New species of corticioid fungi (Basidiomycota) for Poland found in Białowieża Primeval Forest in 2018‒2020

Eight new species of fungi ( Acanthobasidium norvegicum , Amylocorticium laceratum , Hyphoderma transiens , Odonticium septocystidiatum , Phlebia cretacea , Ph. subulata , Steccherinum albidum , and Tubulicrinis calothrix ) were identified for Poland after a study of collections from large forests situated in the northeast part of the country. Leptosporomyces fuscostratus was confirmed for Polish mycobiota. Main diagnostic features, natural range, substratum preferences, and taxonomic position of these species are discussed. Color images of basidiomata for 9 species, line drawings of m icroscopic structures for 6 species, and scanning electron microscopy images of important microstructures for 4 species are provided .


Introduction
Corticioid fungi is an artificial assemblage of the species from the phylum Basidiomycota and class Agaricomycetes, characterized by effused or effused-reflexed basidiomata, one-celled basidia, and hymenophore of various configurations, from smooth to raduloid and reticulately folded, but excluding poroid and lamellate types. Many of these fungi have flat, thin fruitbodies, that develop on dead wood in all seasons, excluding frost periods. They are considered by mycologists as a separate group, accepted historically on the basis of similar macromorphology of basidiomata, ecology, and methodical approaches for study of species. We accept a brief definition of corticioid fungi (Yurchenko, 2020) as non-poroid resupinate Aphyllophorales, following Jülich and Stalpers (1980), and including one genus of Tremellomycetes, Syzygospora. The latter has a peculiar morphology of basidia, resembling true homobasidia, and the ability of some species to develop very small film-like basidiomata. We also belong Dentipratulum, a genus with hydnoid hymenophore, to corticioid fungi, because its fructifications have scarce subiculum (see Holec & Zehnálek, 2021).
Species diversity of corticioid fungi in Poland is relatively well studied. The monograph by Wojewoda (2003) is the most recent catalogue of the all the larger basidiomycetes, found in Poland. It includes 293 species of corticioid fungi as defined above. However, new species are recorded almost every year for the country.
Białowieża Primeval Forest is one of the largest and best-preserved non-montane deciduous forest massif in Europe (Bobiec, 2002). It is an area of particular interest for mycologists (Ruszkiewicz-Michalska et al., 2021) due to its old-aged ecosystems, scarcely modified by human activity, that include both nemoral (associated with e.g. Quercus robur) and boreal (associated with Picea abies and Pinus sylvestris) elements of biota. Larger basidiomycetes have been studied here since 1826, but a monographic treatment of corticioid fungi has not been realized yet (see Kujawa et al., 2018).
In the present paper we give the characteristics of some new species thereby adding to the list of Polish fungi.

Material and Methods
The new species for Polish mycobiota were identified after microscopic examination of 540 specimens of corticioid fungi, stored in the herbarium of Institute of Forest Sciences, Białystok University of Technology (BLS, Hajnówka). These specimens were collected by Marek Wołkowycki from the northeast part of Poland, in the period 1993-2022; most collections belong to the years 2018-2020. About 95% of the specimens examined were collected in Białowieża Primeval Forest (southeast part of Podlaskie voivodeship), 1% in Knyszyn Primeval Forest (central-east part of Podlaskie voivodeship), and 4% in Piska Primeval Forest (southeast part of Warmińsko-Mazurskie voivodeship).
Macro-and micromorphology was studied on dry basidiomata. The pictures of fresh basidiomata of some species taken soon after their collection were also used to document macromorphology. For microscopic slides, vertical hand sections of the basidiomata were rehydrated in 3% aqueous potassium hydroxide (abbreviated as KOH in the text). Incrustations on hyphae and hymenial elements and amyloid reaction of basidiospores were studied in Melzer's reagent, wherever necessary. Microscopic measurements were done on Nikon Eclipse Ni-U light microscope (Nikon Corp., Japan), mostly under ×1000 magnification, by NIS-Elements Br imaging software (Nikon Corp.). Spore quotient (Q) was determined as length/width ratio for individual spores.
Scanning electron images of selected microstructures of the fungi were obtained on Phenom G2 pro desktop microscope (Labmate, UK). For these images, pieces of fruitbodies were taken from the herbarium, glued to metallic stands using double-sided adhesive film, and coated with 3.1-3.2 nm layer of gold in a Leica EN ACE200 vacuum coater (Leica Microsystems, Germany).
To confirm that a species was not published for the country before, we used the checklist of Wojewoda (2003), and a checklist in the resource grzyby.pl (Snowarski, 2022). Some additional data on species distribution were taken from the Global Biodiversity Information Facility (https://www.gbif.org).

