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Monograph
A survey of Hebeloma (Hymenogastraceae) in Greenland
expand article infoUrsula Eberhardt, Henry J. Beker§|, Torbjørn Borgen, Henning Knudsen#, Nicole Schütz, Steen A. Elborne¤
‡ Staatliches Museum für Naturkunde Stuttgart, Stuttgart, Germany
§ University of London, London, United Kingdom
| Plantentuin Meise, Meise, Belgium
¶ Unaffiliated, Silkeborg, Denmark
# Unaffiliated, Frederiksberg, Denmark
¤ Unaffiliated, Allerød, Denmark
Open Access

Abstract

This is the first study exclusively dedicated to the study of Hebeloma in Greenland. It is based on almost 400 collections, the great majority of which were collected by three of the co-authors over a period of 40 years and were lodged in the fungarium of the Natural History Museum in Copenhagen. The material was identified using molecular and morphological methods. In total, 28 species were recognized, 27 belonging to three sections, H. sects Hebeloma, Denudata and Velutipes. One species sampled was new to science and is here described as H. arcticum. For all species, a description, a distribution map within Greenland and macro and microphotographs are presented. A key is provided for the 28 species. The distribution of species within Greenland is discussed. The findings are placed in the context of studies of arctic and alpine Hebeloma from other parts of the world where comparable data exist. Notably, H. grandisporum, H. louiseae and H. islandicum, previously only known from Romania, Svalbard, Iceland or Norway, respectively, have been found in Greenland. The latter is also the only species encountered that does not belong to any of the above sections. Hebeloma excedens and H. colvinii – for the latter we here publish the first modern description – are to date only known from continental North America and now Greenland.

Keywords

Arctic distribution, High Arctic, Low Arctic, mycorrhizal hosts, new species, pruned median joining networks

Introduction

Hebeloma are notoriously difficult to identify to species. The genus is very common in arctic habitats and plays an important role as a mycorrhizal symbiont in arctic scrubland for plants like Salix, Betula and Dryas and thus for the turnover of nutrients in these harsh environments. In spite of their frequency and abundance in arctic areas, the alpha taxonomy of the genus was confused until the work of Beker and colleagues (Eberhardt et al. 2015a, b, 2016; Beker et al. 2016; Grilli et al. 2016) who described a number of new species from Europe, including the arctic and alpine regions of Europe, and reappraised the delimitation of known taxa.

Here we provide a review of Hebeloma spp. collected in Greenland and verified by molecular and morphological analysis. These encompass 378 of the 405 collection from Greenland that were digitized in the fungarium C of the Natural History Museum in Copenhagen, and represent 28 species. The great majority of this material was collected by three of the authors (T.B., S.A.E. and H.K.K.) over a period of 40 years in preparation for a forthcoming “Funga Arctica & Alpina” of basidiomycetes. The material presented here is a part of the 15.000 collections for the funga.

Each of the 28 species is presented with a morphological description, a photo of the macroscopic characters, photos of spores and cystidia as well as a distribution map of the collection sites in Greenland. Characters of each species are discussed and compared to related and similar species. Species ecology and distribution in Greenland and other regions (as appropriate) are discussed. Among these species is one species that is new to science and here described as H. arcticum. For another species, H. colvinii, originally described by Peck (1875; effectively published 1876), the first modern description is provided.

In spite of the amount of study that went into the genus, species identification, also by molecular data, remains challenging. Beker and co-workers used several loci (ITS, partial RPB2, partial Tef1a, partial MCM7, and the variable regions V6 and V9 of the mitochondrial genes). The sections mainly encountered in Greenland (H. sects. Denudata, Hebeloma and Velutipes) include a number of species that can only be distinguished by one of these loci, or by a combination of two loci or by combining molecular results and morphology. Also, a number of species are not monophyletic, even if all loci are concatenated. Although many species cannot be distinguished by ITS alone, the combination of ITS and morphology normally allows species identification (Beker et al. 2016).

Pruned median joining networks (Ayling and Brown 2008) are calculated to analyze the ITS results. Networks rather than trees are used to visualize DNA sequence variation when evolution has not been unidirectional. No assumptions are made with regard to which evolutionary mechanisms have been responsible for the observed variation. As in Cripps et al. (2019), it is not possible to unambiguously determine haplotypes from many sequences, i.e. when PCR was only successful in two fragments or when ambiguity in more than one single base pair position existed that was not accompanied by length variation. Therefore, we used as input for the network analysis what we refer to as “ITS variants”, for each collection, a consensus sequence of the ITS, whether or not intragenomic variation occurred. In the case of length variation, indels were treated as insertions.

Hebeloma in Greenland and similar arctic (and alpine) areas

Lange (Lange 1957) collected in Greenland in 1946 and recorded four species: Hebeloma mesophaeum, H. longicaudum, H. pusillum and H. strophosum. His material has not been revised for this study, which is solely based on sequenced samples. Of his four species, we confirmed the presence of H. mesophaeum, but the three other named species are open to interpretation. Hebeloma longicaudum (Pers.) P. Kumm. is considered to be impossible to typify in accordance with the diagnosis. Hebeloma pusillum J.E. Lange is a species forming small basidiomes and was described from Salix scrublands in Denmark. According to Beker et al. (2016) this species does not occur in arctic and subarctic areas of northern Europe; the symbiont is not dwarf Salix, but rather larger Salix in bogs and fens, such as S. aurita L., S. atrocinerea Brot. and S. cinerea L. Hebeloma strophosum (Fr.) Sacc. is now (Beker et al. 2016) considered to be a synonym of H. mesophaeum.

Petersen (1977) also reported H. mesophaeum and H. pusillum, referring to Gulden and Lange (1971), and he added H. crustuliniforme, material, which is more likely to have represented H. alpinum or H. velutipes. Lamoure et al. (1982) reported H. kuehneri (= H. nigellum) from Disko Island, from where we have later also recorded it.

Watling (1977) reported H. marginatulum and H. versipelle, noting that the latter was probably included in Lange’s (1957) concept of H. mesophaeum. According to Beker et al. (2016), H. versipelle is probably synonymous with H. mesophaeum, although synonymy with H. dunense cannot be excluded. Watling (1983) reported H. aff. leucosarx, H. marginatulum and H. mesophaeum, revising collections from A. Erskine (NE Greenland, in the surroundings of Mestersvig airstrip) and A. Fox (Eqalummiut Nunaat). All of these species are here confirmed for Greenland, although H. populinum Romagn., mentioned by Watling as similar to his H. aff. leucosarx, is not and in fact is not known to occur north of the southern part of the British Isles. According to modern taxonomy, H. populinum is a member of H. sect. Denudata, and not a close relative of H. leucosarx which is a member of H. sect. Velutipes (Beker et al. 2016).

When Vesterholt (1989) revised the veiled species of Hebeloma in the Nordic countries, he included material from Greenland of H. helodes, H. leucosarx and H. marginatulum. Later Vesterholt (2005) added H. alpinum, H. nigellum (as H. kuehneri), H. subconcolor and H. vaccinum in his book “The Genus Hebeloma” and finally he added H. dunense (as H. collariatum). Two species reported in Borgen et al. (2006), H. sinapizans and H. monticola, are not among the material in this survey, and at least H. sinapizans is unlikely to be found. The collections ascribed to H. sinapizans may have represented H. alpinum or H. geminatum, the former in at least one case. Some, at least, of the collections of H. monticola, are now known to represent either H. nigellum or H. oreophilum, although it is likely that H. monticola may indeed be present in Greenland, particularly in the southern, subarctic areas.

Given the problems with interpretation of Hebeloma species names, in particular from the pre-molecular era, and therefore the application of taxon names, we will not make further reference to these studies. A small number of studies of other alpine or arctic regions have been published which use names in the same manner as here. Recently, Eberhardt et al. (2015a) described new species of Hebeloma from the alpine belt of the Carpathians. Beker et al. (2016) dedicated part of a chapter to alpine/arctic Hebeloma, identifying 17 species as ‘specialists’ and 8 species as ‘opportunists’ in these habitats in Europe. Beker et al. (2018) reviewed Hebeloma in Svalbard and recorded 17 species, of which five were only known from Svalbard. Cripps et al. (2019) described Hebeloma from the alpine Rocky Mountains in USA and found 16 species, of which one was subalpine and connected to conifers. Most recently, Grilli et al. (2020) presented seven species of Hebeloma from the Alps. This does not mean that, for example, we consider reports of H. alpinum, H. marginatulum or H. mesophaeum from various parts of the Russian Arctic or Alaska (Nezdoiminogo 1994; Miller 1998; Karatygin et al. 1999; Shiryaev et al. 2018; Gorbunova 2019) as unlikely, but we prefer to be consistent in referring only to material we have been able to validate.

Bioclimatic zones and the collecting sites in Greenland

Greenland is an island, which for the greater part is covered by an ice cap, the Inland Ice. The island is biogeographically divided into four parts. South Greenland is the area south of 62.20°N. West Greenland is the area from 62.20°N to 74°N on the western side of the island. North Greenland is the area north of 74°N, and East Greenland the area on the eastern side between 74°N and 62.20°N.

The length of the island is ca. 2000 km, but only two bioclimatic zones are present, the Subarctic zone and the Arctic (or Polar) zone (Fredskild 1996). The Subarctic zone has a climate where the warmest month has an average temperature above 10 °C. This area is very small and restricted to the bottom of some of the fjords in South Greenland around Narsarsuaq. The outer part of the fjords is moist and cool, but in the protected inner parts, the temperature may rise during the summer to reach an average 10 °C for July. Botanically, this Subarctic zone is defined by the coincident occurrence of the two plants, Sagina nodosa and Eleocharis quinqueflora. The interest for Hebeloma lies in the occurrence of woodland with large specimens of Betula pubescens var. pumila (L.) Govaerts in a few valleys (Feilberg 1984), associated with a number of subarctic fungi (Elborne and Knudsen 1990). All other parts of Greenland are arctic. This is separated into the Low Arctic zone and the High Arctic zone. This separation (Fig. 1A) is important for the distribution of many organisms including fungi. The dividing line runs from the central part of Disko Island in the West across the Inland Ice to Blosseville Coast in the East, i.e. approximately along 70°N. The High Arctic zone has four months with an average temperature above 0 °C, whereas the Low Arctic zone has six months above 0 °C.

Figure 1. 

A Demarcation of Low and High Arctic, and B limits of North, East, West and South Greenland and location important collection sites.

Collection sites are not distributed uniformly throughout Greenland since many areas are difficult to access. Collecting activities were concentrated on a few localities scattered over the accessible part of Greenland (Fig. 1B), taking into account the variation in the climate, soil and vegetation that defines the funga on this big island. A reflection of this is seen in the maps, where dots are always absent from some parts of Greenland, due to inaccessibility. This is especially true for NW Greenland (Melville Bay), where the Inland Ice comes out to the sea, leaving little opportunity for fungal life. The other area where records are generally missing is the southern half of the east coast, i.e. from the southernmost point in Greenland and up to Jameson Land on the East side. This is generally inaccessible, or extremely difficult to access, but a few collections were made by T.B. at Tasiilaq/Ammassalik. Finally, northernmost Greenland is an arctic desert, where the snowfall is generally too low to support fungi. Thus, our five main localities are Narsarsuaq, Paamiut, Kangerlussuaq, Zackenberg and Jameson Land.

Narsarsuaq at 60°N

A well-investigated area housing one of the two airports, which receives regular air traffic from Copenhagen. Generally a Low Arctic area, but at the bottom of some of the fjords the climate is Subarctic, and scrubland of Betula pubescens var. pumila occurs. The trunks attain heights up to 7–8 m and diameters to ca. 30 cm. Apart from these scrublands, occurring in a very restricted area, Betula glandulosa Michaux is widespread and common in the area. Salix glauca L. is ubiquitous, forming 1–3 m high shrubs, S. arctophila Cockerell and S. herbacea L. are common, while S. uva-ursi Pursh is rare and scattered. Dryas integrifolia M. Vahl is scattered. The soil is mixed, but generally rich in the valleys.

Paamiut at 62°N

This is the best studied area in Greenland for fungi as T.B. lived here for 20 years. The bedrock is acidic gneiss, in places with weathered basaltic dykes, and areas with less acid, syanitic “rotten” mountains. The climate is Low Arctic and hyper oceanic along the coast with heaths and snowbeds with Salix herbacea. Inland, Betula glandulosa heaths and copses of Salix glauca dominate. In addition to these widespread and common types of vegetation, a few scrubland areas of Alnus alnobetula subsp. crispa (Aiton) Raus. as well as Dryas integrifolia occur. Betula pubescens Erh. also grow here rarely, close to its northern limit.

Kangerlussuaq at 67°N

A well-studied area for the same reason as Narsarsuaq, in that the presence of an airport implies regular air traffic from Copenhagen. The area is Low Arctic and the bottom of the Kangerlussuaq Fjord (formerly Søndre Strømfjord) is the most continental area in Greenland, warm and dry in the summertime and even with salt lakes. The vegetation consists of low shrubs of Betula nana L., Salix glauca, S. herbacea and S. arctophila. Dryas integrifolia is common. The soil along the river and fjord is generally very rich due to loess coming from the Inland Ice with the rivers and with the wind, but the surrounding bedrock is acidic gneiss.

Zackenberg at 74.5°N

This area has been studied over the last 25 years, since the establishment of a field station in this High Arctic part of the Greenland National Park. Fungi were studied during two seasons by T.B. The shrub vegetation is Betula nana, Salix arctica Pall., S. herbacea, Dryas integrifolia and D. octopetala ssp. punctata (Juz.) Hult. The bedrock is gneissic or sedimental, mixed on the plains.

Constable Pynt, Jameson Land at 70.8°N

The area is situated on the border between Low Arctic and High Arctic and is accessible during summertime from Iceland. We studied the area in 1989 and in 2017. The bedrock is calcareous and the soil is generally nutrient rich. The vegetation is shrubs of Betula nana, Salix arctica, S. glauca and Dryas octopetala L.

Materials and methods

Collections

This study is based on 378 collections of Hebeloma from Greenland, which yielded (at least) ITS sequence data. Collections, which did not produce a sequence, are not considered further in this paper.

T.B., S.A.E. and H.K.K. collected 325 of the included collections over a period of 40 years. The remaining 56 collections were collected by Erik Rald (21), David Boertmann (9), Esteri Ohenoja (5, Herb. OULU), H.K.J.B. (4, HJB), Bent Fredskild (4), Egon Horak (2, Herb. ZT), Christian Bay (2), T.T. Elkington (2), Børge Lauritsen (2), Thomas Læssøe (2), Jens H. Petersen (1), Kuulo Kalamees (1) and Birger Knudsen (1). Many collections are provided with notes and photos. Unless otherwise mentioned, all material is kept at the Fungarium at the Natural History Museum of Denmark (C) in Copenhagen.

Photos were taken in the field with a camera or with an iphone, and T.B. also often took a laboratory photo of the fresh specimens. Collections were dried on an electrical heater whenever possible. In uninhabited areas without access to electricity, a system was used with three sieves fastened on aluminium “legs” and surrounded by a cylinder of wax cloth, creating a closed column. The “legs” were fastened to the ground, and beneath the sieves, a small kerosene lamp was placed to dry the material overnight.

Molecular analyses

Dried collections were used as the source for genomic DNA. DNA extraction followed Cripps et al. (2019), with more recent material (i.e. younger than 20 years) omitting the pre-lysis incubation with lytic enzyme and omitting the lysis step overnight at 37 °C. Also, the time for DNA precipitation was shortened to 15–60 min.

PCR followed Cripps et al. (2019), but using the standard primer combination of ITS1F and ITS4 (White et al. 1990; Gardes and Bruns 1993) for more recent material. Partial RPB2 PCR products (encoding the second largest subunit of RNA polymerase II; forward primer bRPB2-6f ‘TGG GGY ATG GTN TGY CCY GC’, Matheny 2005; and reverse fRPB2-7cr ‘CCC ATR GCT TGY TTR CCC AT’, Liu et al. 1999) were generated in 25 µl PCR reactions, using hotstart Taq polymerase, i.e. 1.25u Bioline (London, UK) MyTaq HS DNA Polymerase, 5 µl of 5× buffer, 20 pmol of each primer and 10% (2.5 µl) of 1:25 diluted DNA extract. PCRs were run with 5 min 95 °C, 40 cycles of 1 min 95 °C, 1 min 50 °C, 2 min 72 °C, and a final elongation of 5 min at 72 °C. The PCR cocktail for partial Tef1a, other than primers (translation elongation factor 1-α; forward primer elo31m ‘TTC ATC AAG AAC ATG ATC AC’ and reverse elo33R_A ‘GAC GTT GAA ACC RAC RTT GTC’, modified from Stielow et al. 2015) and Taq (MyTaq DNA polymerase, Bioline) was the same as for RPB2; PCRs were run as follows: 5 min 95 °C, 10 cycles of 45 sec 95 °C, 45 sec 58 °C, 1 min 72 °C, 35 cycles of 45 sec 95 °C, 45 sec 48 °C, 1 min 72 °C, and a final elongation of 5 min at 72 °C.

