Meruliopsis cystidiata is a wood decaying fungus occurring in Brazil, with a wide distribution and severely fragmented subpopulations. It is known from one locality in the core of the Amazon Forest, Serra do Aracá State Park and two other localities over 3,500 km away, in the southern Atlantic Forest (Ryvarden 1987, Coelho et al. 2006). Its calculated Area of Occupancy is <1,000km². In areas that have been intensively sampled, the species is rarely encountered and the assumption is that it is rare throughout its range. Despite the large area of potential suitable habitat, the total population size is estimated at no more than 750 mature individuals. The forests 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 Atlantic Forest has only 28% of its original coverage remaining, and is largely fragmented (Tabarelli et al. 2010, Rezende et al. 2018). Its small population size covering a small area of occupancy and continue decline results in assessing this species as Vulnerable.
Meruliopsis cystidiata (≡Gloeoporus cystidiatus Ryvarden) is a new combination proposed by (Jung et al. 2018) based on molecular phylogenetic evidence. Gloeoporus guerreroanus G. Coelho, R.M. Silveira & Rajchenb was also shown to be conspecific with M. cystidiata.
This is a very rare species, having been recorded only for three localities over more than 30 years, since it has been described. Despite its large Extent of Occurrence (EOO), it is severely fragmented, with only two known subpopulations, one in the Amazon Rainforest, in the North of Brazil, and another, in the Southern Atlantic Forest, South of Brazil, over 3.500 km apart.
Currently, the species is known from the Serra do Aracá State Park, Amazonas, Brazil, a conservation unit in the core of the Amazon Forest, close to the Brazilian-Venezuelan border, as well as from two localities in the Atlantic Forest of southern Brazil: one from a forest fragment in Santa Maria, Rio Grande do Sul, and the other from São Joaquim National Park, a federal protected area in Santa Catarina.
The northern and southern localities are separated by more than 3,500 km, and the two southern localities are separated by 450 km, making the species severely fragmented. This disjunct distribution pattern might be explained by a past connection route between the Amazon and the Atlantic Forests during the Last Glacial Maximum, about 20,000 years ago (Ledo and Colli 2017).
The huge distance between the known subpopulations results in a large Extent of Occurrence (804,030 km²). In the known locations, individuals are clustered in 4 Km² quadrants. Based on the average distribution and numbers of individuals per site, and assuming a similar distribution throughout its range, Area of Occupancy is calculated at <1,000 km².
The species was first recorded in 1984 in the Amazon Rainforest. The two collections, from which the species was described in 1987, were the only known records until recently, when ‘Gloeoporus guerreroanus’ was described from southern Brazil (Coelho et al. 2006) and reported from two localities. This taxon has been shown to be conspecific to Merulipsis cystidiata (Jung et al. 2018), thereby expanding the distribution of M. cystidiata. In total it is known from three localities and represented by 12 collections. In the areas that have been intensively sampled, the species is rarely encountered and the assumption is that it is rare throughout its range. Because of the large area of potential suitable habitat, the total population size is estimated at no more than 750 mature individuals. Subpopulations were defined using circular buffer method with a scale of 1/10th maximum inter-point distance (Rivers et al. 2010). This resulted in two known subpopulations: one in the Amazon Forest and one in the Southern Atlantic Forest. We assume that there could be one other subpopulation in the Amazon, to the south of the Amazonas River.
The population numbers are expected to decline in the next 20 years. The Amazon Forest is undergoing rapid deforestation and facing increased fire frequency and intensity, following years of decline (INPE 2020). The forest could be approaching a tipping point, when the forest can no longer sustain its own water cycles, drastically changing into a savanna, leading to huge biodiversity losses (Amigo 2020). On the other hand, the Atlantic Forest deforestation rate has largely declined over the last two decades but is still ongoing. Only 28% of its natural coverage remains, largely composed by forest fragments and secondary forests (Tabarelli et al. 2010, Rezende et al. 2018). The southernmost location, in the Atlantic Forest, is in an area dedicated to agronomic research, mainly composed of exotic and invasive species such as Pinus, Eucalyptus and Hovenia dulcis. In this area, the species was found on Bambusa tuldoides, an exotic bamboo species. This area is prone to management and cutting, meaning that individuals could be lost in the process. The other known location was only recently discovered (2019), in the Cloud Forests of São Joaquim National Park, about 450 km northeast from the other southern location. Cloud Forests are naturally fragmented environments, and their dependence on the fog regime makes them particularly vulnerable to climate change, as changes in temperature alters the occurrence of clouds (Foster 2001).
Population Trend: Decreasing
The species is saprobic and lignicolous. In the Atlantic Forest domain subpopulation, all specimens were collected on bamboos, both native (Chusquea sp.) and exotic (Bambusa tuldoides), while in the Amazon Forest domain, specimens were found on hardwood branches of indigenous trees (Ryvarden 1987).
All three known locations are very different. The northern subpopulation is in the core of the Amazon Forest. In the Southern Atlantic Forest, the subpopulation is divided into two locations: one in the Montane Cloud Forests of São Joaquim National Park, and another in a small forest fragment of Tropical Semideciduous Forest, marked by the presence of exotic and invasive species (such as Pinus, Eucalyptus and Hovenia dulcis), dedicated to agronomic research.
The apparent host preference (hardwoods in the Amazon and bamboos in the Atlantic Forest) could represent an ongoing process of specialization, probably due to its geographical and ecological isolation, but more data are needed to better understand this relationship.
The species is known from one location in the Amazon Forest and two locations in the Atlantic Forest. In the Amazon, the known location is in an Integral Protection area, a state park with the same rules of a national park, meaning that this subpopulation is relatively secure. However, the Amazon ecosystem has been facing a rapid increase in deforestation and rate and intensity of fire, continuing after years of decline (INPE 2020). The southernmost location in the Atlantic Forest is an area dedicated to agronomic research, mainly composed of exotic and invasive species such as Pinus, Eucalyptus and Hovenia dulcis. This area is prone to management and cutting. The area is also surrounded by crop fields, which can also threaten the species in the location by pesticide and/or fertiliser leaking. The other known location is in the Cloud Forests of São Joaquim National Park. Although it is a legally protected, these areas still face many problems, such as alien species, hunting and fire. Additionally, recent political efforts were conducted to reduce the area of the conservation unit (Medida Provisória n° 852, de 2018), which could lead to an even greater loss of habitat for the species. Naturally, this protected area comprises a fragmented environment, and its dependence on the fog regime makes it particularly vulnerable to climate change, as changes in temperature alters the occurrence of clouds (Foster 2001). Finally, Conservation Units in Brazil usually have problems with the regularization of land use and ownership in their area, which severely compromises the effectiveness of biodiversity conservation (Rocha et al. 2010).
Two of the three known locations are in Conservation Units. The main conservation action required for these sites is to maintain the continuity of the protection within these areas. The other locality would benefit from the reintroduction of native bamboos, such as Chusquea and mitigate possible damage done by adjacent farmlands.
More research is needed to understand its relationship with bamboos in south Brazil. Research in unexplored areas within its predicted Extent of Occurrence (EOO), as well as adjacent countries, is needed to better understand its distribution and abundance.
This is no known use/trade.
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