Results
The study revealed that eight species of fungi identified by us had not been published in articles or monographs for Poland earlier. Besides, we found that one species, Leptosporomyces fuscostratus, required clarification of its status in Polish biota. The data about these species are given below. The species is distinguished by the following main features: poorly developed subiculum (10-25 μm thick); numerous subcylindrical or fusoid cystidia, having pale brownish-yellow granular or resinous contents in water and KOH; presence of acanthophyses; (1)2-sterigmate basidia; large (9-12 μm long) amyloid basidiospores, covered by warts, easily observable in Melzer's reagent. Some basidia have scarce, short lateral protuberances in their lower half. Occasional basidia have a transverse secondary septum. The acanthophyses of this fungus resemble basidia in shape. Our specimen exhibited mostly 2 apical protuberances on acanthophyses, whereas in pictures published by other authors (Larsson & Ryvarden, 2021;Martini, 2016) the number of protuberances reached 4-7. Spores of this fungus look almost smooth in KOH.
This species is distributed in Western Europe, from Norway and Sweden to Portugal (Bernicchia & Gorjón, 2010;Eriksson & Ryvarden, 1973). Our locality is the easternmost known for the species.
The usual substrata for this species are dead Calluna stems and twigs (Eriksson & Ryvarden, 1973). The fungus was reported on Rubus in France (Wu et al., 2001).
The species has Eurasian distribution from Norway and Sweden to Spain and Turkey (Bernicchia & Gorjón, 2010;Eriksson & Ryvarden, 1973), as well as in the distant parts of the range in North Urals (Kotiranta & Penzina, 1998) and China (Dai, 2011). Its occurrence is rare in all parts of its natural range (Hjortstam, 1980). The fungus called Athelopsis lacerata   was reported by Gates (2009) from Tasmania, but the identity of the Tasmanian material with this taxon is difficult because of large geographical disjunction.
A number of authors put this species in the genus Amylocorticium because of the amyloid spore wall (Hjortstam, 1980;Hjortstam & Ryvarden, 1979;Larsson & Ryvarden, 2021). Molecular data (Binder et al., 2010) confirmed its phylogenetic position in the order Amylocorticiales. However, its generic position is not yet clear; DNA sequences show its relation to Amyloxenasma, whereas basidia and spore shape have similarity with Melzericium.
The fungus grows saprobically mostly on hardwood (Fagus, Quercus), and has also been recorded on Tilia, Cornus (Bernicchia & Gorjón, 2010;Volobuev & Arzhenenko, 2018), and Ulmus (Shiryaev et al., 2010). Our specimens indicate a distinct preference of this fungus to the dead wood of Tilia cordata in Tilio-Carpinetum forest association in the study area.
The fungus under the name L. fuscostratus was published for Poland only once by Karasiński et al. (2015), from Kampinos and Białowieża national parks. In this source Confertobasidium olivaceoalbum (Bourdot & Galzin) Jülich is noted as a synonym of L. fuscostratus. However, after the publication by Ginns and Lefebvre (1993), the current name accepted for C. olivaceoalbum is Scytinostromella olivaceoalba (Bourdot & Galzin) Ginns & M.N.L. Lefebvre. The latter is a fungus, having rare skeletal hyphae and fusiform gloeocystidia in hymenium (Bernicchia & Gorjón, 2010). Both types of elements were not observed in our specimen, and hence we address it as L. fuscostratus, and confirm this species for Polish mycobiota. The species' natural range includes Europe (Norway, Sweden, Finland, Estonia, France, Belgium; Bernicchia & Gorjón, 2010) and North America -Canada and USA, where it is rare (Ginns & Lefebvre, 1993). An isolated locality in the southern pre-Urals was also reported to

P O S T P R I N T
Vol. 57, Article 577 DOI: 10.5586/am.577 Acta Mycologica: Postprint Version have this species (Safonov, 2015). There are four records of this species for Poland in GBIF, based on specimens in GB herbarium, collected in 1973: GB-115560, 115561, 115562, 115563.

