By Noêmia LopesAgência FAPESP – Conservative estimates put the total number of fungal species in the world at 1.5 million. Although many remain unknown, new studies in the field of mycology are increasing the knowledge on this kingdom every year. Researchers from the São Paulo Environment Secretariat’s Botanical Institute (IBt/SP) have been contributing to these efforts and have just discovered seven new species on the Paranapiacaba Biological Reserve (RBP) in Greater São Paulo.
“With every discovery, we better understand the diversity of the fungi that are found in Brazil and worldwide, the genealogical history of the group and the relationship between the organisms that comprise it. This expansion of knowledge will certainly be greater when we identify all the materials that are collected,” stated Marina Capelari, a scientific researcher at IBt/SP and coordinator of the study responsible for the discovery.
The researchers collected samples from the fungal order Agaricales, which encompasses a broad morphological variety, including those popularly known as mushrooms (the caps or basidia are the structures of sexual reproduction among Agaricales). Samples were also collected in Fontes do Ipiranga State Park (Pefi) and Cantareira State Park. Three articles have been published on the new species found in Paranapiacaba, with a description of species, combinations – species previously described under the auspices of the genus and then recombined in another – and a variation – a species that is similar to another but has some particular characteristic that distinguishes it. “New species and new combinations of Calliderma”, published in Mycologia, describes two new species (Calliderma fibulatum and C. rimosum) and proposes two new combinations (Calliderma pruinatocutis and C. tucuchense).
The article “Two new species of Marasmius section Neosessiles (Marasmiaceae) from an Atlantic rain forest area of São Paulo State, Brazil”, published in Nova Hedwigia, describes two new species: Marasmius cystidioccultus and M. plenicystidiosus.
“Inocephalus (Entolomataceae, Agaricales) from São Paulo State, Brazil”, also published in Nova Hedwigia, cites a series of discoveries regarding the genus Inocephalus: three new species (Inocephalus cervinus, I. mucronatus and I. tenuis); a variety (I. glycosmus); four new combinations (Inocephalus azureoviridis, I. cystidiophorus, I. dennisii and I. flavotinctus) and a new citation for the São Paulo Metropolitan Region (Inocephalus virescens).
Another practical result of the study was acquisition of pure cultures of several species, mainly from the Marasmius genus, which, for example, can be analyzed in applied studies that involve enzymes.
“Furthermore, the development of the project will allow for the advancement of three doctoral candidates in Agaricales taxonomy, who can continue to the future investigation of the fungi species in São Paulo State,” stated Capelari. The IBt-SP doctoral students involved in the study are Jadson José Souza de Oliveira and Fernanda Karstedt (with FAPESP fellowships) and Nelson Menolli Junior (with a CNPq fellowship).
The project developed between 2010 and 2012 began with a survey of bibliographical resources and of the material deposited in the herbarium, which was significantly reduced in the case of the Paranapiacaba Biological Reserve. Afterwards, the team went into the field, obtaining bi-weekly or monthly samples on the reserves. “The initial treatment of the material involved the macroscopic description of each sample, with photographic documentation, isolation by culturing to enable posterior molecular analyses and drying and the necessary preparation for preservation and inclusion in herbaria,” explained Capelari.
When they began the identification and complete morphological description of the fungi, the researchers surveyed both macro- and microscopic aspects of basidia (or mushrooms). For the macroscopic analyses, the focus was on the three main basidium structures: the pileo, lamella and stipe.
The pileo, the cap of the mushroom, was analyzed according to its shape, surface, consistency, margin, coloration and dimension. The lamellae, which are the blades on the lower surface of the pileo, were analyzed in accordance with the form of fixation to the stipe. The stipe, or the “foot”, of the mushroom was analyzed based on its shape, apex or base, consistency, coloration and size.
For the microscopic analysis, the team made traversal cuts in the lamellae using razorblades and observed the following structures through an optical microscope (enlarging the image by 800 times): the superior surface (type and characteristics of the hyphae), hyphae within the context of the pileo (coloration, septum, wall width and diameter), lamellar trama (arrangements and hyphae) and hymen (characteristics of basidia, basidiospores and cistidia).
“This stage of the study was lengthy and laborious, as it is not always possible visualize all of the structures in a single cut. Sometimes, it is necessary to make several cuts and measure each structure many times, from 20 to 50, to analyze the variations of the characteristics,” said Capelari.
Each new identification was achieved with the aide of identification keys and the comparison with previously published descriptions, consulting the material deposited in herbaria many times.
“DNA sequencing was also fundamental because the morphological taxonomy is not always sufficient to identify a species. Although it is not mandatory under the Code of Nomenclature, several periodicals have not accepted publication of new species without molecular confirmation,” affirmed the researcher. In this case, the main genes involved are ITS and nLSU; the former is utilized in the taxonomy of the order Agaricales and of other groups of fungi. The analysis of the sequences is conducted by computer programs.
Other support and continued research
The study also received funding from Brazilian Federal Agency for Support and Evaluation of Graduate Education (CAPES) through the Vegetal Biology and Environment Graduate Program and includes participants from foreign institutions. Jean-Marc, of the Royal Ontario Museum (Canada), supervises the foreign internship of Jadson José Souza de Oliveira. Sarah Bergemann at the Middle Tennessee State University (MTSU) (United States) supervises the foreign internship of Fernanda Karstedt.
Alfredo Justo and David Hibbett of Clark University (United States) received Nelson Menolli Junior for a short-term internship and, along with Andrew Minnis of Agricultural Research Service of United States Department of Agriculture (ARS/USDA), are contributors to publications on the Pluteus genus.
Leading taxonomy projects since her master’s thesis (begun back in 1982), researcher Marina Capelari stressed the importance of training new human resources for the continuous collection of fungi: “São Paulo State has few specialized taxonomists, and many of our forest reserves still have not been studied.”
Unlike plants that flower in every season, the formation of a basidium depends on the temperature, humidity, substrate and frequency with which each species reproduces. According to Capelari, “Certain mushrooms are found every year, whereas others cannot be collected again for more than a decade. It is impossible, therefore, to exhibit all the species of a region for a period of two years, and it is fundamental to invest in efforts for systematic collection.”
Source and Photo: Agência FAPESP, July 17th, 2013
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