Sequencing was done by LGC Genomics (Berlin, Germany), using the PCR primers as sequencing primers. Sequences were edited using Sequencher (vs. 4.2 or 4.8). Newly generated sequences were submitted to GenBank (accession nos MW357874MW357877, MW357892MW357897, MW445544MW445902, MW452577MW452595, MW465762, MW465838 and MW465839). Other sequences used were previously published by Eberhardt et al. (2009, 2015a, b, 2016, 2018), Beker et al. (2010, 2013, 2016), Schoch et al. (2012), Grilli et al. (2016) and Cripps et al. 2019). Table 1 lists the GenBank accession numbers for the Greenland material treated in this paper.

Table 1.

Hebeloma database references (see Beker et al. 2016), voucher information and Genbank accession numbers of Greenland collections considered in this study. For details, see Materials and Methods. Vouchers are from the fungal collection of the Herbarium of the University of Copenhagen (C), of the University of Oulu (OULU) or the collection of E. Horak at the herbarium of the Eidgenössische Technische Hochschule Zürich (ZT) or from the private collection of H.K.J. Beker.

Hebeloma Database reference Voucher Other Number Genbank acc. no. ITS
Hebeloma alpinicola
HJB15784 C-F-119805 TB99.238 MW445632
HJB16321 C-F-5081 TB85.071 MW445633
HJB16322 C-F-5082 TB85.099 MW445634
HJB16580 C-F-103554 TB81.111 MW445635
HJB16585 C-F-103532 TB85.218 MW445636
HJB16605 C-F-103516 TB00.049 MW445637
HJB16664 C-F-103534 TB84.063 MW445638
HJB16688 C-F-103559 TB84.028 MW445639
HJB17503 C-F-101623 TB08.039 MW445640
HJB17505 C-F-101621 TB08.037 MW445641
HJB17669 C-F-108401 HK16.165 MW445642
HJB18928 C-F-111109 HK18.010 MW445643
HJB18935 C-F-111116 HK18.322 MW445644
Hebeloma alpinum
HJB11887 C-F-103458 TB86.115 MW445593
HJB12191 C-F-119742 TB99.027 MW445594
HJB12194 C-F-119744 TB99.023 KM390632, KM390633
HJB12204 C-F-104294 TB99.199 KM390685
HJB15711 C-F-119763 TB06.034 MW445544
HJB15714 C-F-119766 TB06.137 MW445545
HJB15785 C-F-119806 TB99.115 MW445548
HJB15786 C-F-119807 TB99.159 MW445549
HJB15787 C-F-119808 TB99.283 MW445550
HJB16276 C-F-101230 TB86.153 MW445551
HJB16581 C-F-103537 TB84.148 MW445552
HJB16591 C-F-103507 TB97.153a MW445554
HJB16594 C-F-103506 TB97.152 MW445555
HJB16631 C-F-103565 TB86.141 MW445559
HJB16638 C-F-103503 TB95.004 MW445560
HJB17442 C-F-106779 TB17C.089 MW445564
HJB17445 C-F-106775 TB17C.053 MW445565
HJB17455 C-F-106784 TB17C.134 MW445566
HJB17458 C-F-105185 HK17.278 MW445567
HJB17459 C-F-104889 HK17.001 MW445568
HJB17461 C-F-105024 HK17.123 MW445569
HJB17467 C-F-104893 HK17.005 MW445570
HJB17470 C-F-105050 HK17.148 MW445571
HJB17475 C-F-104938 HK17.049 MW445595
HJB17476 C-F-104912 HK17.023 MW445572
HJB17477 C-F-104894 HK17.006 MW445573
HJB17482 C-F-104895 HK17.007 MW445575
HJB17486 C-F-104943 HK17.054 MW445576
HJB17491 C-F-106759 SAE-2017.014 MW445577
HJB17498 C-F-106758 SAE-2017.008 MW445579
HJB17509 C-F-106757 SAE-2017.006 MW445581
HJB17510 C-F-106766 SAE-2017.188 MW445582
HJB17663 C-F-104951 HK17.062 MW445586
HJB17687 C-F-5180 BF 90 loc. 6 MW445584
HJB18934 C-F-111115 HK18.308 MW445589
HJB18938 C-F-111119 HK18.390D MW445591
Hebeloma arcticum
HJB16618 C-F-103571 TB86.277A MW445558
HJB16673 C-F-103555 TB90.083 MW445561
HJB16676 C-F-103483 TB90.071 MW445562
HJB16687 C-F-103584 TB16.095 MW445563
HJB17506 C-F-106751 TB08.153 MW445580
HJB17662 C-F-108472 SAE-2000.021-GR MW445585
HJB17673 C-F-104149 HK16.119 MW445587
HJB17680 C-F-104080 HK16.044 MW445588
Hebeloma aurantioumbrinum
HJB11884 C-F-119737 TB84.112 MW445897
HJB11885 C-F-2309 HK89.366 MW445896
HJB12189 C-F-119741 TB06.091 MW445899
HJB12205 C-F-119751 TB99.044 MW445898
HJB15716 C-F-119768 TB06.150 MW445858
HJB15719 C-F-119771 TB06.259 MW445859
HJB15740 C-F-119784 DB 85-17 MW357875
HJB15741 C-F-119785 DB 85-28 MW357892
HJB15742 C-F-103459 TB85.239 MW445861
HJB15751 C-F-2327 SAE-89.121 MW445863
HJB15752 C-F-2424 SAE-89.430 MW445864
HJB15753 C-F-119787 DB GR88-22 MW445865
HJB15756 C-F-1461 SAE-88.149-GR MW445866
HJB15757 C-F-119788 HK87.218 MW445867
HJB15758 C-F-119789 SAE-87.113-GR MW445868
HJB15759 C-F-119790 HK87.004 MW445869
HJB15766 C-F-103462 TB84.135 MW445870
HJB15767 C-F-119792 TB84.150 MW445871
HJB15771 C-F-3637 MW445872
HJB15775 C-F-119797 MW445874
HJB16578 C-F-103461 TB84.132 MW445875
HJB16624 C-F-103502 TB93.070 MW445876
HJB16633 C-F-103570 TB86.251 MW445878
HJB16671 C-F-103484 TB90.072 MW445879
HJB16672 C-F-103546 TB90.039 MW445880
HJB16678 C-F-103481 TB90.041 MW445881
HJB16680 C-F-103545 TB90.029 MW445882
HJB16681 C-F-103482 TB90.057 MW445883
HJB16683 C-F-103547 TB90.012 MW445884
HJB16684 C-F-103548 TB90.011 MW445885
HJB16686 C-F-103485 TB90.133 MW445886
HJB16697 C-F-103526 TB85.217 MW445894
HJB17060 C-F-6992 MW445888
HJB17061 C-F-6993 MW445889
HJB17078 C-F-104315 ER93.262 MW445890
HJB17083 C-F-104321 ER93.091 MW445891
HJB17521 C-F-106745 SAE-2016.146 MW445892
HJB17674 C-F-104118 HK16.089 MW445893
HJB18933 C-F-111114 HK18.296 MW445895
HJB19596 C-F-103570 TB86.277B MW445900
Hebeloma clavulipes
HJB12316 C-F-119760 TB 90.100 MW357874
Hebeloma colvinii
HJB16630 C-F-103585 TB16.075 MW445745
HJB17502 C-F-106756 TB02.166 MW445746
HJB17684 C-F-104038 HK16.008 MW445747
HJB17685 C-F-104035 HK16.005 MW445748
HJB19653 C-F-107346 SAE-2016.188-GR MW445749
Hebeloma dunense
HJB12196 C-F-119746 TB99.114 MW445645
HJB12198 C-F-119748 TB99.411 MW445646
HJB12206 C-F-119752 TB99.219 MW445647
HJB15722 C-F-119774 TB06.159 MW445648
HJB15724 C-F-119776 TB06.263 MW445649
HJB16324 C-F-5087 TB86.159 MW445650
HJB16584 C-F-103530 TB85.200 MW445651
HJB16590 C-F-103486 TB91.045 MW445652
HJB16595 C-F-103536 TB84.114 MW445653
HJB16635 C-F-103563 TB86.177 MW445654
HJB16639 C-F-103589 TB85.183 MW445655
HJB16650 C-F-103527 TB85.186 MW445656
HJB16651 C-F-103535 TB84.090 MW445657
HJB17057 C-F-2561 JHP 89.259 MW445658
HJB17058 C-F-4216 MW445659
HJB17062 C-F-7017 MW445660
HJB17064 C-F-8231 HK15.078 MW445661
HJB17066 C-F-104293 TB16.076 MW445662
HJB17444 C-F-106782 TB17C.118 MW445663
HJB17449 C-F-106771 TB17C.010 MW445664
HJB17450 C-F-106770 TB17C.006 MW445665
HJB17452 C-F-106780 TB17C.094 MW445666
HJB17453 C-F-106773 TB17C.037 MW445667
HJB17456 C-F-106772 TB17C.030 MW445668
HJB17462 C-F-104959 HK17.070 MW445669
HJB17463 C-F-104932 HK17.043 MW445670
HJB17465 C-F-105171 HK17.265B MW445671
HJB17466 C-F-105189 HK17.282 MW445672
HJB17471 C-F-104984 HK17.088 MW445673
HJB17474 C-F-104934 HK17.045 MW445674
HJB17481 C-F-105049 HK17.147 MW445675
HJB17483 C-F-105170 HK17.265A MW445676
HJB17484 C-F-105108 HK17.203 MW445677
HJB17485 C-F-104941 HK17.052 MW445678
HJB17487 C-F-105028 HK17.127 MW445679
HJB17488 C-F-104945 HK17.056 MW445680
HJB17497 C-F-106765 SAE-2017.186 MW445681
HJB17507 C-F-106761 SAE-2017.103 MW445682
HJB17508 C-F-106769 SAE-2017.219 MW445683
HJB17678 C-F-104045 HK16.015 MW445684
HJB17688 C-F-6994 MW445685
HJB19155 C-F-7881 HK00-032 MW445686
Hebeloma excedens
HJB13537 OULU F051033 EO19.8.00 MW445687
HJB16320 C-F-5073 TB85.238 MW445688
HJB16604 C-F-103517 TB00.086 MW445689
Hebeloma fuscatum
HJB15739 C-F-119783 DB 85-21 MW445760
HJB17454 C-F-106783 TB17C.129 MW445787
HJB17473 C-F-104987 HK17.091 MW445789
HJB17478 C-F-104897 HK17.009A MW445790
HJB17494 C-F-106768 SAE-2017.215 MW445791
HJB17517 C-F-106737 SAE-2016.072 MW445797
HJB18945 C-F-112530 TB18.243 MW445819
HJB18946 C-F-115623 DB 12.047 MW445820
Hebeloma geminatum
HJB16588 C-F-103508 TB97.154a MW445553
HJB16596 C-F-103514 TB00.065 MW445556
HJB18936 C-F-111117 HK18.379B MW445590
Hebeloma grandisporum
HJB17067 C-F-104295 TB99.376 MW445784
HJB17460 C-F-104997 HK17.101 MW445788
Hebeloma helodes
HJB15747 C-F-103460 TB85.072 MW445862
HJB15748 C-F-103476 TB85.090 MW357894
HJB15780 C-F-4003 TB88.114 MW445873
HJB16627 C-F-103525 TB85.065 MW445877
HJB17044 C-F-104317 ER93.153 MW445887
Hebeloma hiemale
HJB12193 C-F-119743 TB06.067 GQ869517
HJB12195 C-F-119745 TB99.258 GQ869515
HJB12200 C-F-104296 TB99.146 GQ869524
HJB12202 C-F-119777, TB06.081 GQ869518
HJB12210 C-F-119756 TB99.118 GQ869516
HJB12544 Coll. E. Horak at ZT 8901 GQ869527
HJB13538 OULU F050202 EO12.8.00 MW445631
HJB15712 C-F-119764 TB06.250 MW445596
HJB15713 C-F-119765 TB06.120 MW445597
HJB15715 C-F-119767 TB06.128 MW445598
HJB15717 C-F-119769 TB06.061 MW445599
HJB15718 C-F-119770 TB06.033 MW445600
HJB15736 C-F-103465 TB91.136 MW445601
HJB15737 C-F-119782 TB91.112 MW445602
HJB15743 C-F-103466 TB85.182 MW445603
HJB15746 C-F-119786 TB85.250 MW357893
HJB15770 C-F-119794 TL 84.608 MW357895
HJB15781 C-F-119802 TB99.280 MW445604
HJB15782 C-F-119803 TB99.304 MW445605
HJB15788 C-F-119809 TB99.160 MW445606
HJB16600 C-F-103515 TB00.069 MW445607
HJB16616 C-F-103497 TB93.183 MW445608
HJB16619 C-F-103499 TB93.210 MW445609
HJB16621 C-F-103498 TB93.187 MW445610
HJB16622 C-F-103500 TB93.155 MW445611
HJB16628 C-F-103552 TB81.112 MW445612
HJB16636 C-F-103496 TB93.159 MW445613
HJB16659 C-F-103543 TB90.032 MW445614
HJB16666 C-F-103540 TB90.087 MW445615
HJB16667 C-F-103549 TB90.084 MW445616
HJB16674 C-F-103544 TB90.019 MW445617
HJB16675 C-F-103568 TB86.203 MW445618
HJB16685 C-F-103550 TB90.104a MW445619
HJB16692 C-F-103504 TB95.114 MW445620
HJB17042 C-F-104550 ER93.330 MW445621
HJB17043 C-F-104292 TB98.201 MW445622
HJB17045 C-F-104551 ER93.302 MW445623
HJB17080 C-F-104318 ER93.152 MW445624
HJB17443 C-F-106776 TB17C.072 MW445625
HJB17446 C-F-106777 TB17C.078 MW445626
HJB17501 C-F-106752 TB08.157 MW445627
HJB18931 C-F-111112 HK18.269 MW445628
HJB18941 C-F-112771 SAE-2018.225-GR MW445629
HJB18942 C-F-112904 SAE-2018.357-GR MW445630
Hebeloma hygrophilum
HJB16647 C-F-103511 TB98.234 MW357897
HJB17041 C-F-104549 ER93.425 MW445783
HJB17516 C-F-106736 SAE-2016.022 MW445796
HJB17520 C-F-106735 SAE-2016.005 MW445799
HJB17522 C-F-106741 SAE-2016.105 MW445800
HJB17523 C-F-106746 SAE-2016.168 MW445801
HJB17524 C-F-106742 SAE-2016.116 MW445802
HJB17661 C-F-108600 SAE-2000.148-GR MW445803
HJB17667 C-F-108446 HK16.195 MW445804
HJB17681 C-F-104093 HK16.064 MW445811
HJB18937 C-F-111118 HK18.390A MW445815
HJB18943 C-F-115622 SAE-2018.429-GR MW445817
HJB18944 C-F-112528 TB18.236 MW445818
HJB19151 C-F-105494 ER93.519 MW445813
HJB19710 C-F-137115 TB19.052 MW445821
Hebeloma ingratum
HJB10797 C-F-119732 HK87.262 KT217437
HJB13546 OULU F050503 EO18.8.00.36 MW445837
HJB16620 C-F-103501 TB93.205 MW445826
HJB17513 C-F-106748 SAE-2016.208 MW445831
Hebeloma islandicum
HJB16632 C-F-103573 TB86.291 MW445901
Hebeloma leucosarx
HJB16656 C-F-103513 TB98.119 MW445844
HJB16658 C-F-103551 TB81.211 MW445845
Hebeloma louiseae
HJB16602 C-F-103518 TB00.061 MW445557
HJB17479 C-F-105029 HK17.128 MW445574
HJB17493 C-F-106763 SAE-2017.125A MW445578
HJB17519 C-F-106747 SAE-2016.197 MW445583
HJB19601 C-F-106763 SAE-2017.125B MW445592
Hebeloma marginatulum
HJB10730 Priv. coll. HJB10730 MW445690
HJB10732 Priv. coll. HJB10732 MW445691
HJB10739 Priv. coll. HJB10739 MW445692
HJB10742 Priv. coll. HJB10742 MW445693
HJB12197 C-F-119747 TB06.090 MW445694
HJB15723 C-F-119775 TB06.158 MW445695
HJB15727 C-F-119779 TB06.090 MW445696
HJB15762 C-F-103467 TB86.247 MW445697
HJB16323 C-F-5085 TB85.036 MW445698
HJB16327 C-F-5090 TB86.072 MW445699
HJB16612 C-F-103489 TB91.198 MW445700
HJB16623 C-F-103495 TB93.139 MW445701
HJB16646 C-F-103566 TB86.119 MW445702
HJB16652 C-F-103493 TB92.027 MW445703
HJB16654 C-F-103492 TB92.028 MW445704
HJB16663 C-F-103553 TB81.109 MW445705
HJB16665 C-F-103538 TB84.151 MW445706
HJB16691 C-F-103505 TB95.068 MW445707
HJB17049 C-F-104552 ER93.320 MW445708
HJB17050 C-F-104300 TB86.299 MW445709
HJB17051 C-F-104306 ER92.181 MW445710
HJB17052 C-F-104314 ER93.181 MW445711
HJB17059 C-F-6922 TB86.060 MW445712
HJB17070 C-F-104304 ER92.109 MW445713
HJB17071 C-F-104305 ER92.180 MW445714
HJB17077 C-F-104312 ER93.111 MW445715
HJB17081 C-F-104319 ER93.021 MW445716
HJB17086 C-F-104554 ER93.589 MW445717
HJB17457 C-F-106421 ER93.112 MW445718
HJB17489 C-F-105051 HK17.149 MW445719
HJB17490 C-F-106738 SAE-2016.085 MW445720
HJB17499 C-F-106749 TB08.126 MW445721
HJB17500 C-F-106753 TB09K017 MW445722
HJB17525 C-F-101622 TB08.035 MW445723
HJB17526 C-F-106750 TB08.146 MW445724
HJB17658 C-F-108419 HK16.181 MW445725
HJB17666 C-F-108418 HK16.180 MW445726
HJB17677 C-F-104164 HK16.134 MW445727
HJB17683 C-F-104111 HK16.082 MW445728
HJB17686 C-F-5113 BF 90 loc. 5 MW445729
HJB17689 C-F-5147 BF 90 loc. 8 MW445730
HJB18932 C-F-111113 HK18.288 MW445731
Hebeloma mesophaeum
HJB12213 C-F-104297 TB99.264 MW445735
HJB12313 C-F-119759 TB90.040 MW465762
HJB13560 OULU F050224 EO12.8.00.1 MW445736
HJB16348 C-F-76757 TB90.086 MW445732
HJB16598 C-F-103521 TB00.093 MW445737
HJB16601 C-F-103522 TB00.094 MW445738
HJB16603 C-F-103520 TB00.091 MW445739
HJB16629 C-F-103578 TB16.040G MW445740
HJB17068 C-F-104301 TB16.038 MW445741
HJB17464 C-F-104908 HK17.020 MW445733
HJB19682 C-F-137116 TB00.088 MW445734
Hebeloma minus
HJB15745 C-F-104302 TB86.085 MW445546
HJB15769 C-F-119793 TL 84.041 MW445547
Hebeloma nigellum
HJB10957 C-F-119734 DB GR83-80 MW445750
HJB11874 C-F-103468 TB84.183 MW445752
HJB11888 C-F-119739 TB86.052 MW445751
HJB12545 Coll. E. Horak at ZT 9139 MW445756
HJB13559 OULU F050653 EO19.8.00.20 MW445758
HJB15761 C-F-119791 TB86.065 MW445761
HJB16592 C-F-103577 TB16.035G MW445764
HJB16606 C-F-103490 TB91.080 MW445766
HJB16634 C-F-103572 TB86.276 MW445769
HJB16657 C-F-103529 TB85.249 MW445773
HJB16670 C-F-103479 TB90.035 MW445776
HJB16677 C-F-103541 TB90.073 MW445777
HJB16679 C-F-103542 TB90.056 MW445778
HJB16694 C-F-103583 TB16.086G MW445781
HJB16696 C-F-103580 TB16.060G MW445782
HJB17518 C-F-106743 SAE-2016.131 MW445798
HJB17670 C-F-108402 HK16.165A MW445805
HJB17675 C-F-104140 HK16.110 MW445808
HJB17676 C-F-104163 HK16.133 MW445809
HJB17679 C-F-104063 HK16.033 MW445810
HJB18929 C-F-111110 HK18.199 MW445814
Hebeloma oreophilum
HJB11889 C-F-119740 TB85.180 MW445755
HJB12199 C-F-119772 TB06.225 MW445757
HJB12212 C-F-119758 TB99.374 MW445753
HJB15721 C-F-119773 TB06.098 MW445759
HJB15768 C-F-104298 TB84.215 MW445762
HJB16589 C-F-103539 TB84.184 MW445763
HJB16599 C-F-103576 TB16.017G MW445765
HJB16611 C-F-103487 TB91.233 MW445767
HJB16613 C-F-103588 TB86.292 MW445768
HJB16644 C-F-103510 TB98.120 MW445770
HJB16645 C-F-103509 TB98.073 MW445771
HJB16648 C-F-103590 TB85.061 MW445772
HJB16668 C-F-103472 TB83.035 MW445774
HJB16669 C-F-103558 TB90.010 MW445775
HJB16682 C-F-103480 TB90.036 MW445779
HJB17515 C-F-106744 SAE-2016.134 MW445795
HJB17672 C-F-104120 HK16.091 MW445807
HJB18939 C-F-111120 HK18.401 MW445816
Hebeloma pubescens
HJB12203 C-F-119750 TB99.194 MW445742
HJB12207 C-F-119753 TB99.305 MW445743
HJB16326 C-F-5089 TB86.128 MW445744
Hebeloma spetsbergense
HJB10869 C-F-119733 SAE-1986.135-GR MW445822
HJB12211 C-F-119757 TB99.256 MW445754
HJB15763 C-F-103478 TB86.121 MW357896
HJB15779 C-F-119801 DB 83-62 MW357877
HJB16693 C-F-103579 TB16.056G MW445780
HJB17447 C-F-106781 TB17C.113 MW445785
HJB17448 C-F-106774 TB17C.050 MW445786
HJB17495 C-F-106764 SAE-2017.174 MW445792
HJB17496 C-F-106760 SAE-2017.043 MW445793
HJB17514 C-F-106740 SAE-2016.102 MW445794
HJB17671 C-F-108450 MW445806
HJB17682 C-F-104100 HK16.071 MW445812
Hebeloma subconcolor
HJB12413 C-F-119761 TB90.018 KT218391
HJB15750 C-F-2195 HK89.302 MW445840
HJB15760 C-F-4002 TB87.117 MW445841
HJB16579 C-F-103587 TB86.122 MW445902
HJB17055 C-F-104299 TB90.033 MW445848
HJB17056 C-F-104313 ER93.168 MW445849
HJB17065 C-F-8242 HK15.089 MW445847
HJB17512 C-F-106739 SAE-2016.090 MW445852
HJB18930 C-F-111111 HK18.232 MW445855
Hebeloma vaccinum
HJB12190 C-F-119780, TB06.246 KT217493
HJB12209 C-F-119755 TB99.109 KT217494
HJB15749 C-F-103477 TB85.045 MW357876
HJB15783 C-F-119804 TB99.008 MW445838
HJB17063 C-F-8222 HK15.069 MW445833
HJB17073 C-F-104308 ER92.038 MW445834
HJB17076 C-F-104311 ER92.323 MW445835
HJB17082 C-F-104320 ER93.022 MW445836
HJB17451 C-F-106778 TB17C.073 MW445827
HJB17469 C-F-104909 HK17.021 MW445828
HJB17472 C-F-104910 HK17.022A MW445829
HJB17492 C-F-106767 SAE-2017.194 MW445830
HJB17664 C-F-104911 HK17.022B MW445832
Hebeloma velutipes
HJB12201 C-F-119749 TB99.336 MW445857
HJB12208 C-F-119754 TB99.309 MW445856
HJB15730 C-F-103557 TB86.179 MW445839
HJB16597 C-F-103519 TB00.073 MW445842
HJB16655 C-F-103512 TB98.158 MW445843
HJB16689 C-F-103582 TB16.087G MW445846
HJB17468 C-F-105090 HK17.186 MW445850
HJB17511 C-F-106762 SAE-2017.110 MW445851
HJB17659 C-F-108492 SAE-2000.041-GR MW445853
HJB17660 C-F-108502 SAE-2000.051-GR MW445854

