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 3500 Km away, in the southern Atlantic Forest (Ryvarden 1987, Coelho et al. 2006). Its Extent of Occurrence is 804.030 Km² and its known Area of Occurrence is 12 Km². Accordingly, two subpopulations were defined and only one more is estimated to exist.
The species is assessed as Critically Endangered under criteria C2a(i) + D, having an inferred population of 36 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 yet largely fragmented (Tabarelli et al. 2010, Rezende et al. 2018). The risk of its environments make this species Endangered under criterion A3c. Finally, the restricted area of occurrence and its fragmented distribution puts the species as Endangered under criterion B2ab(ii,iii,iv,v).
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.
It is assessed as Critically Endangered [(CR) C2a(i)+D], having an inferred population of 36 mature individuals.
Currently, the species is known from Serra do Aracá State Park, Amazonas, Brazil, a conservation unit in the core of the Amazon Forest, close to the Brazilian-Venezuelan border. Also, from two localities in the Atlantic Forest of Southern Brazil: one from a forest fragment in Santa Maria, Rio Grande do Sul, and another one from São Joaquim National Park, a federal protected area in Santa Catarina.
The Northern and Southern localities are separated by more than 3500 Km, and the two Southern localities are separated by 450 Km, making the species severely fragmented.
The species Extent of Occurrence (EOO) is estimated at 804.030 Km², based on the polygon formed by the three known localities. However, the estimated Area of Occurrence (AOO) is only 12 Km².
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 species was first recorded in 1984 in the Amazon Rainforest. These two collections, from which the species was described in 1987, were the only known records until recently, when Gloeoporus guerreroanus, described from Southern Brazil (Coelho et al. 2006) and known from only two localities, was shown to be conspecific to M. cystidiata (Jung et al. 2018), expanding its distribution. This sums to a total of three known localities, and 12 collections. The species is assessed as Critically Endangered under criteria C2a(i) + D1, inferred population is of 36 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 on 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 at least 50% in the next 20 years [(EN) A3c]. The Amazon Forest is facing a 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). On the other hand, the Atlantic Forest deforestation rate largely declined on the last two decades. However, it was the most explored ecosystem during Brazil’s colonization, and 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 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 the individuals could be extinct in the process. The other known location where the species occurs was only recently discovered (2019), in the Cloud Forests of São Joaquim National Park, about 450 Km northeast from the other southern location. The Cloud Forests are a naturally fragmented environment, 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).
The huge distance between the known subpopulations results in a large Extent of Occurrence (804.030 Km²). However, the species known Area of Occupation within this EOO is of only 12 Km². Assuming the existence of 3 subpopulations with the same average AOO of the three known, the resulting AOO would be of 16 Km². The reduced Area of Occupation, coupled with the severely fragmented population and the potential loss of habitat quality, make the species Endangered [(EN) B2ab(ii,iii)].
Population Trend: Decreasing
Saprobic, 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 (Ryvarden 1987).
All three known locations of occurrence are very different. The northern subpopulation represents one of the locations 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 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 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. In this area, the species was found in Bambusa tuldoides, an exotic bamboo species. This area is prone to management and cutting, meaning that the individuals could be extinct in the process. The area is also surrounded by crop fields, which can also threaten the species in the location by pesticide and/or fertilizer leaking. The other known location is in the Cloud Forests of São Joaquim National Park. Although it is a legal area for full protection of biodiversity, there are still faces many problems, such as alien species, hunting and fire, for example. 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 their dependence on the fog regime makes them particularly vulnerable to climate changes, as changes in temperature alters the occurrence of clouds (Foster 2001).
Finally, Conservartion Units in Brazil usually have problems with the regularization of land use and ownerships 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, regarding these, the main conservation action is the continuity of the protection within these areas. The other locality, however, needs to be restored with native trees and have its quality assured by mitigation of possible damage done by adjacent farmlands.
More research is needed to understand its relationship with bamboos in the South Brazil. Also, the maintenance of research in unexplored areas, within its Extent of Occurrence (EOO), can help to better understand the distribution, so far known as disjunct, as well as confirm this as an extremely rare species.
Amigo, I. (2020) When will the Amazon hit a tipping point? Nature 578, 505-507. doi: 10.1038/d41586-020-00508-4
Coelho, G., da Silveira, R. M. B., & Rajchenberg, M. (2006) A new Gloeoporus species growing on bamboo from southern Brazil. Mycologia 98(5), 821–827. doi:10.3852/mycologia.98.5.821
Foster, P. (2001) The potential negative impacts of global climate change on tropical montane cloud forests. Earth-Science Reviews 55(12): 73-106
Jung, P.E., Lee, H., Wu, S.H., Hattori, T., Tomšovský, M., Rajchenberg, M., Zhou, M. Lim, Y.W. (2018) Revision of the taxonomic status of the genus Gloeoporus (Polyporales, Basidiomycota) reveals two new species. Mycological Progress 17(7), 855–863. doi:10.1007/s11557-018-1400-y
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.
Medida Provisória n° 852, de 2018 (Gestão de imóveis da União) - Medidas Provisórias. Congresso Nacional. Available at https://www.congressonacional.leg.br/materias/medidas-provisorias/-/mpv/134252
Ledo, R.M.D., Colli, G.R. (2017) The historical connections between the Amazon and the Atlantic Forest revisited. Journal of Biogeography, 44(11), 2551–2563. doi:10.1111/jbi.13049
Rezende, C.L., Scarano, F.R., Assad, E.D., Joly, C.A., Metzger, J.P., Strassburg, B.B.N., Tabarelli, M., Fonseca, G.A., Mittermeier, R. A. (2018) From hotspot to hopespot: An opportunity for the Brazilian Atlantic Forest. Perspectives in Ecology and Conservation. doi:10.1016/j.pecon.2018.10.002
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
Rocha, L. G. M. da, Drummond, J. A., & Ganem, R. S. (2010). Parques nacionais Brasileiros: problemas fundiários e alternativas para a sua resolução. Revista de Sociologia e Política, 18(36), 205–226. doi:10.1590/s0104-44782010000200013
Ryvarden, L. (1987) New and noteworthy polypores from tropical America. Mycotaxon 28(2):525-541
Tabarelli, M., Aguiar, A. V., Ribeiro, M. C., Metzger, J. P., & Peres, C. A. (2010) Prospects for biodiversity conservation in the Atlantic Forest: Lessons from aging human-modified landscapes. Biological Conservation, 143(10), 2328–2340. doi:10.1016/j.biocon.2010.02.005