), the Atlantic Forest is found in this situation due to predatory exploration of the resources and human actions, like territorial occupation. About 60% of the Brazilian population lives in the Atlantic Forest, mainly in coastal areas, where the country’s largest cities are located (Rezende et al. 2018). Other threats to the Atlantic Forest include increase in fire frequency and intensity, introduction of exotic and invasive species and the connection between these factors (Brooks & Balmford 1996, Tabarelli et al. 2006, Pinto et al. 2006). Also, reduction and ‘savannization’ of Atlantic Forest is expected due to climate change in the next decades (Salazar et al. 2007). The Tropical Dry Forest domain in Central America is even more endangered, remaining with only 2% of its original area intact in the Pacific side (Janzen 1988). According to Portillo-Quintero et al. (2010), the Tropical Dry Forest area in North and Central America was 719,338 km², with only 203,884 km² remaining today, from which just 624 km² (0,3%) are under protection, having undergone a loss of 72% of the potential extent. Specifically, in Costa Rica only 24% of original area remains (Portillo-Quintero & Sánchez-Azofeifa 2010). Most of the Tropical Dry Forest domain is severely fragmented, and the threats are multiple and complex, where it comprises the economy, policies, land owners, historical losses, and other factors within Central American countries (Janzen 1988).
The main actions to prevent the decline of the species are the protection of its habitat by the implementation of Protected Areas and enforcement of public policies to recover secondary forests.
More surveys are needed to better understand the species ecology. Also, further analyses are needed to confirm the conspeficity of the brazilian and central-american subpopulations. Currently, there are no available DNA sequences of this species, and its phylogenetic and taxonomic status need to be better studied.
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