Thamnomyces chamissonis Ehrenb. was the first xylarioid species described from Brazil, in 1820 (Poroca, 1986). “Thamno”, from Greek, means bush, so the genus etymology refers to the arbuscular (dendroid) morphology of the stroma in the type specimen, which is dichotomically branched at the apices. The species T. chamissonis was named in honour of Adelbert von Chamisso, a German naturalist who collected the type specimen in 1815 in the State of Santa Catarina, Southern Brazil. Dennis (1957) considered Thamnomyces macrospora Lloyd, described in 1920 based on Brazilian specimens collected by Möller, a synonym.
Despite the dark color of stromata, they are conspicuous because usually they grow gregarious.

It is an endemic species from Brazil, with a restricted distribution in a threatened environment (coastal areas of Atlantic Rainforest, especially in Southern Brazil).

RED LIST JUSTIFICATION
There are records of Thamnomyces chamissonis from 11 sites from the Atlantic Forest, but it is likely to be more widespread in fragmented forest remnants. The current total population is estimated at 15,000-29,000 mature individuals, in one subpopulation. Based on the severe habitat decline within the area, we suspect a population decline of around 25% in the last three generations (50 years). Thamnomyces chamissonis is assessed as Near Threatened NT A2c+3c.

Thamnomyces chamissonis is currently known from the Atlantic Forest from Brazil. Records from Northern Brazil and other countries (Peru) are probably a misidentification of T. dendroidea (Stadler et al. 2010) or taxa unknown from science.
Thamnomyces chamissonis is probably more common in the subtropical areas of Atlantic Forest, since most records are from the State of Santa Catarina (7 collections). However, there are also a few scattered records from the States of Paraná (3 collections), São Paulo (2 collections), and Bahia (1 collection) (Poroca, 1986; Meijer, 2006; Loguercio-Leite et al. 2009; Pereira, 2011; Silva; 2019; SpeciesLink, 2021). One report from Minas Gerais (Chardon et al., 1940) could not be confirmed. Most records are from forest areas near the coast (no more than 30 km far away), and two collections are around 70 km from the coast.

There are 13 known collections of the species deposited in fungaria. This is a species with medium to high detectability. Stromata are dark colored, but they grow gregarious, therefore, they are not difficult to find in the field if someone is looking for wood-decomposing fungi.
The species is known from 11 sites, but it is expected to be distributed along the Atlantic Forest in the dense ombrophilous forest near the coast, especially in Southern and Southeastern Brazil, with 250-500 additional potential sites. Its population is estimated ca. 15,000-29,000 mature individuals [(13 collections/11 known sites)*10 multiplied factor*5 ramets*250-500 potential sites], restricted to one subpopulation.
The Atlantic Forest has been deforested over decades, and the remaining fragments are suffering from biomass and biodiversity erosion. The Atlantic Forest is one of the most fragmented tropical/subtropical forests in the world, and only around 28% percent of the original forest in Brazil is left, much of it in small, unconnected fragments (Rezende et al., 2018).
Population decline was estimated in light of extensive loss of suitable habitat (Rezende et al., 2018) and the putative influence that habitat degradation has on species occupation in a given environment (Berglund & Jonsson, 2003; Haddad et al., 2015). Based on this information, we precautionarily assume there has been a habitat loss of at least 25% within the past three generations (50 years) and that this also equates to a population decline of the fungus of at least 25% within this timeframe.

Thamnomyces chamissonis is a saprotrophic species and grows on dead trunks (or large fallen branches). Its distribution is restricted to the now fragmented and scattered Atlantic Forest (Ombrophilous Dense Forest), especially near coastal areas. Since the species occurs on large woody substrata, we estimate that three generations = 50 years.