Sequences were aligned in Mafft v. 7 online (https://mafft.cbrc.jp/alignment/server/, Katoh et al. 2019), using the G-INS-i method for ITS sequences for networks and the E-INS-i for ITS, RPB2 and Tef1a data for the tree analysis.

Following Cripps et al. (2019), pruned quasi-median joining networks (Ayling and Brown 2008) were used to visualize the biological diversity of ITS sequences generated from Greenland collections. In the networks, observed sequence variants are shown as circles and the size of each circle gives some indication of the number of times the respective sequence variant has been retrieved. Two circles connected by an unsegmented line differ in 1 bp. So-called quasimedians, a kind of placeholder for unobserved sequence variants depicted as small squares, are placed between observed sequence variants that each differ from the quasi-median by 1 bp. The number of segments to a line represents the number of base pair changes between two sequence variants or a sequence variant and a quasi-median. A pruning mechanism is applied to reduce the complexity of the networks while depicting at least one shortest path between all pairs of sequence variants (Ayling and Brown 2008).

Only complete ITS sequences were considered. The Greenland sequences were incorporated in alignments previously published by Cripps et al. (2019). Hebeloma ingratum was not encountered by Cripps et al. (2019), but is present in the Greenland sample. Thus the H. cavipes/H. vaccinum dataset was extended by 10 randomly selected H. ingratum sequences from Europe. Because of the large number of sequences, and because there was no overlap between H. marginatulum and the other members of the species group around H. mesophaeum, H. marginatulum sequences were analyzed in a separate analysis. Hebeloma incarnatulum, a boreal species included by Cripps et al. (2019) in the H. sect. Velutipes network, was excluded from the analysis as it had no corresponding data in the Greenland sample. Alignments are published in TreeBase (Study ID TB2:S27569), where GenBank acc. numbers for all sequences used are given.

Networks were calculated in SplitsTree (version 4.15.1, Huson and Bryant 2006) with the default options other than activating the ‘scale nodes by taxa’ and ‘subdivide edges’ options. Nodes representing different classes of sequences (differentiated by species and origin, ‘Greenland’ versus ‘outside Greenland’) were replaced in Adobe Illustrator CS6 by pie charts of corresponding diameters, showing the relative numbers of sequences for each class.

For showing the phylogenetic placement of the newly described species H. arcticum, a tree analysis of members of H. subsect. Crustuliniformia was included, based on concatenated data of ITS, RPB2 and Tef1a. Table 2 lists the respective GenBank asscion numbers. Tree analyses were done locally in RAxML (Stamatakis 2014) using raxmlGUI v. 2.0 (Edler et al. 2020), using the “ML + rapid bootstrap” option, determining the number of bootstrap replicates by the autoMRE method. Prior to concatenation, single locus trees (see Treebase submission) were generated. No conflicts were detected using the principle by Kauff and Lutzoni (2002), assuming a conflict to be significant if two different relationships for the same set of taxa, one being monophyletic and the other non-monophyletic, are supported by bootstrap with more than 70% in ML analyses. Based on the results of Eberhardt et al. (2015b), the data were analyzed unpartitioned. Hebeloma louiseae was used for rooting following Beker et al. (2016).

Table 2.

Hebeloma database references (see Beker et al. 2016), country, voucher and GenBank accession numbers of sequences used for the ML analysis (Fig. 5B). BR-MYCO, C-F and L refer to the fungal collections of the Meise Botanic Garden (BR), the Herbarium of the University of Copenhagen (C), or Naturalis, Leiden (L), respectively. Vouchers with numbers starting with AdH, AT, or HJB are from the private collections of A.F.S. Taylor, A. de Haan or H.K.J. Beker.

Hebeloma database reference Country Voucher ITS GenBank acc. no. Tef1a GenBank acc. no. Rpb2 GenBank acc. no.
Hebeloma aanenii
HJB10282 Belgium HJB10282 JN943877 KT216789 KF309471
HJB10670 Sweden AT2003063 KM390550 KT216808 KM390126
HJB12630 holotype Poland BR-MYCO 173987-66 KM390723 KT216852 KM390169
Hebeloma alpinum
HJB11051 Iceland HJB11051 JN943865 MW452578 KF309496
HJB11094 Switzerland HJB11051 KM390594 KM390595 KT216817 KM390142
HJB11117 Switzerland HJB11051 KM390593 KT216819 KM390141
Hebeloma arcticum
HJB16687 Greenland C-F-103584 MW445563 MW452581 MW452590
HJB17506 Greenland C-F-106751 MW445580 MW452583 MW452592
HJB17673 holotype Greenland C-F-104149 MW445587 MW452584 MW452593
HJB17680 Greenland C-F-104080 MW445588 MW452585 MW452594
Hebeloma aurantioumbrinum
HJB12058 holotype Norway, Svalbard BR-MYCO 173985-64 KM390686 KM390687 KT216845 KM390158
HJB12445 U.S.A. HJB12445 KM390714 KM390715 KT216851 KM390166
HJB12451 U.S.A. HJB12451 KM390720 KM390721 MW452577 KM390168
Hebeloma crustuliniforme
HJB11237 Spain JN943870 KT216824 KF309480
HJB12807 Netherlands L WBS 9581 KF309415 KT216854 KF309492
HJB13713 epitype France BR-MYCO 173989-68 KF309424 KT216860 KF309495
Hebeloma eburneum
HJB9267 U.K., England HJB9267 JN943880 KT216777 KF309468
HJB10290 Belgium HJB10290 KM390533 KM390534 KT216792 KM390113
HJB12670 Poland HJB12670 KM390727 KM390728 KT216853 KM390171
Hebeloma geminatum
HJB8633 Belgium HJB8633 KM390526 KT216769 KM390109
HJB10384 U.K., England HJB10384 KF309400 KT216794 KF309472
HJB10833 holotype Denmark C-F-90152 KF309405 KT216815 KF309478
Hebeloma helodes
HJB8115 U.K., Wales HJB8115 KM390527 KT216768 KM390110
HJB10680 U.K., England HJB10680 KM390548 KT216810 KM390124
HJB11698 France HJB11698 KM390622 KT216831 KM390151
Hebeloma louiseae
HJB11984 Norway, Svalbard HJB11984 KM390705 KT216839 KM390164
HJB16602 Greenland C-F-103518 MW445557 MW452580 MW452589
HJB19601 Greenland C-F-106763 MW445592 MW452586 MW452595
Hebeloma luteicystidiatum
HJB11837 holotype Belgium BR-MYCO 166233-72 KM390624 KT216837 KM390152
HJB12174 Belgium HJB12174 KM390710 KT216978
HJB16715 France HJB EG-151028.02 MW465839 MW452582 MW452591
Hebeloma lutense
HJB 9819 U.K., Scotland JN943871 KT216783 KF309479
HJB 10523 Belgium AdH04059 KM390541 KT216798 KM390119
HJB11328 France HJB11328 JN943864 KT216825 KF309486
Hebeloma matritense
HJB9485 holotype Spain BR-MYCO 174910-19 KT217364 KT216781 KT216879
HJB9486 Spain HJB9486 KT217365 KT216782 KT216880
Hebeloma minus
HJB11079 Iceland HJB11079 JN943866 KT216816 KF309481
HJB11107 Switzerland HJB11107 JN943868 KT216818 KF309483
HJB12007 Norway, Svalbard HJB12007 JN943857 KT216842 KF309488
Hebeloma pallidolabiatum
HJB11992 holotype Norway, Svalbard BR-MYCO 174908-17 KM390702 KM390703 KT216840 KM390163
HJB12059 Norway, Svalbard HJB12059 KM390713 KT216846 MW452587
Hebeloma perexiguum
HJB12038 holotype Norway, Svalbard BR-MYCO 173979-58 KM390689 KT216844 KM390160
Hebeloma pusillum
HJB9494 U.K., Wales HJB9494 KM390530 KM390111
HJB11728 Belgium HJB11728 JN943862 KT216835 KF309497
HJB14747 U.K., Isle of Man HJB14747 MW465838 MW452579 MW452588
Hebeloma salicicola
HJB10260 Belgium HJB10260 KF309403 KT216788 KF309470
HJB10422 Belgium HJB10422 JN943878 KT216795 KF309473
HJB 13302 holotype Belgium BR-MYCO 173977-56 KM390683 KT216857 KM390177

Morphological methods

All microscopical analysis was carried out on dried material, using a Leica DMRZA2 microscope with a Leica DFC495 camera connected to a computer running Leica Application Suite (LAS) V4 software. The spores were first studied in Melzer’s reagent to assess the shape, degree of dextrinoidity, ornamentation and the degree of loosening of the perispore. For the assessment of the degrees of ornamentation (O0, O1, O2, O3, O4), of the loosening perispore (P0, P1, P2, P3) and for the dextrinoidity (D0, D1, D2, D3, D4), we used Beker et al. (2016), where more details can be found.

A number of photographs were taken of the spores at x500 and x1600, which were then measured using the LAS software. Wherever possible, for each collection at least 50 spores were measured in Melzer’s reagent, excluding the apiculi. The maximum length and width of each spore was measured, and its Q value (ratio of length to width) calculated. Average length, width, and Q value were calculated and recorded, as well as the median, standard deviation, and 5% and 95% percentiles. Photographs were also taken of the cheilocystidia on the lamella edge at x500 and of individual cystidia and basidia at x1000. The material was then examined in 5% KOH. Again, photographs were taken of the spores at x500 and x1600 and of the cheilocystidia (and pleurocystidia if any were present) and basidia at x500 and x1000.

