Morphological and molecular identification confirms the occurrence of the rare macromycete Phaeolepiota aurea in Greece

This work reports the occurrence of the rare macromycete Phaeolepiota aurea in Fraktos Virgin Forest of the central Rhodope, which is situated at the northeast end of the Prefecture of Drama Greece. P. aurea is considered to be rare in Europe despite its widespread occurrence in several European countries. The macromycete was identified based on its morphological (macroand microscopic) characters, as well as molecular data derived from the analysis of a partial 28S nuclear ribosomal large subunit (nrLSU) rDNA barcode. To our knowledge this is the first report of P. aurea in Greece. Preliminary phylogenetic analysis using the partial nrLSU sequence further supports previous findings that showed P. aurea to be more closely related to species of the genus Cystoderma. Nevertheless, whether P. aurea belongs to the Cystoderma genus or they are closely related sister groups still remains inconclusive. 1 2nd address: Laboratory of Molecular Biology of Plants, School of Agricultural Sciences, University of Thessaly, Thessaly, Greece 124 E. TOPALIDOU & al. 2021: Phaeolepiota aurea in Greece Macromycetes constitute a large group within the kingdom of fungi. Taxonomically they are classified into two main phyla, Ascomycota and Basidiomycota, and they are commonly known as wild mushrooms due to the formation of visible fruiting bodies that emerge from the soil. Over the last 30 years scientific research on macromycete diversity in Greece has shown that the country is particularly rich in macromycete species and over 3000 species have been sporadically recorded in the county (TSAKIRIS & STARA 2016). Nevertheless, most of those data are fragmentary and the idententification of the species is based only on the morphological characteristics of the described macromycete. The clade of Agaricales, which is one of the largest monophyletic groups of the Basidiomycota, includes widespread and diverse species ranging from desert, grasslands, forests, temperate and other habitats (MATHENY & al. 2007). Within the Agaricales, the golden cap mushroom Phaeolepiota aurea (MATT.) MRE. of the monotypic genus Phaeolepiota is found throughout North America, Europe and Asia (VASAS 2004, PHILLIPS 2005). It is considered to be rare, despite its widespread distribution in Europe. To date, it has been reported to occur in UK, Ireland, Croatia, Czech Republic, Finland, France, Italy, Germany, Netherlands, Poland, Romania, Russia, Slovakia, Hungary, Ukraine, Bulgaria (VASAS 2004, BOCCARDO & al. 2008, JORDAN & al. 2017). It is common in the Alps, e.g. in Austria, Switzerland, and known from Sweden, Norway, Denmark and Portugal (GBIF 2020, https://www.gbif.org/occurrence/search? continent=EUROPE&taxon_ key=2535253). In some of these countries the species is included in their Red-Lists (e.g. Poland, Hungary, Ukraine) and its status is stated either as vulnerable or endangered. In other countries (e.g. UK) it was removed from the national Red-List despite the fact that it is assessed as widespread but rare (JORDAN & al. 2017). Phaeolepiota aurea is saprobic, prefers nutrient rich loamy soils and commonly grows in pastures under hedges, ruderal places (e.g. roads, roadsides), in woods and parks beneath beech and alder and often associated with nettles. It occurs from September to November and although it was initially listed as an edible mushroom, its consumption is not considered safe anymore, due to its high HCN content (WELLS & KEMPTON 1965). Molecular genetic studies have contributed significantly in our interpretation and classification of macromycetes and their relatives (MATHENY & al. 2006). Phaeolepiota aurea was initially described as Agaricus aureus in 1779 and later placed in several genera, e.g. Pholiota, Togaria and also Cystoderma. In addition, it has several heterotypic synonyms (www.speciesfungorum.org). According to phylogenetic and taxonomic studies it is considered to represent either an unsupported sister group or member of Cystoderma (SAAR & al. 2009). Herein, we report for the first time the occurrence of P. aurea in Greece and provide comprehensive identification in terms of morphological characteristics and barcoding data derived from part of the 28S nuclear large subunit (nrLSU) rDNA region. Materials and methods Sampling: In November 2019, a colony of approx. 15 basidiomata was spotted in Fraktos Virgin Forest of the central Rhodope, near the road, at the location with coordinates 24.483°, 41.520°and 1440 m s. m. The colony was located in a particularly dump place, beneath beech trees (Fagus) and among Petasites. Notes on macromorphological features and ecology and photographs were done in the field. Specimens were collected and brought to the lab for further studies and for genetic analysis. Morphological character examination: The macroscopic characteristics were described based on the observation of fresh specimens. For microscopic analyses, fresh and frozen (–9 °C) materials were Österr. Z. Pilzk. 28 („2019“ 2021) – Austrian J. Mycol. 28 („2019“ 2021) 125 used. Identification and descriptive terminology follows, e.g. PHILLIPS (2005). Morphological observations were carried out with a CARL ZEISS Stemi-2000-C stereomicroscope, while microscopic features were observed with a Carl ZEISS Axio-Imager A1 microscope, coupled with and Axion Vision camera. Nomenclature follows Index Fungorum (2020) and MycoBank (2020). The specimens were deposited in the herbarium collection of the Forest Research Institute (FRI) of Thessaloniki, Greece. Tab. 1. BLAST analysis of the Phaeolepiota aurea nrLSU sequence with accessions from GenBank. Identified species name Accession number Score (bits) e-value Identity (%) Phaeolepiota aurea MH876401 1489 0 100.00 Phaeolepiota aurea DQ071704 1489 0 100.00 Cystoderma superbum AM946443 1378 0 97.52 Cystoderma superbum AM946442 1378 0 97.52 Galerina triscopa MH828261 1365 0 97.28 Galerina pumila AY207204 1360 0 97.15 Galerina vexans MH828269 1360 0 97.15 Cortinarius teraturgus AF388755 1354 0 97.03 Galerina vittiformis MH828283 1349 0 96.91 Hebeloma affine FJ436324 1349 0 96.91 Hebeloma collariatum KT59156