Assessment Notes

Justification

Tylopilus obscurus is a large and distinctive pored mushroom known from forests with Quercus in Colombia and Costa Rica. In Colombia the species forms ectomycorrhizas with Quercus humboldtii. In Costa Rica, T. obscurus is only known from a few scattered sites in the Cordillera Talamancas where it has been found associated with Quercus copeyensi and Q. seemannii (Halling and Mueller 2005). It is not known if the species occurs with Quercus in northern Panama.  As Tylopilus obscurus is ectomycorrhizal and requires a Quercus host, a decline in host population directly negatively impacts its population size. Given that the sites in Costa Rica are relatively stable while the sites in Colombia will continue to face significant threats and continued decline, the estimated past and future decline for the population of Tylopilus obscurus is projected to be between 20-25% over three generations. Therefore, it is listed as Near Threatened.

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Geographic range

Tylopilus obscurus is an ectomycorrhizal fungus associated with Quercus species in Costa Rica and Colombia. This species was first described from Colombia in wet montane forests, but it has been reported also from Costa Rica. In Colombia this species has been collected in Antioquia, Tolima and Santander departments (Vasco-Palacios and Franco 2013, Vargas and Restrepo 2019). In Costa Rica it appears to associate with Q. copeyensis and possibly with Q. seemannii in the Cordillera Talamanca. The species is known from diverse sites in this Cordillera. It is possible that the species occurs with Quercus in northern Panama, but there are no reports.

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Population and Trends

Tylopilus obscurus is known from forests with Quercus in Colombia and Costa Rica. In Colombia the species forms ectomycorrhizas with Quercus humboldtii in the Antioquia, Tolima and Santander departments. There are 15 herbarium specimens collected from 12 different localities in Antioquia and Tolima. Those collections  are housed in the herbarium at the University of Antioquia (HUA). Recently, this species was also reported from Santander (Vargas and Restrepo 2019). Its host tree has a wider distribution in Colombia, and T. obscurus likely occurs in other localities around the country. In Costa Rica, T. obscurus is only known from a few scattered sites in the Cordillera Talamancas where it has been found associated with Quercus copeyensi and Q. seemannii (Halling and Mueller 2005). It is not known if the species occurs with Quercus in northern Panama.


There is no direct information that the population has declined, but a significant decline is inferred due to extensive past and ongoing habitat loss and decline in habitat quality. Further pressure and population reductions are expected to continue. There has been a nearly 42% loss of Quercus humboldtii populations in Colombia, and the tree has been nationally listed as Vulnerable (VU A2cd) there (Cardenas and Salinas 2007). Deforestation in Colombia has increased in recent years and is anticipated to continue into the future. A loss of its mycorrhizal host directly impacts T. obscurus - and it is estimated that the species has undergone rapid population decline in the past and that will continue into the future resulting in a population decline of between 30-50% in Colombia, the primary country that it inhabits. There is less data available to predict the decline of the species in Costa Rica. 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 et al. 2018). As Tylopilus obscurus is ectomycorrhizal and requires a Quercus host, a decline in host population directly negatively impacts its population size. As the sites in Costa Rica are relatively stable while the sites in Colombia will continue to face significant threats and continued decline, the estimated past and future decline for the population of Tylopilus obscurus is considered to be between 20-25% over three generations.

Population Trend: decreasing

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Habitat and Ecology

Tylopilus obscurus is restricted to wet montane forests with Quercus humboldtii in Colombia, and with Q. copeyensi and Q. seemannii in Costa Rica. The species is obligatorily ectomycorrhizal with Quercus species. It has been commonly encountered at the sites where it has been reported.

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Threats

The main known threat to Tylopilus obscurus is from habitat declines and fragmentation due to deforestation and the decrease of populations of Quercus species. In Colombia, around 40% of the territory has been transformed due to human population increase and changes in land use (Avella and Rangel 2017). In the Andean region, deforestation has transformed at least 60% of the areas original ecosystem, and have significantly reduced the area of Quercus humboldtti forests (Avella and Rangel 2017). Anthropogenic pressure on oak forests and habitat degradation is mainly due to deforestation due to land use change, logging, and urbanization. In addition, timber extraction carried out for the production of charcoal in the past and continued use of wood for construction of houses and furniture has significantly negatively impacted oak populations (Cárdenas and Salinas 2007, Nieto and Rodriguez 2010). There are several large mining initiatives being considered for the region, and if they come to fruition they will have a significant negative impact. There has been nearly 42% loss of Quercus humboldtii populations, and the tree has been nationally listed as Vulnerable (VU A2cd) in Colombia (Cardenas & Salinas 2007). Deforestation in Colombia has increased in recent years and is anticipated to continue into the future. Due to a policy aimed at conserving remaining natural areas, there is a lower threat level for the species in Costa Rica (MINAE et al. 2018).

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Conservation Actions

Habitat protection and management are needed. Populations of the hosts tree, Quercus humboldtii, occur in several protected sites, including the slopes of Nevados del Puracé and Huila, Parque Nacional Darién, Los Guacharos National Park, Corredor de Conservación de Robles Guantiva – La Rusia – Iguaque, and biological reserves on private land (Cárdenas and Salinas 2007). But most of the habitat is unprotected and susceptible to deforestation or degradation. Fungi are not included in Colombian conservation and biodiversity policy and laws, so work should be undertaken to try to get them included in the future. Research is needed to evaluate population trends and further document its distribution. Molecular analyses are needed for phylogenetic inference and to provide identified sequences to enable identification of environmental samples required for molecular based ecology studies. A taxonomic review of the collections deposited in the Colombian herbaria should be carried out, as there are many unidentified bolete specimens in the collections.

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Use and Trade

No uses has been reported for this species.

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Source and Citation

Vasco-Palacios, A.M., Zuluaga, M., Calle, A., Drechsler-Santos, E.R., Kossmann, T., da Cunha, K.M., Sandoval-Leiva, P. & Torres, D. 2020. Tylopilus obscurus. The IUCN Red List of Threatened Species 2020: e.T172832555A179543305. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T172832555A179543305.en .Accessed on 1 February 2024

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• Country occurrence