For the cheilocystidia, the average width of the widest part of the cheilocystidium in the vicinity of the apex appears to be an important character in the separation of species within Hebeloma (Vesterholt 2005). It is also important, when determining this average width near the apex, not to be selective with regard to the cystidia chosen for measurement. To determine the average width at the apex about 100 cheilocystidia were measured on the lamellae edge. For other measurements, at least 20 cheilocystidia, wherever possible, separated from the lamella edge, were measured from each collection. Because of the complex shapes of the cheilocystidia four measurements were made: length, width at apex (A), width at narrowest point in central region (M), and maximum width in lower half (B). The measurements were given in this order, and an average value was calculated for each of these measurements. For each cheilocystidium the ratios A/M, A/B, and B/M were calculated and averaged across all cheilocystidia measured. Separate mountings of the material were used, where possible, to examine the caulocystidia and pileipellis.

Morphological terms, including colors, are as in Beker et al. (2016), which we have used as the basis for the descriptions, emending some of them where new data from new collections became available.

Results

Of the 405 collections studied, sequence data was generated from 378, which formed the basis of this study. The overall distribution of the sample is shown in Fig. 2A, but the main collection sites starting with the most southerly were Narsarsuaq, Paamiut, Kangerlussuaq, Zackenberg and Jameson Land.

Figure 2. 

Hebeloma species collecting sites in Greenland A all B collection sites in the Low Arctic, encompassing groups 1–3, and C in the High Arctic, encompassing group 5.

The combined morphological and molecular analysis determined the presence of 28 species, of which one, H. arcticum, is described as new to science. For another, H. colvinii, the first modern description is provided. The others are H. alpinicola, H. alpinum, H. aurantioumbrinum, H. clavulipes, H. dunense, H. excedens, H. fuscatum, H. geminatum, H. grandisporum, H. helodes, H. hiemale, H. hygrophilum, H. ingratum, H. islandicum, H. leucosarx, H. louiseae, H. marginatulum, H. mesophaeum, H. minus, H. nigellum, H. oreophilum, H. pubescens, H. spetsbergense, H. subconcolor, H. vaccinum and H. velutipes. Nineteen of these taxa are new records for Greenland and six are new records for the North American continent: H. clavulipes, H. grandisporum, H. islandicum, H. louiseae, H. minus and H. pubescens. Three species, H. arcticum, H. colvinii and H. excedens have not been recorded from Europe.

Geographical distribution of Hebeloma species in the sample

The 28 species all occur in the Arctic zone. In the small Subarctic zone in southernmost Greenland (< 61.25°N), 13 species were recorded, but they also occurred in the Arctic zone. Below, the species are grouped according to the regions within which they occur; Table 3 lists the species in each group.

Table 3.

Hebeloma species composition of the Greenland sample by species distribution groups (see main text). Classification into “specialist” and “opportunist” taxa follows Beker et al. (2016).

Species by region No. of collections Specialist (S) or opportunist (O)
Group 1 – South Greenland (60.9–62°N)
H. clavulipes 1 O
H. helodes 5 O
H. islandicum 1 S
H. leucosarx 2 O
Group 2 – South & West Greenland (60.2–69.3°N)
H. arcticum 8 S
H. colvinii 5 O
H. excedens 3 O
H. geminatum 3 O
H. hygrophilum 15 O
H. ingratum 4 O
H. minus 2 S
Group 3 – South, West & East Greenland (60.1–72.8°N)
H. fuscatum 8 S
H. nigellum 21 S
H. subconcolor 9 S
Group 4 – All of Greenland (60.1–81.6°N)
H. alpinicola 13 S
H. alpinum 36 S
H. aurantioumbrinum 40 S
H. dunense 42 S
H. hiemale 44 O
H. marginatulum 42 S
H. mesophaeum 11 S
H. oreophilum 18 S
H. vaccinum 13 O
H. velutipes 10 O
Group 5 – Never collected in South Greenland (67–74.5°N)
H. grandisporum 2 S
H. louiseae 5 S
H. pubescens 3 S
H. spetsbergense 12 S
Total 378
  • Group 1. Four species appear to have a southerly distribution and are only known from South Greenland (< 62.2°N): H. clavulipes, H. helodes, H. islandicum and H. leucosarx.
  • Group 2. Seven species appear to have a southwesterly distribution, i.e. are known from just southern and western Greenland (< 69.25°N): H. arcticum, H. colvinii, H. excedens, H. ingratum, H. geminatum, H. hygrophilum and H. minus.
  • Group 3. Only three species have been collected in southwestern and south-eastern Greenland but not northern Greenland (< 67°N): H. fuscatum, H. nigellum and H. subconcolor.
  • Group 4. Ten species have been collected all over Greenland in Subarctic, Low Arctic and High Arctic zones: H. alpinicola, H. alpinum, H. aurantioumbrinum, H. dunense, H. hiemale, H. marginatulum, H. mesophaeum, H. oreophilum (not collected in east Greenland), H. vaccinum (not collected in west Greenland), and H. velutipes.
  • Group 5. Four species are northern and have never been collected in south Greenland (> 67°N). They have only been verified for the High Arctic zone: H. grandisporum, H. louiseae, H. pubescens and H. spetsbergense.

Fourteen species are only found in the southern half of Greenland (groups 1, 2 and 3; Table 3 and Fig. 2B, the Subarctic and Low Arctic zones defined by at least six months with an average temperature above zero: H. arcticum, H. clavulipes, H. colvinii, H. excedens, H. fuscatum, H. geminatum, H. helodes, H. hygrophilum, H. ingratum, H. islandicum, H. leucosarx, H. minus, H. nigellum and H. subconcolor. Four species have never been recorded from south Greenland. This is Group 5, above and see also Table 3 and Fig. 2C.

Molecular results

Full ITS sequence data was obtained from 367 Greenland collections; 10 collections, indicated in Table 1, only yielded either ITS1 or ITS2 sequences. These sequences were compared to existing sequence data and supported the morphological identifications. They are not included in the molecular analyses.

The data was divided into seven datasets for the network analyses and are depicted in Figs 37: Three networks for H. sect. Hebeloma, three networks for H. sect. Denudata and one for H. sect. Velutipes. The molecular result for the Greenland H. islandicum collection is treated in the Taxonomy part where the species is discussed.

Figure 3. 

Pruned quasi-median networks of A the Hebeloma mesophaeum complex and B Hebeloma marginatulum. Circles shared by two or more taxa or collections from two regions, from Greenland (G) or collected elsewhere, are divided according to the number of representatives for each class.

The H. mesophaeum complex network (Fig. 3A) includes 124 sequences of which 76 are from Greenland material. The only species which has ‘private’ ITS variants, i.e. not mixing with other species’ sequences, is H. colvinii. Fourteen collections of H. alpinicola and six of H. dunense have ITS variants that occur in both species. The overlap concerns only Greenland collections of H. alpinicola, although Greenland collections do not generally appear to be segregated from non-Greenland collections. Some (5) H. mesophaeum ITS variants coincide with H. excedens (7) and others (11) with H. pubescens (6), irrespective of geographical origin.

No overlap was observed between H. marginatulum ITS variants and those of other species. The network (Fig. 3B) gives evidence of the ITS sequence diversity of the species. The network includes 92 sequences, of which 42 were from Greenland. The circles representing only non-Greenland collections in the upper part of the network only include North American sequence variants, but other North American collections are also represented by circles in the lower part of the diagram. The ITS of the Greenland collections do not appear to stand out in this circumpolar sample.

Fig. 4A shows the network of the H. nigellum complex and H. grandisporum. The analysis included 144 sequences of which 73 stemmed from Greenland material. Only a partial ITS sequence of the single collection of H. clavulipes from Greenland could be generated and was thus not included in the analysis. Hebeloma grandisporum is the only species in this network that is distinct; it is separated by at least 5 alignment positions from the sequences of the members of the H. nigellum complex. The ITS of H. fuscatum is split between one group of sequences that differs in at least 3 alignment positions from all other sequences in the analyses and a number (5) of Greenland collections that group together with sequences of H. oreophilum (20) and H. clavulipes (7). The latter two species are not separable by ITS. Similarly, H. nigellum cannot be separated from H. spetsbergense; 29 collections of H. nigellum and 12 of H. spetsbergense are represented in the shared circles. Some collections of H. hygrophilum (4) mix with H. nigellum and H. spetsbergense in the network.

Figure 4. 

Pruned quasi-median network of A the Hebeloma nigellum complex and H. grandisporum and B Hebeloma cavipes, H. ingratum and H. vaccinum. Circles shared by two or more taxa or collections from two regions, from Greenland (G) or collected elsewhere, are divided according to the number of representatives for each class.

Fig. 5A shows the ITS network of the H. alpinum complex in a broad sense, including H. minus and H. pallidolabiatum, as well as H. louiseae and H. arcticum. The latter species is described as new in this paper. The network includes 109 sequences, of which 54 are from Greenland material. Eight species are included in the network; five of these have been collected in Greenland and H. arcticum is represented exclusively by Greenland material. Hebeloma louiseae and H. arcticum are clearly distinct and do not share any ITS variants with other species. All member species of the H. alpinum complex, in this broad sense, either have some members that are represented in the central circle of the network or are linked through it (H. pallidolabiatum). All members of H. geminatum (12) and the majority of collections of H. alpinum (35), irrespective of origin, are represented in the central circle. Additional information on the results referring to H. arcticum are given in the context of the species description below.

Figure 5. 

A Pruned quasi-median network of the Hebeloma alpinum complex, H. arcticum and H. louiseae. Circles shared by two or more taxa or collections from two regions, from Greenland (G) or collected elsewhere, are divided according to the number of representatives for each class B ML result for Hebeloma subsect. Crustuliniforme, based on concatenated ITS, RPB2 and Tef1a data, rooted with H. louiseae. Thick branches indicate bootstrap support of at least 80% (450 bootstrap replicates). Species are represented by three collections (if available); Hebeloma arcticum by four collections including the holotype.

In Fig. 5B the position of H. arcticum within H. subsect. Crustuliniformia is shown in the result of the ML analysis. The species clade of Hebeloma arcticum received full bootstrap support (100%) and formed a highly supported clade (99%) with the species clades of H. aurantioumbrinum, H. helodes, H. luteicystidiatum, H. lutense, H. matritense, H. perexiguum and H. pusillum all of which are also fully supported, apart from H. perexiguum which is only known from the type.

The networks relating to other members of H. sect. Denudata are depicted in Figs 4B, 6A and 6C. The network of members of H. subsect. Clepsydroida (Fig. 4B) includes 47 sequences (16 from Greenland) from three species. Hebeloma ingratum is distinct from the other two species in the network, separated by at least 5 alignment positions.

Sequences from Europe and Greenland are represented in the same circle. Hebeloma cavipes (4 sequences), not present in Greenland and H. vaccinum (13 sequences) share one ITS variant; there is no taxonomic or geographical structure apparent in the H. cavipes/H. vaccinum part of the network.

Hebeloma hiemale (Fig. 6A), not unlike H. marginatulum, is a species that is distinct from its relatives based on ITS, but with a high intraspecific variation in the ITS. Greenland collections (42 out of a total of 86 sequences in the analysis) are concentrated in the upper part of the network, but the circles that only include non-Greenland collections include European as well as North American collections.

Figure 6. 

Pruned quasi-median networks of A the Hebeloma velutipes complex B H. hiemale and C H. aurantioumbrinum and H. helodes. Circles shared by two or more taxa or collections from two regions, from Greenland (G) or collected elsewhere, are divided according to the number of representatives for each class.

The network of H. aurantioumbrinum and H. helodes (Fig. 6C) shows that in Greenland H. helodes cannot be distinguished based on ITS (the mixed circle represents three sequences of H. helodes and one of H. aurantioumbrinum, all from Greenland), although outside Greenland H. helodes appears to be better distinct from H. aurantioumbrinum. The network is based on 80 sequences, of which 43 are of Greenland origin.

Three species of H. sect. Velutipes have been collected in Greenland. The respective network is depicted in Fig. 6B and is based on 65 sequences of which 20 were from Greenland collections. Hebeloma leucosarx differs by at least one alignment position from the other two species; H. subconcolor and H. velutipes sequences are represented by the biggest circle (28 sequences) of the network. Neither in the Greenland sample nor in the US sample, did H. velutipes ITS variants occur that were more similar to H. incarnatulum (at the bottom of the network; see figure 5 of Cripps et al. (2019) for the placement of H. incarnatulum) than to H. leucosarx. The circle representing H. subconcolor and H. velutipes includes 17 sequences from the former and 11 from the latter.

Taxonomic treatment

Hebeloma (Fr.) P. Kumm.

General description

Cap 0.9–21 cm, convex or more rarely campanulate or applanate, rarely depressed at center, dry, in wet weather viscid in some species, or tacky, smooth or rarely scaly, margin even or undulate, smooth, rarely hygrophanous, rarely striate, several shades of brown, from whitish to pale beige to dark brown, occasionally orange-brown, rarely reddish brown, along margin with or without remnants of universal veil, floccose or velutinate. Lamellae emarginate to adnate, thin, unicolored, at first pale, at maturity browner, in some groups with hyaline or brown droplets along margin. Stem 2.0–14.0 × 0.1–2.0 cm, cylindrical or bulbous at base, occasionally rooting, at first white, whitish or cream, becoming pale ochraceous to brown or even black, white tomentose, floccose or pruinose, rarely velutinate, some groups with partial veil, rarely with a membranous ring. Flesh color resembling the color of the stem, often discoloring brownish from stem base when bruised or old. Smell often radish-like, in one section sweetish, in some species insignificant. Taste mild to bitter, rarely significant. Spore deposit umber to dark cinnamon or dark brick red.

Spores most often amygdaloid, also ellipsoid or limoniform, rarely fusoid or navicular, in some species distinctly papillate, from pale yellow to dark brown, almost smooth to distinctly verrucose and ornamented with separate or coherent irregular warts, in some groups with ± loosening perispore, in Melzers solution from indextrinoid to distinctly and strongly dextrinoid. Cheilocystidia present in all species, variable but distinctive, cylindrical, lageniform, slenderly clavate, spheropedunculate, ventricose or balloon-shaped or variations thereof, rarely forked, in some species partially thick-walled, straight, sinuate or geniculate, hyaline or pale brown. Pleurocystidia rarely present, when present usually similar to cheilocystidia. Caulocystidia present in all species, similar to cheilocystidia, often fasciculate. Basidia cylindrical to slenderly clavate, 4-spored, rarely also 2-spored, in one arctic species only 2-spored. Pileipellis an ixocutis, a thin layer of narrow, hyaline hyphae, smooth or encrusted, 30–250 µm thick.

Comments

Hebeloma is a genus of ectomycorrhizal fungi. The symbionts belong to a wide variety of families of dicotyledons. In Greenland, according to the observations of T.B., S.A.E. and H.K.K. symbionts appear to belong to the families: Salicaceae, Betulaceae, Polygonaceae and Rosaceae. The total list consists of only 11 species: Salix glauca, S. herbacea, S. arctica Pall., S. arctophila, Betula pubescens var. pumila, B. nana., B. glandulosa, Alnus alnobetula subsp. crispa, Bistorta vivipara, Dryas octopetala and D. integrifolia.

Bistorta vivipara (L.) Delarbre (≡ Polygonum viviparum L., Polygonaceae) has often been observed close to species of Hebeloma and Brevik et al. (2010) isolated sequences of Hebeloma spp. from its roots in Spitsbergen, which is normally considered as a strong indication that this plant associates with the respective fungus. In a few cases, T.B. found rhizoids from Hebeloma attached to the roots of Bistorta, but found it difficult to rate the importance of these observations, since there have often been other possible hosts observed nearby. For Alnus, there is no evidence that it is a host; for the few records from Alnus-shrubs, it is not possible to rule out nearby willows or birches. The remaining perennial shrubs in Greenland, Sorbus groenlandica (C.K. Schneid.) Á. Löve & D. Löve and Juniperus communis L. do not form ectomycorrhiza. This is also the case for members of the heather family (Ericaceae) that occur in Greenland, with the rare exception of Arctostaphylos alpina.

Key to sections and subsections of Hebeloma in Greenland, (including H. islandicum)

Spore character measures (O1O4; P0P3 and D0D4) are explained in Beker et al. (2016: 22ff and figure 6A–G (color)).