Phlebia subulata J. Erikss. & Hjortstam
The natural range of this fungus includes Europe (from Norway and Finland to Spain, Serbia, and Ukraine; Bernicchia & Gorjón, 2010), and Middle Siberia . This species has been reported from Belarusian part of Białowieża Primeval Forest (Yurchenko, 2020). There is a record of the species from Poland in GBIF, based on a specimen from GB herbarium GB-118046, collected in 1973.
The fungus grows on fallen wood of gymnosperms (Picea, seldom Pinus), and is associated with primeval coniferous forests with Hylocomium and Vaccinium (Eriksson et al., 1981). Our specimen was found in a broadleaved forest with admixture of Picea.
The distributional range of the species includes the type locality in Britain, on dead wood of Fagus (Legon & Roberts, 2002), and two localities in Switzerland (GBIF data, occurrences SWISSFUNGI-CH-633787 and -744524). Moreover, a specimen published under the name Steccherinum albidum aff. was found in Mexico (Spirin & Ryvarden, 2016); it has larger spores, than in the European material.  The species is distinguished by lyocystidia, which have apically asymmetrically thickened wall, and often bear a cap of crystals that are partially dissolvable in KOH. Some amount of cystidia have symmetrical wall thickening; sometimes this symmetry depends on cystidium projection on microscopic slide. Thus for reliable species identification, at least 20 cystidia should be studied. The species has hemicosmopolitan distributional range, with a preference for warmtemperate regions. Type locality of it is in Tunisia, North Africa . In Europe it is known to be found from Norway and Finland to Portugal, Italy, and Greece (Bernicchia & Gorjón, 2010). Asian part of the range includes Turkey (Bernicchia & Gorjón, 2010), Middle Urals (Shiryaev et al., 2010), Middle and East Siberia Kotiranta et al., 2016;, Primorye (Viner & Kokaeva, 2017), China (Dai, 2011), and Japan (Maekawa, 2021). In North America it is known to occur in Canada and USA (Ginns & Lefebvre, 1993). Other regions where the species was found include Canary Islands (Beltrán-Tejera et al., 2013), Venezuela (Liberta & Navas, 1978), Hawaii (Gilbertson et al., 2001), and Réunion (Hjortstam & Ryvarden, 2007). There were 7 records of this species in GBIF, belonging to Poland, based on specimens in GB herbarium and collected in 1973: GB-100377, 100378, 100379, 100380, 100381, 100382, 100383.

Discussion
The number of species of the fungi within a country is not a fixed value, since new species are added almost every year to the country list. This can be attributed to inclusion of new areas for collection, thorough examination of habitats, studying more herbarium material, taking into account new taxonomic publications, growth of taxonomic experience of mycologists, and supposedly also expansion of the natural ranges of the species due to changes in environment. The effectiveness of the process of studying corticioid fungal diversity in Poland can be evaluated from our data. Most of the herbarium material from this study was collected during three years and only from three forested areas in the northeast part of the country. The research added eight species to the biota: Acanthobasidium norvegicum, Amylocorticium laceratum, Hyphoderma transiens, Odonticium septocystidiatum, Phlebia cretacea, Ph. subulata, Steccherinum albidum, and Tubulicrinis calothrix, which constitutes about 3% of the total corticioid fungal diversity known in 2003 (Wojewoda, 2003). The specimens of new species constitute 2.2% of the total number of collections examined. All nine species described in this paper were found in Białowieża Primeval Forest, but they are still not recorded in Knyszyn and Piska Primeval Forests. It should be noted, that all nine species were found out of the borders of Białowieża National Park, a core of Primeval Forests, which is a special protected area with strict regulation for collecting fungi. From the nine species described above, only Phlebia subulata was known from the Belarusian part of Białowieża Primeval Forest.
We have found that the records of five species from Poland (Hyphoderma transiens, Leptosporomyces fuscostratus, Phlebia cretacea, Ph. subulata, Tubulicrinis calothrix) were added earlier in the GBIF database (https://www.gbif.org). All of them were based on specimens from GB herbarium (University of Götheborg, Sweden). We confirmed these species from the recently collected original material.
From nine species discussed, six (Amylocorticium laceratum, Hyphoderma transiens, Leptosporomyces fuscostratus, Odonticium septocystidiatum, Ph. subulata, Tubulicrinis calothrix) have Eurasian or broader distribution range and three (Acanthobasidium norvegicum, Phlebia cretacea, Steccherinum albidum) have European or Euro-American distribution. Two species (Hyphoderma transiens, Odonticium septocystidiatum) occur predominantly in warm-temperate regions belonging to nemoral and mediterranean biomes. Along with identified species, about 14% of the studied specimens still belong to unclear material without specific and sometimes without generic epithet, and suggests the need for further biodiversity studies.