An outlook on the diversity of polypores shared between Iran and the Mediterranean area

INTRODUCTION

Poroid fungi (polypores) are an important group of wood-inhabiting macrobasidiomycetes that have significant roles in biomass recycling in forests and woodland ecosystems. Several species are bio-indicator of areas with high conservation value, and a considerable number of species possess bioactive compounds with diverse biotechnological and pharmaceutical applications (Grienke et al. 2014).

Among territories in southwestern Asia, Iran retains the richest flora and fauna and the highest level of plant endemism (Zohary 1973, Akhani 2006, Noroozi et al. 2018). Comparative figures on the mycota in southwestern Asia are less available. At least for polypores and corticioids, species diversity in Iran seems to be higher than most of the territories in the region (Ghobad-Nejhad et al. 2009, Ghobad-Nejhad & Hallenberg 2012). The forest coverage in Iran is very low, comprising less than 10% of the total area of the country, and is confined to the southern Caspian Sea forests (Hyrcan) as well as Zagros forests in western Iran (Sagheb-Talebi et al. 2014). Hyrcanian forests are the southernmost part of one of the northern Hemisphere biodiversity hotspots 'the Caucasus region', harboring glacial refugia with several relict plants (Röhrig 1991). In a survey on the composition of corticioid fungi in the Caucasus region, it has been shown that this region has possibly contributed as a source of fungal colonization in Europe after Pleistocene glaciations (Ghobad-Nejhad et al. 2012). Recently, Ordynets et al. (2018) concluded that the mean species richness of aphyllophoroids (mostly polypores and corticioids) in Hyrcan almost equals to that of Mediterranean Europe.

Accounts on diversity of polypores in Iran have been documented in studies on wood fungi by Hallenberg (1981), later updated by Ghobad-Nejhad & Hallenberg (2012). Amoopour et al. (2016) provided a checklist for polypores in Gilan province. However, comparative studies on the pattern of geographical distribution of the polypore species in Iran are lacking. In the present study, we made comparisons between the polypore composition in Iran and the Mediterranean area, also taking adjacent territories in the Caucasus region into account. The Caucasus region comprises southwestern Russia, Georgia, Azerbaijan, Armenia, eastern Turkey, and northern Iran (Ghobad-Nejhad et al. 2009). The Mediterranean area and Iran both embrace some of the remaining north temperate glacial refugia which have been crucial for revival of the north hemispheric biota after the last glacial maxima (Taberlet et al. 1998, Tarasov et al. 2000).

MATERIALS and METHODS

The core analysis in this study is based on the most recent account of polypores of the Mediterranean region by Bernicchia & Gorjón (2020), list of Iranian wood-inhabiting basidiomycetes (Ghobad-Nejhad & Hallenberg 2012) and intensive field records by the authors. Moreover, the general distribution pattern for each species (categorized as widespread or common, northern European, southern-central Europe, Mediterr
anean, tropical/subtropical, and extra European species) was extracted from various published works including Ryvarden & Melo (2014), Dai (2012), and Ghobad-Nejhad (2011). Rare refers to species which are known by small number of records and their distribution pattern in Europe is not clear. Nomenclature mostly follows Mycobank (www.mycobank.org, accessed August 2019).

RESULTS

Polypore shared species between two areas

The most recent account of polypores of the Mediterranean region (Bernicchia & Gorjón 2020) enumerates ca. 372 species for this area. In Iran, a total number of 132 polypore species are present (updated list unpublished) from which, 115 polypore species (87%) are shared with the list of polypores for the Mediterranean region (Fig. 1). In other words, 31% of polypores in the Mediterranean region are also present in Iran.