1 Veil present, either on the cap margin or from the margin to the stem or both; margin of lamellae rarely exuding small drops; most cheilocystidia distinctly ventricose H. sect. Hebeloma
Veil absent (except in primordia); margin of lamellae when fresh usually exuding droplets; most cheilocystidia distinctly swollen at apex 2
2 Cheilocystidia at apex and base enlarged (hourglass-shaped), apically or in the middle sometimes with thickened walls 3
Cheilocystidia distinctly enlarged at apex, below ± cylindrical, walls rarely thickened 5
3 Spores O2 and not O3 and many spores D3, found in alpine-arctic habitats H. islandicum
Above conditions not satisfied 4
4 Many spores O1 or O2 and many spores D0 or D1 and spores not P2 or if spores are P2 then pileus is not yellow or cream in the center but with brown or buff tones H. hiemale (H. subsect. Hiemalia)
The above conditions not satisfied H. subsect. Clepsydroida
5 Cheilocystidia distinctly restricted below apex, hardly swollen in lower third H. subsect. Crustuliniformia
Cheilocystidia more gently tapering downwards, some ventricose cystidia present H. sect. Velutipes

Key to species of Hebeloma section Hebeloma in Greenland

1 Spores mainly ellipsoid, indextrinoid to weakly dextrinoid 2
Spores mainly amygdaloid, usually rather strongly to strongly dextrinoid 8
2 Number of full-length lamellae (L) < 32 and pileus with a matting of short soft hairs H. pubescens
Number of full-length lamellae ≥ 32 or if < 32 then pileus with at most a few fibrils at margin 3
3 Spores on ave. at least 12.5 × 7.5 µm H. colvinii
Spores smaller 4
4 Cap distinctly bicolored, at least in mature specimens H. mesophaeum
Cap mainly unicolored, at most indistinctly bicolored 5
5 Spores clearly ellipsoid to ovoid, very rarely amygdaloid, ave. size rarely exceeding 10 × 6 µm 6
Ave. spore length > 10 μm and ave. spore width ≥ 6 μm or if spores smaller, then most spores ellipsoid, but many amygdaloid, almost always with Salicaceae 7
6 Stem relatively narrow, usually 0.2–0.6 cm thick, cap often overhanging lamellae H. excedens
Stem relatively robust, usually 0.5–1 cm thick, cap not overhanging lamellae H. alpinicola
7 Spores with some clear ornamentation (O1,O2) and an indistinct but clear reaction in Melzer’s reagent (D1) H. dunense
Spores showing almost no ornamentation, even under immersion (O1) or completely indextrinoid (D0) H. marginatulum
8 Number of full-length lamellae (L) ≥ 40 9
Number of full-length lamellae (L) < 40 10
9 Spores, on ave. ≥ 6.7 µm wide H. oreophilum
Spores, on ave. < 6.7 µm wide H. clavulipes
10 Ave. spore length ≥ 15 μm H. grandisporum
Ave. spore length < 15 μm 11
11 Spore papilla distinctly present and many spores limoniform H. fuscatum
Spore papilla at most indistinctly present and spores rarely limoniform 12
12 Ave. spore width > 7.5 μm H. spetsbergense
Spores amygdaloid 13
13 Spores < 7 µm wide H. hygrophilum
Spores ≥ 7 µm wide H. nigellum

Key to species of Hebeloma section Denudata in Greenland

1 Cheilocystidia at apex and base enlarged (hourglass-shaped), apically or in the middle sometimes with thickened wall 2
Cheilocystidia distinctly enlarged at apex, below ± cylindrical, walls rarely thickened 4
2 Spores on ave. 12–14.5 µm long, rather strongly dextrinoid (D3); cap at center rust brown to reddish brown H. vaccinum
Spores on ave. 10–12.5 µm long, less dextrinoid (D2); cap at center paler 3
3 Spores on ave. 10–11 µm long, O2 to O3, D1 to D2 H. ingratum
Spores on ave. 10–12.5 µm long, O1 to O2, Do to D1 H. hiemale
4 Number of full-length lamellae (L) ≥ 60 and ave. spore length < 11 μm H. geminatum
Number of full-length lamellae (L) < 60 or ave. spore length ≥ 11 μm 5
5 Spores O2 to O3 and D2 to D3, many D3 H. arcticum
Spores at most D2 6
6 Number of full-length lamellae (L) ≥ 40, spore length ≥ 11 μm, spores with distinct papilla H. alpinum
Any of the above conditions not satisfied 7
7 Ave. spore length < 11 μm 8
Ave. spore length ≥ 11 μm 9
8 Cheilocystidia without consistent and distinct apical thickening H. aurantioumbrinum
Cheilocystidia with consistent and distinct apical thickening H. helodes
9 Spores O1 or O2, few if any spores O3 H. louiseae
A large number of spores O3 H. minus

Key to species of Hebeloma section Velutipes in Greenland

1 No. of full-length lamellae < 35 H. subconcolor
No. of full-length lamellae > 35; stem base ± bulbose 2
2 Cap distinctly colored, often quite dark with reddish tones, umbonate H. leucosarx
Cap pale colored, whitish to beige or buff, convex, sometimes umbonate H. velutipes

Hebeloma sect. Hebeloma

Veil present, often along cap margin. Cap uniformly colored or bicolored, with a paler margin. Lamellae without droplets. Stem fibrillose, often browning from base. Spores ellipsoid, ovoid, amygdaloid or limoniform, ornamentation weak, dextrinoid or non-dextrinoid, perispore not or only very slightly loosening.

Hebeloma alpinicola A.H. Sm., V. S. Evenson & Mitchel; Veiled species of Hebeloma in the western United States (Ann Arbor): 48, 1983.

Fig. 7

Macroscopic description

Cap 1.2–4.5 cm in diameter, robust, fleshy, irregularly hemispherical to convex, somewhat domed or not, almost unicolored, center cinnamon to dark pinkish buff, dark olive buff or rarely umber, sometimes with grayish tones, outwards ocher and lighter buff not white towards margin, sometimes with hoary canescent coating that dries shiny, with weakly hygrophanous spots, dry, margin inrolled at first, and then turned down, partial veil present. Lamellae narrowly attached, slightly emarginate, or with a tooth, or pulling away, somewhat broad (2‒5 mm), pale gray brown to milky coffee, number of lamellae {L} 30–44, edges white floccose, without watery droplets. Stem 1.5–7.0 × 0.2–0.8 cm, cylindrical, whitish pruinose at apex, often with a whitish ring zone, dingy ocher to sordid yellowish or fairly dark brown, longitudinally strongly fibrillose and striate in lower part, often darkening when bruised, base sometimes encrusted with sand or earth, solid or slightly hollow. Context dingy whitish, darker below, unchanging or flesh staining brown. Smell weakly raphanoid. Taste almost insipid to slightly bitter. Spore deposit near fulvous.

Figure 7. 

Hebeloma alpinicola A HK18.322, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK18.322 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores ellipsoid or some slightly amygdaliform or ovoid, with rounded end, apiculus small, on ave. 8–10.5 × 5–6 µm, ave. Q = 1.55–1.85, smooth to slightly rough (O1), not guttulate, not or very slightly dextrinoid (D0 D1), perispore not loosening (P0). Basidia clavate, mostly four-spored, 20–35 × 6–8 µm. Cheilocystidia lageniform or ventricose, on ave. 35–55 × 5–6.5 (apex) × 4.5–6.5 (middle) × 6.5–10 (base) µm, occasionally geniculate or bifurcate, sometimes septate. Ratios A/M = 0.95‒1.24, A/B = 0.54‒0.88, B/M = 1.43‒2.17. Epicutis an ixocutis, up to 200 µm thick, maximum hyphae width to 8 µm, encrusted hyphae not seen, shape of trama elements beneath subcutis cylindrical. Caulocystidia similar to cheilocystidia, but generally larger.

Collections examined

S-Greenland: Kangilinnguit, 61.23°N, 48.07°W, 12 Aug 1985, T. Borgen (TB85.099, C-F-5082), 95 m, with Salix glauca and Chamaenerion latifolium in heathland. Kangilinnguit, 61.23°N, 48.10°W, 6 Aug 1984, T. Borgen (TB84.063, C-F-103534), 25 m, with Salix glauca in scrubland. Kangilinnguit, 61.23°N, 48.07°W, 17 Aug 1985, T. Borgen (TB85.071, C-F-5081), 95 m, with Alnus alnobetulae. Narsarsuaq, 61.15°N, 45.42°W, 9 Aug 2018, H. Knudsen (HK18.010, C-F-111109), 185 m, with Salix glauca and Betula pubescens in scrubland. Narsarsuaq, airport area, 61.08°N, 45.26°W, 3 Aug 1984, T. Borgen (TB84.028, C-F-103559), 20 m, with Salix glauca and Betula glandulosa in scrubland. Paamiut, 62.01°N, 49.4°W, 1 Aug 2000, T. Borgen (TB00.049, C-F-103516), 10 m, with Salix herbacea in snowbed. Paamiut, 62.01°N, 49.4°W, 8 Aug 1981, T. Borgen TB81.111, C-F-103554), 25 m. Paamiut, 62.01°N, 49.4°W, 20 Aug 1985, T. Borgen (TB85.218, C-F-103532), 30 m, with Salix herbacea and Bistorta vivipara in snowbed. W-Greenland: Kobbefjord, NuukBasic Station, 64.078°N, 51.23°W, 25 Aug 2018, H. Knudsen (HK18.322, C-F-111116), 5 m, with Salix herbacea in tundra. Sisimiut, Kællingehætten, 66.93°N, 53.59°W, 16 Aug 2016, H. Knudsen (HK16.165, C-F-108401), 400 m. N-Greenland: Zackenberg, Ulvehøj, 74.47°N, 21°W, 7 Aug 1999, T. Borgen (TB99.238, C-F-119805), 40 m, with Salix arctica and Bistorta vivipara. E-Greenland: Kuummiut, Torsukattak, 65.87°N, 37.01°W, 2 Aug 2008, T. Borgen (TB08.039, C-F-101623), 35 m; with Salix glauca in heathland. Kuummiut, Torsukattak, 65.87°N, 37.01°W, 2 Aug 2008, T. Borgen (TB08.037, C-F-101621), 35 m.

Distribution

Widely distributed in Greenland, only missing in Constable Pynt. Originally described from the Seven Devils Mountains in Idaho, North America by Smith et al. (1983), more recently from the Rocky Mountains by Cripps et al. (2019) and from the European Alps by Grilli et al. (2020). This species appears to favor both boreal and arctic or alpine habitats. Most collections from Rocky Mountains were from subalpine areas. In Greenland, it occurs from the Subarctic zone to the High Arctic zone, and the Greenland collections from Zackenberg are the northernmost known (74.47°N). Circumpolar, arctic-alpine.

Habitat and ecology

Thirteen collections in all, mainly with Salix glauca in scrubs and heathland, three collections in snowbeds with S. herbacea, one collection with S. arctica, and one collection with Alnus alnobetulae ssp. crispa, but the presence of other possible associates should not be ruled out. In the Rocky Mountains, Cripps et al. (2019) found two collections, one with Dryas, Salix planifolia Pursh. and S. reticulata L., the other subalpine record with dwarf willows only. Hebeloma alpinicola seems not to be specific regarding soil conditions.

Hebeloma clavulipes Romagn.; Bull. trimest. Soc. mycol. Fr. 81(3): 326, 1965.

Fig. 8

Macroscopic description

Cap 1.0‒4.1 cm in diameter, convex, sometimes umbonate, margin involute, rarely sulcate, tacky when moist, sometimes hygrophanous, uniformly colored or variably bicolored, at center umber to sepia (6E6, 6E7, 6F6, 6F7), margin cream to pinkish-buff to ochraceous or dark olive buff (4A2, 4A3, 5A3, 5B3, 5B5, 5C5); remains of universal veil sometimes present; partial veil present. Lamellae adnate or adnexed to emarginate, pale brown, maximum depth 3‒5 mm, number of lamellae {L} 40‒48, droplets usually absent, but occasionally visible with × 10 lens, white fimbriate edge usually present, but sometimes indistinctly. Stem 1.3‒7.0 × 0.3‒0.6 cm, 4.5‒7.3(–8) cm at base, stem Q 3.3‒15.5(–18), at first whitish fibrillose becoming pale brown, base cylindrical to clavate or bulbous, usually pruinose or floccose at apex. Context firm, stem inside stuffed, later hollow, stem flesh discoloring from base, sometimes weakly. Smell raphanoid, sometimes with hints of cocoa. Taste mild to bitter, usually raphanoid. Spore deposit brownish olive (5E5).

Figure 8. 

Hebeloma clavulipes A JV02-517 (from Denmark), photo J. Vesterholt, reproduced by kind permission from Beker et al. (2016) B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of TB90.100 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid or limoniform, occasionally appearing ovoid or fusoid, on ave. 10.5‒12.5 × 6.0‒6.5 µm, ave. Q 1.6‒2.1, very weakly ornamented (O1 O2), perispore not or somewhat loosening (P0 P1), rather strongly dextrinoid (D2 D3), yellow to yellow brown, ± guttulate, papillate. Basidia 23‒32(‒36) × 7‒10 µm, ave. Q = 2.6‒4.4, mostly four-spored. Cheilocystidia lageniform to ventricose, occasionally cylindrical, occasionally with a characteristic thickening, apically, basically or medially, sometimes geniculate or septate, on ave. 41‒60 × 4.5‒6 (apex) × 4‒5.5 (middle) × 7.5‒12 (base) µm, ratios A/M = 0.93‒1.25, A/B = 0.45‒0.76, B/M = 1.58‒2.31. Epicutis an ixocutis, 125–170 µm thick (measured from exsiccata), maximum hyphae width 3.5‒7 µm, sometimes encrusted, shape of trama elements beneath subcutis sausage-shaped, up to 14 µm wide. Caulocystidia similar to cheilocystidia, but usually less ventricose, up to 120 µm long.

Collections examined

S-Greenland: Paamiut, W of the Navigation School area, 62°N, 49.67°W, 7 Sep 1990, T. Borgen (TB90.100, C-F-119760), 20 m, with Salix herbacea.

Distribution

Only one record and apparently a very rare species in Greenland recorded only once during the 20 years when Borgen regularly collected in Paamiut. The general distribution in Europe (Beker et al. 2016) is from the Temperate zone to southern Boreal and Subalpine zone up to 1700 m. The Greenland record is the northernmost known (62.00°N). Temperate, boreal, subarctic, and now also from Low Arctic zone.

Habitat and ecology

Only one collection, with Salix herbacea. In Europe, the hosts are Betula, Picea and Salix (Beker et al. 2016), but the associated Salix species are of the shrub-like kind, like S. aurita.

Hebeloma colvinii (Peck) Sacc.; Syll. fung. (Abellini) 5: 805, 1887.

Fig. 9

Macroscopic description

Cap 2.5–7.5 cm, convex to irregularly gibbous, sometimes broadly umbonate, with incurved later straight, opaque margin, occasionally appendiculate, dry and dull, unicolored mainly sepia, sometimes with light grayish adpressed covering. Lamellae almost free to emarginate gray (olive) brown, edge entire, slightly tomentose, number of lamellae {L} 45–58. Stem whitish pale fibrillose, sordid gray-brown, often more or less buried in sand with a sand bulb around the base, cortina pale. Context initially fairly thick, with cavity, firm watery grayish in pileus, pale brownish in stipe to near buff, towards base dark, sordid brown. Smell weakly and indistinctly raphanoid. Taste similar, mild. Spore deposit color not recorded.

Figure 9. 

Hebeloma colvinii A HK16.005, photograph H. Knudsen B distribution of cited collections; C spores ×1600 and D cheilocystidia ×1000 of HK16.005 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores ellipsoid, often ovoid or amygdaloid on ave. 12.0‒14.5 × 7.5‒8.5 µm, ave. Q 1.5‒1.9, very weakly ornamented (O1 O2), perispore not noticeably loosening (P0), indistinctly dextrinoid (D0 D1), yellow brown, ± guttulate, not papillate. Basidia 26‒42 × 7‒11 µm, ave. Q = 3.0‒4.2, mostly four-spored. Cheilocystidia lageniform to ventricose, occasionally cylindrical or clavate-ventricose, occasionally with a characteristic wall thickening, apically, basically, sometimes septate, on ave. 40‒50 × 5.5‒8 (apex) × 5‒9 (middle) × 10‒13 (base) µm, ratios A/M = 0.90‒1.26, A/B = 0.46‒0.77, B/M = 1.40‒2.45. Epicutis an ixocutis, up to 120 µm thick (measured from exsiccata), maximum hyphae width 10 µm, sometimes encrusted, shape of trama elements beneath subcutis sausage-shaped, cylindrical or ellipsoid. Caulocystidia similar to cheilocystidia, but usually less ventricose, up to 130 µm long.

Collections examined

S-Greenland: Narsarsuaq, 61.16°N, 45.43°W, 31 Aug 2002, T. Borgen (TB02.166, C-F-106756), 30 m, with Salix glauca in riverbed. W-Greenland: Kangerlussuaq, Sandflugtsdalen, 67.13°N, 51.16°W, 7 Aug 2016, T. Borgen (TB16.075, C-F-103585), 50 m, with Salix glauca at riverside dune. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.46°W, 7 Aug 2016, H. Knudsen (HK16.008, C-F-104038), 200 m, with Salix glauca. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.46°W, 7 Aug 2016, H. Knudsen (HK16.005, C-F-104035), 200 m, with Salix glauca. Kangerlussuaq, southeast of Sugar Loaf, 66.989438°N, 50.548760°W, 25 Aug 2015, S.A. Elborne (SAE-2016.188GR, C-F-107346), 50 m with Salix glauca at riverside dune.

Distribution

Known from a few collections from three localities in southwestern Greenland. H. colvinii was described by Peck (1875; effectively published 1876) from West Albany in North America. He found it in drifting sand in West Albany near Albany, N.Y. State. Later Kauffman (1918) reported this or a very similar species from New Richmond in Michigan, as did Ritchie (1946) from Lewes, Delaware Bay. Neither of these two collections has been examined as part of this study.

