Checklist of aphyllophoroid fungi ( Agaricomycetes , Basidiomycota ) in boreal forests of the Solovetsky Archipelago ( Arkhangelsk Region , European Russia )

Herein we present a checklist of aphyllophoroid fungi of the Solovetsky Archipelago, located in the White Sea (Arkhangesk Region, European Russia). The annotated list contains 275 species belonging to 139 genera of aphyllophoroid basidiomycetes (Agaricomycetes, Basidiomycota). Eight species (Athelia bombacina, Ceraceomyces tessulatus, Clavariadelphus truncatus, Clavaria zollingeri, Clavulinopsis luteoalba, Hyphoderma obtusiforme, Phanerochaete jose-ferreirae, and Ramaria obtusissima) are recorded from the Arkhangelsk Region for the first time, and 23 species were recorded for the first time from the Solovetsky Archipelago. Most records are documented by herbarium specimens.


Introduction
The aphyllophoroid fungi (Agaricomycetes, Basidiomycota) represent a key element of boreal ecosystems due to their wood-decaying and litter-decomposing abilities.Some species also are capable of ectomycorrhiza formation (Köljalg et al. 2000, Rinaldi et al. 2008).However, their diversity in boreal forests is little known over large areas.The present checklist intends to cover the biodiversity of this ecomorphic group of basidiomycetes on the territory of the Solovetsky Archipelago, where oldgrowth boreal forests have a local mosaic distribution.Such forests are enriched by fallen coarse dead wood on various stages of decomposition and by fine woody debris, and therefore, a lot of niches for wood-inhabiting fungi are available.

LIST OF SPECIES
average July temperature is 12.9 °C, whereas in February it is -10.1 °C.The sum of active temperatures varies around 889° (Ipatov et al. 2005).
The vegetation of Archipelago combines north taiga and forest tundra features.The forests occupy ca 67% of the area (Gryaznov and Sokolov 2008), and most of them were not cut within the last 90 years.Forest cutting in the 1920s to '30s, as well as forest fires, had an impact on the age structure and species composition of the forest stands (Ipatov et al. 2005).Norway spruce (Picea abies/ obovata) dominates on silty soils (occupying ca 42.1% of the forested area), and Scots pine (Pinus sylvestris) is prevalent on sandy soil (occupying ca 34.5% of the forested area).The fragments of secondary forest are dominated by birch (Betula pubescens, 18.4%) and aspen (Populus tremula, 5.0%).In mature forest stands, birch and aspen combined comprise 5.0-18.4% of the stand, whereas in old-growth forests they represent 3.4-6.9%.

Methods
Study area.The field material was collected during the vegetative growth period of forest plants in 2006-2012, 2014 and 2015 using radial routes (Tolmachev 1974, Shmidt 1984).The radial routes arranged with wind rose have been initiated in 16 directions from each locality within the study area (Fig. 2).All these routes ended on reaching a shoreline.The living and dead standing trees, fallen logs, stumps, wood debris, and forest litter were observed.In total, 3500 trees were included in this study.Individual collection sites are shown in Table 1 (Fig. 2).
Data collection.The material was collected during 9 field expeditions, that visited 17 collection sites, with a set of radial routes made at each site.In total, more than 2500 specimens were collected and identified.Most of the species are documented with herbarium materials deposited at the herbaria of the N. Laverov Federal Center for Integrated Arctic Research (AR) and the Karelian Research Center of the Russian Academy of Sciences (PTZ).
A laboratory study of basidiomata was carried out as described by Gilbertson and Ryvarden (1986).Freehand sections and squash mounts were examined in 5% KOH,

Results
An annotated checklist of aphyllophoroid fungi contains the data on the location of the finding and substrate of the species, the herbarium documentation, and a forest type where the fungus was recorded.Widely distributed species are listed basing on the field reports.The Roman numbers indicate key localities of the area as described above (Fig. 2).The frequency of occurrence is given as follows: very scarce (1 or 2 occurrences), scarce (3-5 occurrences), rather common (≥ 6 occurrences).The generic concepts are accepted according to CABI Bioscience Databases (Index Fungorum 2016).The species new for Arkhangelsk Region of Russia are marked with 2 asterisks, whereas the species new for Solovetsky Archipelago are labeled with only 1 asterisk.Species found only in anthropogenic sites of the archipelago are marked by a dagger ( †).

Discussion
The majority of species (82.5%) are saprotrophs inhabiting dead and fallen logs of trees and shrubs.The forest litter and soil were inhabited by 33 species and 16 species of saprotrophic species were found on dead basidiocarps.One species (Typhula erythropus) was recorded growing on fallen leaves.

Table 1 .
Numbers, names, and geographic coordinates of the localities in this study.