Laetiporus squalidus sporocarps are known only from two localities in high altitude environments in the Southern-Southeastern Atlantic Forest domain of Brazil, in the Dense Ombrophilous Forest (above 700 m alt.) at São Paulo and in the Cloud Forests (Mixed Ombrophilous Forest) of Santa Catarina (above 1500 m alt.). These sites are separated by over 1,000 Km. In Santa Catarina state the species was collected on Schinus englerii (Anacardiaceae), while no substrate identification was given from the São Paulo specimens. Based on the potential area where the species can occur, there are an estimated 1000 sites each with 2-4 mature individuals. The total number of mature individuals is estimated be resulting no more than 4,000, restricted to one subpopulation.
The population is inferred to decline by at least 10-15% over the next 30 years, driven mainly by climate change and continued loss and degradation of the habitat in the Atlantic Forest due to human activity. The species is assessed as Vulnerable.
Laetiporus squalidus is a new species proposed by (Pires et al. 2016) based on molecular phylogenetic evidence and morphological characteristics. Authors suggested that the taxon could be a new genus, but maintined it as a new species in Laetiporus. A proposal for a new genus is in preparation.
Laetiporus squalidus is a wood-decaying fungus, causing brown rot. This is a very rare species, having been recorded only for three sites over four years since it has been described from the Brazilian Atlantic Forest inside São Paulo.
The species is assessed as Vulnerable in criterion C1.
Currently, Laetiporus squalidus sporocarps are known only from two localities in high altitude environments in the Southern-Southeastern Atlantic Forest domain of Brazil, in the Dense Ombrophilous Forest (above 700 m alt.) at São Paulo and in the Cloud Forests (Mixed Ombrophilous Forest) of Santa Catarina (above 1500 m alt.). These sites are separated by over 1,000 Km. In Santa Catarina state the species was collected on Schinus englerii (Anacardiaceae), while no substrate identification was given from the São Paulo specimens. It is expected that the species occurs at up to 1000 additional sites between these two localities.
There is a record of Laetiporous squalidus from New Zealand isolated as a non-fruting endophyte from Eucalyptus fastigata, an introduced species that is native to southeastern Australia. The material was identified through DNA sequencing, with only a 3 base pair difference in ITS sequence between it and examined Brazilan material
. ITS sequences alone are not always able to discriminate between unique species in this Laetiporaceae (Drechsler-Santos, pers. com.). Fungi on Eucalyptus species have been well studied worldwide and in Australasia, and no records of L. squalidus sporocarps have been found from that part of the world. Given the uncertainty of the identification and lack of data of a mature individual (it is only known from a single culture) further information is needed to determine conspecificity of the New Zealand material and its presence in Australasia. Therefore, this assessment is based only on Brazilian material
In Brazil, the species is expected to be distributed throughout the Atlantic Forest, likely restricted to montane environments in the Serra do Mar mountain range.
The species was first recorded in 2014 with three collections from São Paulo State, Brazil, in the Atlantic Forest domain. These three collections were the only known records until very recently, when a new collection was recorded in 2019 from Santa Catarina State in Southern Brazil, also in the Atlantic Forest domain (FLOR 67251). The species is expected to be distributed throughout the Atlantic Forest, likely restricted to montane environments in the Serra do Mar mountain range.
Based on the potential area where the species can occur there are an estimated 1000 sites each with 2-4 mature individuals and a total of number of mature individuals of no more than 4,000 restricted to one subpopulation.
The population is inferred to decline by at least 10-15% over the next 30 years, driven mainly by climate change and continued loss and degradation of the habitat in the Atlantic Forest due to human activity.
Population Trend: Decreasing
Laetiporus squalidus is saprobic, lignicolous, causing a brown-rot. The specimen from southern Brazil was found on Schinus englerii (Anacardiaceae), while no host information was given from the São Paulo specimens. It is known from montane environments, both in Coastal Atlantic Forests (dense ombrophilous forest) and cloud forests (with mixed ombrophilous forest).
The species is known from two localities in the Atlantic Forest domain. The Atlantic Forest deforestation rate largely declined in the last two decades. However, it was the most exploited 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 type locality is an area inside the most developed State in Brazil, and natural areas are under threat from continued expanded agricultural and urban growth. The southernmost locality, in the Atlantic Forest, is in the Cloud Forests of São Joaquim National Park, about 1,000 Km south from the type locality. 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). Although it is legally protected area for biodiversity, the area still faces many problems, such as alien species, hunting and fire. Additionally, Conservation Units in Brazil often have problems with a conflict of land use and ownership in their area, which severely compromises the effectiveness of biodiversity conservation (Rocha et al. 2010).
All of the known localities are in Conservation Areas, but the species also likely occurs in non-protected areas. The main conservation action is the continuity of the protection within conservation areas and implementation of habitat protection and management at other sites inside the Atlantic Forest in a attempt to protect the remaining fragments of the domain.
More research is needed to understand the phylogenetic position of the species. The genus Laetiporus and the family Laetiporaceae are undergoing revision by specialists, and new species and genera have been described, as well as new taxonomic combinations (Banik et al., 1998; Song & Cui, 2017). Also, more surveys are needed to understand the species distribution in Brazil. Much of Laetiporus life cycle remains unknown. Work to resolve the possible occurrence of the species in Australasia is needed. The cultured mycelium of an endophyte from Eucalyptus fastigata (ICMP 16889) from New Zealand presents a barcode sequence (rDNA ITS) almost identical (3 b.p. difference) to those of Laetiporus squalidus from Brazil. However, no mature basidiomata from Oceania were recorded. More surveys and samples from New Zealand and Australia are needed to determine if the species is established in that region, and if so, its distribution and ecology.
Banik, M.T., Burdsall, H.H. & Volk, T.J. (1998) Identification of groups within Laetiporus sulphureus in the United States based on RFLP analysis of the nuclear ribosomal DNA. 33, 9–14.
Foster, P. (2001) The potential negative impacts of global climate change on tropical montane cloud forests. Earth-Science Reviews 55(12): 73-106
Pires, R.M., Motato-Vásquez, V. & de Mello Gugliotta, A (2016). A new species of Laetiporus (Basidiomycota) and occurrence of L. gilbertsonii Burds. in Brazil. Nov. Hedwigia 102, 477–490.
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
Song, J. & Cui, B.-K. (2017) Phylogeny, divergence time and historical biogeography of Laetiporus (Basidiomycota, Polyporales). BMC Evol. Biol. 17, 102.
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