Habitat and ecology

Five collections, all with Salix glauca in pure sand along a river. In one of the localities, Sandflugtsdalen (“valley of driftsand”) at Kangerlussuaq, it was very common and scattered over a large area. The sand is mineral-rich due to mixing with loess.

Note

Hebeloma colvinii was originally described as “Agaricus colvini” (Peck 1875). The name is currently not in use, e.g. there are no records on Mushroom Observer (https://mushroomobserver.org/, accessed 23 Sept 2020) and while Mycoportal (https://mycoportal.org/portal/collections/list.php, accessed 2 Dec 2020) has 63 records, the most recent is from 1972. The identification of the Greenland collections is supported by unpublished studies of type material. It appears that exposed expanses of sandy soil are the characteristic habitat for the species, which is morphologically similar to a number of species of the difficult group around H. dunense and H. mesophaeum. Hebeloma colvinii can be recognized by its large ellipsoid spores, reminiscent of Hebeloma psammophilum, which is currently known only from western Europe (Beker et al. 2016).

Hebeloma dunense L. Corb. & R. Heim; Mém. Soc. natn. Sci. nat. Cherbourg 40 (2): 166, 1929.

Fig. 10

Macroscopic description

Cap 1.0–7.0 cm in diameter, convex to umbonate, sometimes papillate, sometimes umbilicate, margin often involute when young, sometimes scalloped or serrate, becoming wavy or upturned with age, sometimes fibrillose along margin, tacky when moist, sometimes but not consistently hygrophanous, uniformly colored or variably bicolored, at center clay buff, dark olive buff, ochraceous or yellowish brown to brownish olive or umber or sepia to dark brick or orange brown or fuscous, at margin cream to buff or honey to pinkish buff to dark olive buff or yellowish brown to umber or sepia, sometimes with remains of universal veil, partial veil present. Lamellae light gray brown or very pale clay, later brownish clay, adnexed to adnate, usually emarginate, sometimes with decurrent tooth and occasionally decurrent, maximum depth 2.5–9 mm, number of lamellae {L} 20–48, droplets usually absent, but occasionally visible with ×10 lens, white fimbriate edge usually present, but often weak. Stem (1.0–)1.4–8.0 × (0.2–)0.3–1.2 cm, at base 0.2–1.0(–1.2) cm, stem Q = 3.5–15, base cylindrical, sometimes slenderly clavate, occasionally with sand bulb, fibrillose, pruinose or floccose at apex. Context firm, stem interior stuffed, later hollow, occasionally with superior wick, flesh usually discoloring from base, sometimes very strongly. Smell raphanoid, rarely without smell, occasionally hints of cocoa; taste mild to raphanoid to bitter. Spore deposit dark olive buff to brownish olive to umber to fuscous or sepia.

Figure 10. 

Hebeloma dunense A SAE-2017.103, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2017.103 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores mainly ellipsoid, some amygdaloid or ovoid, not papillate, 10.0–12.5 × 6.0–7.5 µm, ave. Q 1.5–1.9, very weakly ornamented (O1 O2), perispore not or somewhat loosening (P0 P1), indistinctly dextrinoid (D0 D1), yellow through yellow brown to brown, ± guttulate. Basidia 20–33 × 7–9 µm, ave. Q = 2.8–4, mostly four-spored. Cheilocystidia usually lageniform or ventricose, sometimes cylindrical, occasionally with characteristic wall thickenings, apically, medially or basically, occasionally bifurcate, geniculate, septate (sometimes clamped), subcapitate, 34–57 × 4.5–8 (apex) × 4–7 (middle) × 7–12 (base) µm, with yellow contents, ratios A/M = 0.82–1.43, A/B = 0.42–0.89, B/M = 1.4–2.14. Epicutis an ixocutis, 25–75 µm thick (measured from exsiccata), ixocutis maximum hyphae width 4–8 µm, hyphae occasionally encrusted, shape of trama elements beneath subcutis angular, ellipsoid, isodiametric, spherical or sausage-shaped up to 20 µm wide. Caulocystidia similar to cheilocystidia, but usually more irregular and often multi-septate.

Collections examined

S-Greenland: Kangilinnguit, 61.14°N, 48.6°W, 15 Aug 1985, T. Borgen (TB85.200, C-F-103530), 400 m, with Salix herbacea and Dryas integrifolia in snowbed. Kangilinnguit, 61.23°N, 48.10°W, 8 Aug 1984, T. Borgen (TB84.090, C-F-103535), 25 m, with Salix herbacea along streamside. Kangilinnguit, at Grønnedal Hut, 61.23°N, 48.08°W, 15 Aug 1985, T. Borgen (TB85.183, C-F-103589), 180 m. Kangilinnguit, near Grønnedal Hut, 61.23°N, 48.08°W, 15 Aug 1985, T. Borgen (TB85.186, C-F-103527), 350 m, with Salix arctophila in streamside. Narsarsuaq, 61.08°N, 45.26°W, 1 Aug 1991, T. Borgen (TB91.045, C-F-103486), 100 m, with Salix glauca. Narsarsuaq, 61.17°N, 45.41°W, 17 Aug 2015, H. Knudsen (HK15.078, C-F-8231), 60 m, with Dryas sp. along pathside. Paamiut, 62.01°N, 49.4°W, 12 Aug 1984, T. Borgen (TB84.114, C-F-103536), 10 m, with Salix glauca and Salix herbacea. W-Greenland: Kangerlussuaq, airport area, 67.02°N, 50.72°W, 10 Aug 1986, T. Borgen (TB86.177, C-F-103563), 30 m, with Salix glauca. Kangerlussuaq, near the inland ice, 67.09°N, 50.25°W, 12 Aug 2000, K. Kalamees (HK00.032, C-F-7881), 200 m, in tundra. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.46°W, 7 Aug 2016, H. Knudsen (HK16.015, C-F-104045), 200 m, with Salix glauca. Kangerlussuaq, Sandflugtsdalen, c. 15 km E of Base, 67.04°N, 50.53°W, 7 Aug 2016, T. Borgen (TB16.076, C-F-104293), 50 m, with Salix glauca. Kangerlussuaq, Store Saltsø, 66.98°N, 50.6°W, 8 Aug 1986, T. Borgen (TB86.159, C-F-5087), 200 m, with Salix glauca. N-Greenland: Amdrup Land, 80.81°N, 17.32°W, 19 Jul 1993, B. Fredskild (s.n., C-F-7017), 225 m, with Salix arctica in tundra. Blåsø, Kronprins Christians Land, 79.62°N, 23.33°W, 4 Aug 1987, C. Bay (s.n., C-F-6994), 100 m. Prinsesse Dagmars Halvø, Knuths Fjeld, 81.58°N, 16.77°W, 6 Aug 1986, C. Bay (s.n., C-F-4216), 15 m. Zackenberg, at the S bank of Kærelv, 74.5°N, 21°W, 27 Jul 1999, T. Borgen (TB99.114, C-F-119746), 50 m, with Dryas sp. and Salix arctica in scrubland. Zackenberg, in the new delta, 74.5°N, 21°W, 22 Aug 1999, T. Borgen (TB99.411, C-F-119748), 20 m, with Salix arctica in scrubland. Zackenberg, just N of Gadekæret, 74.5°N, 21°W, 5 Aug 1999, T. Borgen (TB99.219, C-F-119752), 20 m, with Dryas sp. and Salix arctica in scrubland. Zackenberg, S of E part of airstrip, 74.5°N, 21°W, 12 Aug 2006, T. Borgen (TB06.159, C-F-119774), 30 m, with Salix arctica in snowbed. Zackenberg, Zackenberg River, 74.5°N, 21°W, 23 Aug 2006, T. Borgen (TB06.263, C-F-119776), 20 m, with Salix arctica in riverbed. E-Greenland: Jameson Land, Constable Pynt, camp N of Katedralen, S of Ugleelv, 70.9°N, 22.92°W, 25 Jul 1989, J.H. Petersen (JHP 89.259, C-F-2561), 170 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 12 Aug 2017, T. Borgen (TB17C.118, C-F-106782), 40 m, with Bistorta vivipara and Salix arctica. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76 22.65°W, 4 Aug 2017, T. Borgen (TB17C.037, C-F-106773), 40 m, with Salix sp. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 12 Aug 2017, H. Knudsen (HK17.265B, C-F-105171), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 7 Aug 2017, H. Knudsen (HK17.147, C-F-105049), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 12 Aug 2017, H. Knudsen (HK17.265A, C-F-105170), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 6 Aug 2017, H. Knudsen (HK17.127, C-F-105028), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.77°N, 22.67°W, 5 Aug 2017, S.A. Elborne (SAE-2017.103-GR, C-F-106761), 40 m, with Arctostaphylos alpina. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.77°N, 22.73°W, 11 Aug 2017, S.A. Elborne (SAE-2017.219-GR, C-F-106769), 40 m, with Salix arctica at riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv, Harris fjeld, 70.75°N, 22.68°W, 31 Jul 2017, T. Borgen (TB17C.006, C-F-106770), 100 m, with Dryas sp. in heathland. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv, Harris fjeld, 70.75°N, 22.68°W, 3 Aug 2017, H. Knudsen (HK17.070, C-F-1049599, 100 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Gåseelv valley, north side, 70.76°N, 22.69°W, 4 Aug 2017, H. Knudsen (HK17.088, C-F-104984), 160 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 10 Aug 2017, T. Borgen (TB17C.094, C-F-106780), 200 m, with Salix arctica in snowbed. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, T. Borgen (TB17C.030, C-F-106772), 200 m, with Salix arctica. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, H. Knudsen (HK17.043, C-F-104932), 200 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, H. Knudsen (HK17.045, C-F-104934), 200 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, H. Knudsen (HK17.052, C-F-104941), 200 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, H. Knudsen (HK17.056, C-F-104945), 200 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.71°N, 22.68°W, 10 Aug 2017, S.A. Elborne (SAE-2017.186-GR, C-F-106765), 200 m, with Salix arctica along streamside. Jameson Land, Nerlerit Inaat/Constable Pynt, middle of Hareelv valley, N side, 70.71°N, 22.73°W, 10 Aug 2017, H. Knudsen (HK17.203, C-F-105108), 320 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, T. Borgen (TB17C.010, C-F-106771), 180 m, with Salix arctica and Bistorta vivipara. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 13 Aug 2017, H. Knudsen (HK17.282, C-F-105189), 180 m.

Distribution

Hebeloma dunense is a common and widespread Hebeloma distributed throughout Mediterranean, Temperate, Boreal, Arctic and Alpine areas. It has been recorded in arctic and alpine areas of North America, Europe and Asia (Russia) (Beker et al. 2016). It has one of the most northern records for a Hebeloma at 81.58° in Greenland (Beker et al. 2016). It appears to be one of the most common and widespread of all Hebeloma species in arctic or alpine regions. Circumpolar, Temperate, Boreal, Subarctic and Arctic-Alpine.

Habitat and ecology

Forty-two collections and one of the five most often collected species in Greenland with 11% of the collections. Most are with Salix arctica (10), S. glauca (6), S. herbacea (2), S. arctophila (1) or unspecified Salix in more or less calcareous habitats. The collection from Paamiut was from a man-made area, in this otherwise acid soil locality. Four collections were recorded with Dryas integrifolia and D. octopetala and one with Arctostaphylos alpina (L.) Spreng., although it is possible that some Salix was present. Arctostaphylos alpina is known as a likely mycorrhizal partner for Hebeloma, and has been recorded as the only possible mycorrhizal partner on several occasions (see for example Grilli et al. 2020). In the Rocky Mountains, Hebeloma dunense was recorded as mycorrhizal with S. arctica, S. planifolia and S. reticulata (Cripps et al. 2019). Beker et al. (2016) found the same pattern for hosts; practically all collections were connected to Salix or Populus (Salicaceae), and a few with Dryas in arctic areas. In Beker et al. (2018), reporting on collections from Svalbard, H. dunense was recorded with Salix 91% of the time, with Dryas 16%, with Bistorta 7% (note that more than one possible host was often recorded).

Hebeloma excedens (Peck) Sacc.; Syll. fung. (Abellini) 5: 806, 1887.

Fig. 11

Macroscopic description

Cap 1.0–4.0 cm in diameter, shallowly convex, campanulate, then almost applanate, broadly umbonate or not, viscid or greasy, with hygrophanous spots, cinnamon to orange-brown or dark brick in center and pale brown on most of the cap, almost unicolored, with or without velar remnants at margin, or with whitish rim, margin originally described as extending beyond the lamellae, thin-fleshed, universal veil sometimes visible on margin edge, partial veil present. Lamellae sinuate, subdecurrent, narrow, becoming broader and eroded, 3.5–5.5 mm broad, without droplets, very pale, cream with pinkish buff tint, number of lamellae {L} 36–48. Stem 1.5–5.0 × 0.2–0.4 cm, equal, slightly curved, pale cream, silky, pruinose above ring zone, dingier to dark brown below, but still pale with golden brown fibrils in zones, blackening towards base, tough, rubbery. Context whitish in cap and stem apex and yellowish brown in lower stem down to blackish at base. Smell raphanoid, rarely odorless. Spore deposit brownish olive.

Figure 11. 

Hebeloma excedens A TB85.238, photograph T. Borgen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of TB85.238 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores ellipsoid, a few slightly ovoid, not papillate, 8.5–10.5 × 5–6 µm, ave. Q 1.5–2.0, very weakly ornamented (O1 O2), perispore not noticeably loosening (P0), indistinctly dextrinoid (D0 D1), pale yellow, rarely yellow brown, ± guttulate. Basidia 20–33 × 6–8 µm, ave. Q = 3.2–4, clavate, mostly four-spored. Cheilocystidia usually lageniform or ventricose, sometimes cylindrical, occasionally geniculate or septate, subcapitate, on ave. 30–55 × 4–6 (apex) × 4–5 (middle) × 7–9 (base) µm, ratios A/M = 0.96–1.23, A/B = 0.60–0.71, B/M = 1.60–1.82. Epicutis an ixocutis, up to 90 µm thick (measured from exsiccata), ixocutis maximum hyphae width up to 6 µm, hyphae rarely encrusted, shape of trama elements beneath subcutis ellipsoid. Caulocystidia similar to cheilocystidia, but usually larger.

Collections examined

S-Greenland: Paamiut, 62.01°N, 49.4°W, 23 Aug 1985, T. Borgen (TB85.238, C-F-5073), 10 m, with Salix glauca. W-Greenland: Kangerlussuaq near the Ice cap, 67.10°N, 50.23°W, 12 Aug 2000, A-M. Larsen, T. Borgen (TB00.086, C-F-103517), 40 m, with Salix glauca in a copse. Sisimiut, 1 km N of the village, 66.94°N, 53.67°W, 19 Aug 2000, E. Ohenoja (EO19.8.00.20, OULU F050653), 0 m, in heathland.

Distribution

Known from three localities in southwestern Greenland. Originally described from New York State under Pinus and widespread across North America (Cripps et al. 2019). Similar to H. mesophaeum and therefore likely to be confused and overlooked. Cripps et al. also describe recent records from alpine Rocky Mountains in Colorado and Montana.

Habitat and ecology

Three collections, two of them with Salix glauca. In the Rocky Mountains, S. planifolia was the dominant host (Cripps et al. 2019). Two of the localities are on acid soil.

Hebeloma fuscatum Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 133, 2016.

Fig. 12

Macroscopic description

Cap 0.7–2.5 cm in diameter, convex to umbonate, margin smooth, tacky when moist, not hygrophanous, uniformly colored or more often bicolored, at center sepia to fuscous or dark brick, sometimes with a thin tomentum, at margin dark olive buff to cinnamon or umber; sometimes with remains of universal veil, partial veil present. Lamellae yellowish ochre then brown, emarginate, maximum depth 4 mm, number of lamellae {L} 24–32, droplets absent, white fimbriate edge usually present, but weak. Stem 0.8–7.0 × 0.15–0.5 {median} cm, whitish or pale grayish then browner to gray brown, not darker towards the base, cylindrical, stem Q 4–13, fibrillose, pruinose at apex. Context firm, stem interior stuffed, later hollow, flesh usually discoloring from base. Smell usually raphanoid but sometimes without smell; taste not recorded. Spore deposit color not recorded.

Figure 12. 

Hebeloma fuscatum A SAE-2016.072, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2016.072 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, limoniform, occasionally ovoid, papillate, on ave. 12.5–13.5 × 7.0–7.5 µm, ave. Q = 1.6–1.9, brown, guttulate, almost smooth to weakly ornamented (O1 O2), perispore not or hardly loosening (P0 (P1)), weakly to rather strongly dextrinoid (D2 D3). Basidia 27–33(-36) × 8–9 µm, ave. Q = 3.0–4.1, mostly four-spored. Cheilocystidia usually lageniform or ventricose, occasionally cylindrical, occasionally characteristically with an apical, basal or median thickening, on ave. 41–51 × 4–7 (apex) × 4.5–6 (middle) × 8–13 (base) µm, ratios A/M = 0.9–1.13, A/B = 0.48–0.67, B/M = 1.75–1.97. Epicutis an ixocutis of 30 µm thickness (measured from exsiccata), maximum hyphae width 5–6 µm, sometimes encrusted, shape of trama elements beneath subcutis sausage-shaped and up to 19 µm wide. Caulocystidia similar to cheilocystidia, but less ventricose and very fragile, up to 75 µm long.