The Atlantic Forest as a whole suffers for decades with deforestation through the extraction of timber, intensive land use, urban expansion, industrialization and fuelwood harvesting; as well as tourism development, mining, roads infrastructure and introduction of alien species, such as Eucalyptus and Pinus spp. Only 28% of its natural coverage remains, largely composed of small forest fragments and secondary forests (Tabarelli et al. 2010, Rezende et al. 2018).
The coastal Atlantic Forest coincides with the area occupied by the majority of the Brazilian population, and as a result, is considered one of Brazil’s most impacted environments, with high rates of habitat loss, especially by urban development, persisting to the present day.
Most records of Thamnomyces chamissonis are from the type locality, and the main threats in this area are: urban expansion; real estate speculation in coastal areas; predatory tourism; pollution from the disposal of garbage and even effluents; deforestation and fires; vehicle traffic; the presence of exotic plant species.

The main action to preserve the species is the protection of its habitat and creation of new conservation areas to harbor the probable microhabitats to which the Atlantic Forest may be restricted in the future. Also, measures must be taken to assure that the protected Atlantic Forest areas reach a mature state.

Probably the diversity of Thamnomyces species is larger than we know, including new taxa from Northern and Northeastern Brazil. Two species with dendroid stroma are very similar (T. chamissonis and T. dendroidea), so careful analysis is necessary to determine the species and to confirm identification from herbarium specimens. Moreover, further studies are necessary to better understand the species distribution, ecology and population trends.

None known.

Berglund, H. and Jonsson, B.G. 2005. Verifying an extinction debt among lichens and fungi in northern Swedish boreal forests. Conservation Biology 19(2): 338–348.

Chardon, C.E., Miller, J.H. and Muller, A.S. 1940. Ascomycetes from the State of Minas Geraes (Brazil). Mycologia 32(2): 172–204.

Dennis, R.W.G. 1957. Further notes on tropical American Xylariaceae. Kew Bulletin 2: 297–332.

Haddad, N.M., Brudvig, L.A., Clobert, J. et al. 2015. Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances 1: e1500052.

Loguercio-Leite, C., Campos-Santana, M., Gerlach, A., Guthjar, M., Trierveiler-Pereira, L.,  Drechsler-Santos, R. and Baltazar, J.M. 2009. Sinopse de macromicetes em Santa Catarina, Brasil. Insula 38: 1–14.

Meijer, A.A.R. 2006. Preliminary list of the macromycetes from the Brazilian state of Paraná. Boletim do Museu Botânico Municipal, Curitiba 68: 1–55.

Pereira, J. 2011. Xylariaceae (Ascomycota) em áreas de Mata Atlântica nordestina e em herbários brasileiros. Tese de Doutorado. Programa de Pós-Graduação em Biologia de Fungos, Universidade Federal de Pernambuco, Brasil.

Poroca, D.J.M. 1986. Revisão histórica das Xylariaceae do Brasil. Boletín Micológico 3(1): 41–53.

Rezende, C.L., Scarano, F.R., Assad, E.D., Joly, C.A., Metzger, J.P., Strassburg, B.B.N., Tabarelli, M., Fonesca, G.A. and Mittermeier, R.A. 2018. From hotspot to hopespot: An opportunity for the Brazilian Atlantic Forest. Perspectives in ecology and conservation 16: 208–214.

Silva, C.S. 2019. Fungos Xylariaceae e Hypoxylaceae (Ascomycota) em cultivos de cacaueiros sombreados nos municípios de Ilhéus e Ibirataia, sul da Bahia. Dissertação de Mestrado. Programa de Pós-Graduação em em Produção Vegetal, Universidade Estadual de Santa Cruz, Brasil.

SpeciesLink. 2021. Available at: https://specieslink.net/. (Accessed: 29 September 2021).

Tabarelli, M., Aguiar, A.V., Ribeiro, M.C., Metzger, J.P. and Peres, C.A. 2010. Prospects for biodiversity conservation in the Atlantic Forest: Lessons from aging human-modified landscapes. Biological Conservation 143(10): 2328–2340.