As shown in Fig. 1, more than half of the shared species (59%) are widespread or are very-to fairly common in Europe. Twenty-three species (18%) are central to southern-central European, north European, or rare. Seven species (5%) are extra European, and 5% are 'true' Mediterranean species. Widespread species are not discussed here, but selected species from other distribution categories are mentioned in the following paragraphs. Cinereomyces lindbladii (Berk.) Jülich and Inonotus obliquus (Ach. ex Pers.) Pilát are mostly distributed in northern Europe, while Ceriporiopsis gilvescens (Bres.) Domanski is generally distributed in central Europe. Species belonging to southern to south- -central in Europe include: Ceriporia excelsa (S. Lundell) Parmasto, Fuscoporia torulosa (Pers.) T. Wagner & M. Fisch., Ganoderma australe (Fr.) Pat., Ganoderma resinaceum Boud., Gloeophyllum trabeum (Pers.) Murrill, Inonotus nidus-pici Pilát ex Pilát, Inocutis tamaricis (Pat.) Fiasson & Niemelä, and Oligoporus simanii (Pilát ex Pilát) Bernicchia. Rare but scattered species in Europe are Datronia stereoides (Fr.) Ryvarden, Gloeoporus pannocinctus (Romell) J. Erikss., Steccherinum lacerum (P. Karst.) Kotir. & Saaren., and Rhodonia placenta (Fr.) Niemelä, K.H. Larss. & Schigel. Rare species include: Daedaleopsis tricolor (Bull.) Bondartsev & Singer, Inonotus krawtzewii (Pilát) Pilát, Metuloidea fragrans (A. David & Tortic) Miettinen, Odoria alborubescens (Bourdot & Galzin) V. Papp & Dima, Oligoporus simanii (Pilát ex Pilát) Bernicchia, Perenniporia narymica (Pilát) Pouzar, Trametes warnieri (Durieu & Mont.) Zmitr., Tyromyces kmetii (Bres.) Bondartsev & Singer, and Tyromyces fissilis (Berk. & M.A. Curtis) Donk. Few species can be regarded as extra European: Inocutis levis (P. Karst.) Y.C. Dai is a central Asian species, and Amylosporus campbellii (Berk.) Ryvarden is subtropical. Moreover, Antrodia malicola (Berk. & M.A. Curtis) Donk, Ceriporia alachuana (Murrill) Hallenb., Loweomyces fractipes (Berk. & M.A. Curtis) Jülich, Dichomitus squalens (P. Karst.) D.A. Reid, and Pyrofomes demidoffii (Lév.) Kotl. & Pouzar are almost absent in Europe but widespread in North America or East Asia. Finally, Antrodia serpens (Fr.) P. Karst., Ceriporia aurantiocarnescens (Henn.) M. Pieri & B. Rivoire, Fomitiporia rosmarini (Bernicchia) Ghobad-Nejhad & Y.C. Dai, Fomitopsis iberica Melo & Ryvarden, Fomitopsis spraguei (Berk. & M.A. Curtis) Gilb. & Ryvarden, and Trametes ljubarskyi Pilát species seem to be predominantly distributed in the Mediterranean Europe or are 'true' Mediterranean.  Phellinus rimosus (Berk.) Pilát also takes a Mediterranean distribution in Europe, yet is widespread in Eurasia, Africa, and Australia (Hattori et al. 2014).

Fig. 1. Sunburst chart presenting the absolute numbers and proportion of polypore species shared between Iran and the Mediterranean region. Out of total number of polypores in Iran (132 species), 87% are shared with the Mediterranean region from which, 59% are widespread species, 5% are extra European, 5% are 'true' Mediterranean species, and 18% are central to southern-central European, north European, and rare (marked as ‘other’ in this chart). Only 13% of Iranian polypores are not shared with the Mediterranean region.

Fig. 2. In situ basidiocarp photos of some polypore species discussed in the text. a. Inocutis levis (coll. Ghobad-Nejhad, in 2016); b. Inonotus krawtzewii (coll. Ghobad-Nejhad, in 2015); c. Fomitiporia rosmarini (Bernicchia 1464); d. Fomitopsis iberica (Cartabia 3142); e. Fomitopsis spraguei (Bigelow, June 2017); f. Trametes ljubarskyi (Botyakov 3627). Photos: Ghobad-Nejhad (a, b), Bernicchia (c–f).

Notes on remarkable shared species

Amylosporus campbellii (Berk.) Ryvarden

This is an extra European species mostly distributed in tropical-subtropical regions, and was only recently recorded in Sicily by Bernicchia et al. (2017). The species was recorded as associated with a graminaceous plant in southern Iran (Saber & Minassian 1998), a place located in Saharo-Sindian floristic region influenced by a tropical climate.

Ceriporia alachuana (Murrill) Hallenb.

This is a temperate to subtropical species dominantly distributed in southern North America and eastern Asia (Dai 2012), and only seldom reported in Europe. Three collections were reported by Hallenberg (1979) from northern Iran who at that time, assigned them as the first record of the species outside North America.

Ceriporia aurantiocarnescens (Henn.) M. Pieri & B. Rivoire

This is a rare species recorded only from few Mediterranean countries. In Asia, this species has been sporadically reported from Georgia, China, and was recently reported by Amoopour et al. (2016) from Iran. The salmon to later becoming vinaceous pore surface is striking in this species.

Inocutis levis (P. Karst.) Y.C. Dai     Fig. 2a

This is apparently a central Asian species growing on different hardwoods, and has not been recorded in Europe. In Iran, it grows successfully on planted Platanus orientalis L. and Ulmus glabra in urban areas in central Iran, and seems to be well-adapted to air-polluted metropolitans (Ghobad-Nejhad & Kotiranta 2008, Hashemi et al. 2017).