Collections examined

S-Greenland: Paamiut, Churchyard, 62°N, 49.67°W, 26 Jul 1985, D. Boertmann (DB 85-21, C-F-119783), 25 m, with Salix glauca. W-Greenland: Kangerlussuaq, SE of Ravneklippen, 67.00°N, 50.67°W, 29 Aug 2018, T. Borgen (TB18.243, C-F-112530), 200 m, with Salix sp. in fen. Sisimiut, Præstefjeld, 66.96°N, 53.74°W, 17 Aug 2016, S.A. Elborne (SAE-2016.072-GR, C-F-106737), 300 m, with Salix herbacea and Bistorta vivipara. Upernavik, 72.79°N, 56.14°W, 18 Aug 2012, D. Boertmann (DB 12.047, C-F-115623), 0 m, in churchyard. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, around the airport, 70.74°N, 22.64°W, 31 Jul 2017, H. Knudsen (HK17.009A, C-F-104897), 50 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.77°N, 22.72°W, 11 Aug 2017, S.A. Elborne (SAE-2017.215-GR, C-F-106768), 40 m, with Salix arctica along riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, Gåseelv valley, north side, 70.76°N, 22.69°W, 4 Aug 2017, H. Knudsen (HK17.091, C-F-104987), 160 m, with Salix sp. in tundra. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 13 Aug 2017, T. Borgen (TB17C.129, C-F-106783), 180 m, with Betula and Salix in heathland.

Distribution

Recently described and still only recorded from a few alpine and arctic areas in Europe and arctic Canada (Beker et al. 2016). The Greenland collections are from the Low Arctic zone and High Arctic zone, but the species is rare and scattered. Circumpolar, arctic-alpine.

Habitat and ecology

Eight collections, six with Salix glauca, S. arctica and S. herbacea, two with undetermined Salix sp. The presence of Bistorta and Betula are mentioned, each on one occasion. Soil conditions are variable, but mostly calcareous. Salix was the only host mentioned by Beker et al. (2016). Some recent records from subalpine woodlands in central Europe suggest it may also associate with conifers (Grilli et al. 2020).

Hebeloma grandisporum Beker, U. Eberh. & A. Ronikier; Eberhardt, Ronikier, Schütz & Beker, Mycologia 107(6): 1293, 2015.

Fig. 13

Macroscopic description

Cap up to 1.0 cm in diameter, convex to umbonate, margin usually smooth, but can be crenulate, becoming upturned with age, tacky when moist, with slight spotting, not hygrophanous, uniformly colored or bicolored, at center clay buff or pale yellowish brown or cinnamon, at margin paler, universal veil absent, partial veil present. Lamellae clay color, emarginate to adnate, maximum depth not recorded, number of lamellae {L}18–28; droplets absent, white fimbriate edge indistinct. Stem 1.0–2.0 × 0.2–0.3 cm, ochre-brown, paler in apex, cylindrical, stem Q 6.0–8.5, fibrillose, pruinose at apex. Context firm, stem interior stuffed, stem flesh not discoloring from base. Smell weakly raphanoid or insignificant. Taste not recorded. Spore deposit not recorded.

Figure 13. 

Hebeloma grandisporum A HK17.101, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK17.101 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid or limoniform, very strongly papillate, on ave. 14–16 × 8.5–9.5 µm, ave. Q = 1.6–1.8, pale brown to yellow brown, weakly guttulate, almost smooth to weakly ornamented (O1 O2), perispore not loosening (P0), distinctly to rather strongly dextrinoid (D2 D3). Basidia 23–44 × 6–10 µm, ave. Q = 3.1–4.3, characteristically 2-spored. Cheilocystidia lageniform or ventricose, occasionally clavate-ventricose, characteristically geniculate and septate, on ave. 40–70 × 5.5–6.5 (apex) × 4.5–5.5 (middle) × 8–10.5 (base) µm, ratios A/M = 1.02–1.44, A/B = 0.53–0.75, B/M = 1.48–2.03. Epicutis an ixocutis, up to 130 µm thick (measured from exsiccata), maximum hyphae width 6 µm, ixocutis hyphae sometimes encrusted, shape of trama elements beneath subcutis isodiametric. Caulocystidia similar to cheilocystidia, up to 120 µm long.

Collections examined

N-Greenland: Zackenberg, Sydkæret, 74.50°N, 20.75°W, 19 Aug 1999, T. Borgen (TB99.376, C-F-104295), 30 m, with Salix arctica. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, west side of Nathorst Fjeld, 70.76°N, 22.64°W, 5 Aug 2017, H. Knudsen (HK17.101, C-F-104997), 40 m, with Salix sp. in tundra.

Distribution

Recently described from the southern Carpathians in Romania from a single collection. The two Greenland collections are the first recorded since the type has been published. Both are from the High Arctic zone in Greenland at 70° and 74°N, and it is thus in the northernmost group among the 28 Greenland species. The records are the first from North America and the first outside Europe.

Habitat and ecology

Only two records, both most likely with Salix arctica and both on calcareous soil. The only previous collection, the type, grew with S. retusa L. at 2270 m a.s.l. in the Carpathians (Eberhardt et al. 2015a). Shiryaev et al. (2018) reported from Zmitrovich and Ezhov (2015) the presence of Hebeloma gigaspermum Gröger & Zschiesch. from Franz Josefs Land (Russia). According to Beker et al. (2016), H. gigaspermum is most likely a synonym of H. nauseosum Sacc. Since neither H. nauseosum nor any other species of H. sect. Sacchariolentia occurs in arctic areas, it may be that the large spores and the occurrence in the High Arctic zone rather point to H. grandisporum.

Notes

Hebeloma grandisporum is one of the most easily recognized among the arctic-alpine Hebeloma species by the small basidiomes, the large spores, the relatively few, distant lamellae and large, 2-spored basidia. To date, it is the only Hebeloma, of which we are aware, that has consistently 2-spored basidia.

Hebeloma hygrophilum Poumarat & Corriol; Beker, Eberhardt, & Vesterholt, Fungi Europ. (Alassio) 14: 138, 2016.

Fig. 14

Macroscopic description

Cap 0.6–3.0 cm in diameter, convex, occasionally umbonate, margin smooth, tacky when moist, not hygrophanous, uniformly colored or bicolored, at center red brown, dark brick, at margin clay-buff, sometimes with whitish fibrils, remains of universal veil variably present, partial veil present. Lamellae at first whitish or pale orange brown, becoming pale cocoa brown, attachment adnate to emarginate, maximum depth not recorded, number of lamellae {L} 23–32; droplets absent, white fimbriate edge usually present, but weak. Stem 2.0–4.3(–5.0) × 0.1–0.45(–0.7) cm, at first whitish, becoming bright orange brown to dirty brown, darker brown towards the base, cylindrical, stem Q (7.1–)10.1–25.8(–35), fibrillose, pruinose to floccose at apex. Context firm, stem interior stuffed, stem flesh discoloring from base. Smell raphanoid, sometimes weakly. Taste mild, raphanoid, later bitter. Spore deposit not recorded.

Figure 14. 

Hebeloma hygrophilum A HK16.195, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK16.195 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores shape amygdaloid, fusoid or limoniform, papillate, on ave. 11–13 × 6.0–7.0 µm, ave. Q = 1.7–2.0, brown, guttulate, sometimes weakly, weakly to distinctly ornamented ((O1) O2 (O3)), perispore not or somewhat loosening, (P0 P1), distinctly to rather strongly dextrinoid (D2 D3). Basidia 27–32 × 7–9 µm, ave. Q = 3.2–4.2, mostly four-spored. Cheilocystidia lageniform or ventricose, occasionally cylindrical, occasionally with characteristic apical or median wall thickening, geniculate or septate (sometimes clamped), 42–64 × 4.5–5.5 (apex) × 4–5 (middle) × 7–11.5 µm, ratios A/M = 0.89–1.24, A/B = 0.36–0.71, B/M = 1.57–2.52. Epicutis an ixocutis, thickness up to 100–130 µm (measured from exsiccata), maximum hyphae width up to 6–7 µm, ixocutis hyphae sometimes encrusted, trama elements beneath subcutis ellipsoid, sausage-shaped, sometimes cylindrical up to 20 µm wide. Caulocystidia cylindrical to ventricose, multi-septate up to 90 µm long.

Collections examined

S-Greenland: E of Tasiusaq, 61.15°N, 45.60°W, 20 Aug 1993, E. Rald (ER 93.519, C-F-105494), 10 m, in meadow. S of Tasiusaq, 61.13°N, 45.62°W, 23 Aug 1993, E. Rald (ER 93.425, C-F-104549), 0 m. Paamiut, Taartoq/Mørke Fiord, 62.01°N, 49.26°W, 29 Aug 1998, T. Borgen (TB98.234, C-F-103511), 5 m, with Salix glauca in copse. Narsarsuaq, north of Tasiusaq, 60.199186°N, 44.80696°W, 15 Aug 2019, T. Borgen (TB19.052, C-F-137115), 100 m, with Salix glauca in moss on streamside. W-Greenland: Kangerlussuaq, east of Ravneklippen, 67.01°N, 50.66°W, 24 Aug 2016, S.A. Elborne (SAE-2016.168-GR, C-F-106746), 120 m, with Salix glauca along lakeside copse. Kangerlussuaq, Hassells Fjeld, Kløftsøerne, 67.01°N, 50.71°W, 28 Aug 2018, H. Knudsen (HK18.390A, C-F-111118), 300 m, with Salix glauca in bog. Kangerlussuaq, Kløftsøerne, 67°N, 50.71°W, 20 Aug 2016, S.A. Elborne (SAE-2016.105-GR, C-F-106741), 300 m, with Betula nana and Bistorta vivipara along lakeside. Kangerlussuaq, Kløftsøerne, 67.03°N, 50.68°W, 20 Aug 2016, S.A. Elborne (SAE-2016.116-GR, C-F-106742), 300 m, with Salix glauca in copse. Kangerlussuaq, Kløftsøerne, 67.03°N, 50.67°W, 10 Aug 2016, H. Knudsen (HK16.064, C-F-104093), 500 m, in bog. Kangerlussuaq, Kløftsøerne, 67.01°N, 50.71°W, 28 Aug 2018, T. Borgen (TB18.236, C-F-112528), 300 m, with Salix glauca in copse. Kangerlussuaq, N slope towards Lake Ferguson, 66.95°N, 50.72°W, 29 Aug 2018, S.A. Elborne (SAE-2018.429-GR, C-F-115622), 548 m, with Salix arctophila along lakeside. Sisimiut, camping area north of town, 66.94°N, 53.67°W, 20 Aug 2000, S.A. Elborne (SAE-2000.148-GR, C-F-108600), 0 m, with Salix arctophila in bog. Sisimiut, near airport, 66.95°N, 53.67°W, 14 Aug 2016, S.A. Elborne (SAE-2016.005-GR, C-F-106735), 10 m, with Salix sp. in bog. Sisimiut, north of Alanngorsuaq, 66.95°N, 53.55°W, 15 Aug 2016, S.A. Elborne (SAE-2016.022-GR, C-F-106736), 30 m, with Salix sp. in bog. In valley S of Sisimiut behind the dump, 66.93°N, 53.67°W, 18 Aug 2016, H. Knudsen (HK16.195, C-F-108446), 25 m.

Distribution

Found a number of times in southwestern Greenland. Recently described from subalpine areas in the Pyrenees (France) and known from scattered lowland and montane localities in much of Europe. The northernmost locality is from the Boreal zone in Finland (Rovaniemi) at 66.50°N (Beker et al. 2016), which corresponds well in altitude with Kangerlussuaq and Sisimiut (67°N), but in Greenland these areas are Low Arctic. Hebeloma hygrophilum was recently recorded from alpine North America (Rocky Mountains, Cripps et al. 2019). Circumpolar, arctic-alpine, boreal zone.

Habitat and ecology

Fifteen collections, ten with Salix glauca, S. arctophila or unknown Salix. One collection with Betula nana. Most collections grew in moist habitats often among Sphagnum or the moss Paludella squarrosa (Hedw.) Brid. The same type of boggy localities with Salix planifolia were reported by Cripps et al. (2019) in the Rocky Mountains and by Beker et al. (2016) from Europe, where Salix aurita, S. atrocinerea and possibly more species of Salix act as hosts.

Hebeloma marginatulum (J. Favre) Bruchet; Bull. mens. Soc. linn. Lyon 39(6(Suppl.)): 43, 1970.

Fig. 15

Macroscopic description

Cap 1.1–4.7 cm in diameter, convex to umbonate, occasionally papillate, margin smooth, tacky when moist, sometimes hygrophanous, uniformly colored or variably bicolored, at center ochraceous or dark olive buff to brownish olive or umber to sepia to fuscous or dark brick, at margin cream to grayish or pinkish buff to ochraceous or dark olive buff to umber, sometimes very thin; with remains of universal veil, partial veil present. Lamellae initially very pale clay, later clay, emarginate, maximum depth 3–8 mm, number of lamellae {L} 32–45, droplets absent, white fimbriate edge usually weakly present. Stem 1.4–4.5(–6.5) × 0.3–0.7(–0.8) cm, pale sordid ochraceous downwards, cylindrical to slightly clavate, fibrillose, whitish pruinose to floccose at apex. Context watery gray brown in cap, in stem lighter, firm, stem interior stuffed, later hollow, occasionally with superior wick, stem flesh usually discoloring from base. Smell usually raphanoid, but sometimes no smell detected. Taste bitter. Spore deposit clay buff to dark olive buff to grayish brown to brownish olive or umber.

Figure 15. 

Hebeloma marginatulum A HK16.082, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK16.082 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores shape ellipsoid, occasionally amygdaloid or ovoid, on ave. 10.0–13.0 × 5.5–7.5 µm, ave. Q = 1.6–1.9, grayish yellow, rarely guttulate, almost smooth (O1 (O2)), perispore not loosening (P0), not or indistinctly dextrinoid (D0 D1). Basidia (28–)30–34(–37) × 7–9 µm, ave. Q = 4–4.5, mostly four-spored. Cheilocystidia lageniform, ventricose or occasionally cylindrical or clavate, occasionally with characteristic apical thickening, bifurcate, geniculate and septate (sometimes clamped), on ave. 44–69 × 5–7 (apex) × 4.5–5 (middle) × 7.5–10.5 (base) µm, ratios A/M = 1.1–1.4, A/B = 0.53–0.81, B/M = 1.55–2.33. Epicutis an ixocutis, 40–100 µm thick (measured from exsiccata), maximum hyphae width 5–6 µm, variably encrusted, trama elements beneath subcutis ellipsoid, sausage-shaped, occasionally pyriform up to 20 µm wide. Caulocystidia similar to cheilocystidia, but many multi-septate up to 150 µm long.

Collections examined

S-Greenland: Alluitsoq, 60.32°N, 45.27°W, 21 Jul 2003, H.K.J. Beker (HJB10739), 0 m, with Betula sp. and Salix sp. in scrubland. Alluitsoq, 60.32°N, 45.27°W, 21 Jul 2003, H.K.J. Beker (HJB 10742), 0 m, with Betula sp. and Salix sp. in scrubland. Ivittuut, 61.2°N, 48.17°W, 16 Aug 1991, T. Borgen (TB91.198, C-F-103489), 75 m, with Salix glauca in copse. Kangilinnguit, bottom of Laksebund, 61.25°N, 48.08°W, 21 Aug 2018, H. Knudsen (HK18.288, C-F-111113), 100 m, in tundra. Nanortalik municipality, Qinngua valley, 60.14°N, 45°W, 22 Jul 2003, H.K.J. Beker (HJB 10730), 100 m, with Betula pubescens and Salix glauca in woodland. Nanortalik municipality, Qinngua valley, 60.14°N, 45°W, 22 Jul 2003, H.K.J. Beker (HJB 10732), 100 m, with Betula pubescens and Salix glauca in woodland. Narsaq, 60.91°N, 46.05°W, 13 Aug 1993, E. Rald (ER 93.320, C-F-104552), 20 m, with Salix glauca in heathland. Narsaq, 60.91°N, 46.05°W, 2 Aug 1993, E. Rald (ER 93.111, C-F-104312), 20 m, with Salix glauca in heathland. Narsaq, 60.91°N, 46.05°W, 2 Aug 1993, E. Rald (ER 93.112, C-F-106421), 20 m. Narsarsuaq, 61.17°N, 45.42°W, 7 Aug 1985, T. Borgen (TB85.036, C-F-5085), 600 m, with Salix herbacea in snowbed. NE of Nunatoq, 60.27°N, 44.54°W, 22 Aug 1993, E. Rald (ER 93.589, C-F-104554), 0 m. N of Tasiusaq, across the fjord from Narsarsuaq, 61.17°N, 45.61°W, 5 Aug 1992, E. Rald (ER 92.109, C-F-104304), 150 m. Paamiut, 62.01°N, 49.4°W, 20 Aug 1993, T. Borgen (TB93.139, C-F-103495), 50 m, with Salix herbacea in snowbed. Paamiut, 62.01°N, 49.4°W, 23 Aug 1992, T. Borgen (TB92.027, C-F-103493), 10 m, with Salix arctophila and Salix herbacea in fens. Paamiut, 62.01°N, 49.4°W, 23 Aug 1992, T. Borgen (TB92.028, C-F-103492), 10 m, with Salix arctophila and Salix herbacea in tundra. Paamiut, 62.01°N, 49.4°W, 8 Aug 1981, T. Borgen (TB81.109, C-F-103553), 10 m, with Salix herbacea. Paamiut, 61.99°N, 49.66°W, 5 Sep 1986, T. Borgen (TB86.299, C-F-104300), 25 m. Paamiut, 61.99°N, 49.66°W, 4 Aug 1993, E. Rald (ER 93.181, C-F-104314), 25 m, with Salix glauca in heathland. Paamiut, 62°N, 49.4°W, 22 Aug 1986, T. Borgen (TB86.247, C-F-103467), 20 m, with Salix herbacea and Bistorta vivipara. Paamiut Cemetery, 62.01°N, 49.4°W, 19 Aug 1984, T. Borgen (TB84.151, C-F-103538), 10 m, with Salix arctophila. Paamiut, Kangerluarsuk S, 62.28°N, 49.58°W, 31 Aug 1995, B. Knudsen (TB95.068, C-F-103505), 150 m. Paamiut, Kangilineq/Kvaneøen, 61.95°N, 49.47°W, 20 Aug 2008, T. Borgen (TB08.146, C-F-106750), 30 m, with Salix glauca. Qassiarsuk, Tasiusaq, 61.15°N, 45.52°W, 9 Aug 1992, E. Rald (ER 92.181, C-F-104306), 25 m. Qassiarsuk, Tasiusaq, 61.15°N, 45.52°W, 9 Aug 1992, E. Rald (ER 92.180, C-F-104305), 25 m. Tasiusaq, 61.14°N, 45.63°W, 28 Jul 1993, E. Rald (ER 93.021, C-F-104319), 20 m, with Salix glauca in heathland. W-Greenland: Disko, Fortune Bay, 69.31°N, 53.88°W, 2 Aug 1986, T. Borgen (TB86.119, C-F-103566), 20 m. Qeqertarsuaq/Disko, Godhavn, 69.24°N, 53.54°W, 28 Jul 1986, T. Borgen (TB86.060, C-F-6922), 0 m. Disko, Qeqertarsuaq, 69.25°N, 53.55°W, 27 Jul 1986, T. Borgen (TB86.072, C-F-5090), 0 m. Kangerluarsunguaq/Kobbefjord, just south of the field station, 64.14°N, 51.39°W, 11 Aug 2009, T. Borgen (TB09K017, C-F-106753), 20 m, with Salix herbacea in snowbed. Kangerlussuaq, NE facing slopes along Lake Ferguson, 66.10°N, 50.61°W, 12 Aug 2016, H. Knudsen (HK16.082, C-F-104111), 300 m. Nuuk, airport area, 64.19°N, 51.67°W, 14 Aug 2008, T. Borgen (TB08.126, C-F-106749), 100 m, with Salix herbacea in snowbed. Sisimiut, from airport and round the mountain, 66.95°N, 53.72°W, 17 Aug 2016, H. Knudsen (HK16.181, C-F-108419), 30 m. Sisimiut, from airport and round the mountain, 66.95°N, 53.72°W, 17 Aug 2016, H. Knudsen (HK16.180, C-F-108418), 30 m. Sisimiut, into the E valley, 66.90°N, 52.86°W, 15 Aug 2016, H. Knudsen (HK16.134, C-F-104164), 0 m, with Salix herbacea and Salix arctica. Sisimiut, south of town, 66.93°N, 53.65°W, 18 Aug 2016, S.A. Elborne (SAE-2016.085-GR, C-F-106738), 20 m, with Salix herbacea in snowbed. N-Greenland: NE of Annekssø, 77.42°N, 21.33°W, 20 Jul 1990, B. Fredskild (BF 90 loc. 5, C-F-5113), 150 m. Stormlandet, N of Depotnæs, 77.6°N, 18.95°W, 20 Aug 1990, B. Fredskild (BF 90 loc. 8, C-F-5147), 20 m. Zackenberg, 74.5°N, 21°W, 14 Aug 2006, T. Borgen (TB06.170, C-F-119778) ,35 m, with Dryas sp. and Salix sp. in scrubland. Zackenberg, 74.5°N, 21°W, 5 Aug 2006, T. Borgen (TB06.090, C-F-119779), 30 m, with Dryas sp. and Salix arctica in grassland. Zackenberg, near Teltdammen, 74.5°N, 21°W, 5 Aug 2006, T. Borgen (TB06.090, C-F-119747), 30 m, with Dryas sp. and Salix arctica in scrubland. Zackenberg, shortly SW of Kamelen, 74.5°N, 21°W, 11 Aug 2006, T. Borgen (TB06.158, C-F-119775), 40 m, with Salix arctica and Bistorta vivipara in grassland. E-Greenland: Jameson Land, Constable Pynt, 70.75°N, 22.67°W, 30 Jul 1988, D. Boertmann (DB GR 88-40, C-F-3453), 2 m, with Salix arctica. Jameson Land, Constable Pynt, delta of Jyllandselv, 70.68°N, 24.08°W, 28 Jul 1988, D. Boertmann (DB GR 88-33, C-F-3448), 10 m, with Salix herbacea. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 7 Aug 2017, H. Knudsen (HK17.149, C-F-105051), 40 m. Kuummiut, Torsukattak, 65.87°N, 37.01°W, 2 Aug 2008, T. Borgen (TB08.035, C-F-101622), 35 m.

Distribution

Hebeloma marginatulum is widespread and, apparently, one of the most common Hebeloma species in Greenland (11.1% of the collections, see Table 3), also common in other parts of North America and present in parts of Europe (Beker et al. 2016; Cripps et al. 2019). It is a truly arctic-alpine species hardly found outside these areas. Arctic-alpine.

Habitat and ecology

Forty-five collections with many hosts. Twenty collections with Salix (S. herbacea 9, S. glauca 6, S. arctophila 3 and S. arctica 2), two with Betula pubescens var. pumila, two with Betula sp. and three with Dryas octopetala and D. integrifolia (as always, other potential hosts may have been nearby). In the Rocky Mountains, it is also common, found with Salix arctica, S. reticulata and S. planifolia (Cripps et al. 2019). Beker et al. (2016) have S. herbacea and S. polaris as the main hosts. Hebeloma marginatulum occurs on a variety of soil types seemingly without specific preferences.

Hebeloma mesophaeum (Pers.) Quél.; Mém. Soc. Émul. Montbéliard, Sér. 2, 5: 128, 1872.

Fig. 16

Macroscopic description

Cap 0.7–6.5 cm in diameter, convex when young, usually becoming umbonate, sometimes papillate, margin sometimes involute when young, occasionally crenulate, often eroded, upturned or radially split when older, tacky when moist, not hygrophanous, usually bicolored, rarely unicolored, at center dark pinkish buff to dark olive buff to grayish brown to umber or brownish olive to sepia to clay-buff or cinnamon or yellowish brown to orange brown or dark brick, at margin cream to pinkish buff to grayish buff or clay-buff to dark olive buff to grayish brown or brownish olive to grayish pink, with remains of universal veil, partial veil present. Lamellae when young pale brown, when older ochre brown to fairly dark brown, adnate to emarginate, sometimes with decurrent tooth, rarely decurrent, maximum depth up to 6.5 mm, number of lamellae {L} 30–48, droplets absent, but occasionally visible with × 10 lens or rarely visible with naked eye, white fimbriate edge usually present, sometimes weak. Stem 1.4–8.0(–9.0) × (0.2–)0.3–0.6(–0.8) cm, whitish then pale sordid gray brown, already when young dark sordid brown at base, when young with brownish tomentose velar remnants downwards, cylindrical, rarely tapering or clavate, stem Q (4.3–)4.8–16.3(–18.8), fibrillose, usually pruinose to floccose at apex. Context firm, stem interior stuffed, later hollow, occasionally with superior wick, stem flesh discoloring from base, sometimes very strongly, rarely absent. Smell usually raphanoid, rarely absent. Taste mild to bitter, sometimes raphanoid. Spore deposit dark olive buff to brownish olive to umber.

Figure 16. 

Hebeloma mesophaeum A HK17.020, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK17.020 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores ellipsoid, occasionally ovoid, on ave. 8.0–10.5 × 4.5–6.0 µm, Q = 1.3–1.9, (but see the notes below) yellow through yellow brown to brown, guttulation variable, almost smooth to weakly ornamented (O1 O2), perispore not or somewhat loosening (P0 P1), indistinctly dextrinoid (D0 D1). Basidia 24–31(–32) × 7–9 µm; ave. Q = 3.2–4, mostly four-spored. Cheilocystidia lageniform, ventricose, occasionally cylindrical or rarely clavate, occasionally with characteristic apical or basal wall thickening, sometimes bifurcate, geniculate or septate (sometimes clamped), on ave. 26–62 × 4–6 (apex) × 3.5–6 (middle) × 6–11 (base) µm, ratios A/M = 0.94–1.25, A/B = 0.45–0.98, B/M = 1.36–2.19. Epicutis an ixocutis, 60–350 µm thick (measured from exsiccata), maximum hyphae width 3–10 µm, encrustation variable, trama elements beneath subcutis angular or isodiametric to ellipsoid or cylindrical to sausage-shaped up to 22 µm wide. Caulocystidia similar to cheilocystidia, but less ventricose, up to 130 µm long.

Collections examined

S-Greenland: Paamiut, 62°N, 49.67°W, 6 Sep 1990, T. Borgen (TB90.086, C-F-76757), 20 m, with Salix glauca. Paamiut, 62.01°N, 49.67°W, 17 Aug 1990, T. Borgen (TB90.040, C-F-119759), 30 m, with Bistorta vivipara. W-Greenland: Kangerlussuaq, 67.01°N, 50.72°W, 2 Aug 2016, T. Borgen (TB16.038, C-F-104301), 50 m, with Salix glauca in tundra. Kangerlussuaq NE, near a glacier, 67.02°N, 50.66°W, 12 Aug 2000, E. Ohenoja (EO12.8.00.1, OULU F050224), 40 m, in heathland. Kangerlussuaq, Sandflugtsdalen, near the ice cap, 67.0578°N, 50.4571°W, 12 Aug 2000, T. Borgen (TB00.088, C-F-137116), 50 m. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.46°W, 12 Aug 2000, T. Borgen (TB00.093, C-F-103521), 50 m, with Salix glauca in dunes. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.46°W, 12 Aug 2000, T. Borgen (TB00.094, C-F-103522), 200 m, with Salix glauca in dunes. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.46°W, 12 Aug 2000, A-M. Larsen, T. Borgen (TB00.091, C-F-103520), 50 m, with Salix glauca in dunes. Kangerlussuaq, Sandflugtsdalen, c. 15 km E of airport, 67.06°N, 50.46°W, 2 Aug 2016, T. Borgen (TB16.040G, C-F-103578), 50 m, with Salix glauca in dunes. N-Greenland: Zackenberg, S of the Station, towards Zackenberg River, 74.5°N, 21°W, 10 Aug 1999, T. Borgen (TB99.264, C-F-104297), 50 m, with Dryas sp. in scrubland. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.020, C-F-104908), 180 m.

Distribution

Hebeloma mesophaeum is widely distributed, but apparently uncommon in Greenland with only 11 records (2.9%). This is in contrast to the frequency in Europe, where it is very common and widely distributed (Beker et al. 2016). From alpine and arctic Europe, it is known from the Alps, Southern Carpathians, Svalbard and Iceland. Outside Europe and Greenland, there are a few records from the Rocky Mountains (Colorado, Cripps et al. 2019) and arctic Canada (Ohenoja and Ohenoja 2010). It is distributed from the Mediterranean area through the Temperate and Boreal zone to the Arctic and Alpine zones, being less common in the colder areas. Circumpolar, arctic-alpine, temperate, boreal and subarctic.

Habitat and ecology

Eleven collections, six of them with Salix glauca, one with Dryas octopetala and D. integrifolia, one with Bistorta, three not reported. One record from the Rocky Mountains was also with S. glauca. The soil conditions were variable. Hebeloma mesophaeum is widespread and very versatile when it comes to hosts, including many deciduous as well as coniferous hosts (Beker et al. 2016).

Notes

In Beker et al. (2016), it was reported that in arctic and alpine areas there is a chance of confusion with H. marginatulum, due to the fact that sometimes H. mesophaeum, growing in such habitats, tends to have larger spores. They reported that all the ‘large-spored’ collections were from Iceland and Svalbard. In Greenland, we have also found collections with larger spores; indeed, nine of the eleven collections discussed here exhibited larger spores in a range from 10.3–11.7 × 6.4–7.1 µm, a similar range to that reported for Svalbard and Iceland. At the time, Beker et al. (2016) did consider creating a variety to address these collections but decided such a course of action was premature and that further study of this variation was required. With regard to the confusion with H. marginatulum, the strongly bicolored cap of H. mesophaeum should normally aid identification.

Hebeloma nigellum Bruchet; Bull. mens. Soc. linn. Lyon 39(6(Suppl.)): 126, 1970.

Fig. 17

Macroscopic description

Cap 0.7–3.4 cm in diameter, convex to umbonate, occasionally papillate, margin involute, tacky when moist, unicolored or usually bicolored, at center umber to dark brick or snuff brown, at margin cream to pinkish buff, occasionally with remains of universal veil, partial veil present. Lamellae at maturity brownish clay, adnate to emarginate, maximum depth 2.5–6 mm, number of lamellae {L} 22–36, droplets absent, white fimbriate edge present, sometimes weakly. Stem 1.4–5.0 × 0.15–0.4 cm, whitish pruinose at apex, initially whitish lengthily fibrillose, downward, sordid brown, cylindrical, stem Q (6.5–)7.5–12.5(–18.7), fibrillose, pruinose to floccose at apex. Context firm, stem interior stuffed later hollow, flesh discoloring from base, sometimes very strongly. Smell usually raphanoid, sometimes none. Taste bitter, raphanoid. Spore deposit umber.

Figure 17. 

Hebeloma nigellum A HK16.033, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of TB85.249 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores mainly amygdaloid, sometimes ellipsoid to ovoid, on ave. 11.0–13.5 × 7.0–7.5 µm, ave. Q = 1.5–1.9, yellow through yellow brown to brown, guttulation variable, almost smooth to slightly ornamented (O1 O2), perispore not or very slightly loosening (P0 (P1)), rather strongly dextrinoid ((D2) D3). Basidia 25–39(–45) × 7–10(–11) µm, ave. Q = 3.1–3.9, mostly four-spored. Cheilocystidia usually lageniform, ventricose, occasionally cylindrical, occasionally with characteristic apical wall thickening, geniculate or septate (sometimes clamped), 44–65 × 4.5–6.5 (apex) × 4–5.5 (middle) × 6.5–11 (base) µm, ratios A/M = 0.92–1.41, A/B = 0.45–0.89, B/M = 1.45–2.3. Epicutis an ixocutis, 40–75 µm thick (measured from exsiccata), maximum hyphae width 5–6.5 µm, sometimes encrusted, trama elements beneath subcutis ellipsoid, polygonal, sausage-shaped up to 15 µm wide. Caulocystidia rather irregular, similar to cheilocystidia, up to 140 µm long.

Collections examined

S-Greenland: Kangilinnguit, bottom of Laksebund, 61.25°N, 48.08°W, 16 Aug 2018, H. Knudsen (HK18.199, C-F-111110), 100 m, with Alnus alnobetulae in scrubland. Nanortalik municipality, Qinngua valley, 60.14°N, 45°W, 6 Aug 1991, T. Borgen (TB91.080, C-F-103490), 250 m, with Salix glauca in copse. Paamiut, 62.01°N, 49.4°W, 31 Aug 1986, T. Borgen (TB86.276, C-F-103572), 10 m. Paamiut, 62.01°N, 49.4°W, 14 Aug 1990, T. Borgen (TB90.035, C-F-103479), 10 m. Paamiut, 62.01°N, 49.4°W, 1 Sep 1990, T. Borgen (TB90.073, C-F-103541), 10 m, with Salix arctophila along riverside. Paamiut, Kangilineq, Kvaneøen, 61.95°N, 49.47°W, 26 Aug 1984, T. Borgen (TB84.183, C-F-103468), 10 m, with Salix arctophila. Paamiut, Kangilineq/Kvaneøen, 61.57°N, 49.28°W, 25 Aug 1985, T. Borgen (TB85.249, C-F-103529), with Salix. Paamiut, Kangilineq/Kvaneøen, 61.99°N, 49.66°W, 26 Aug 1990, T. Borgen (TB90.056, C-F-103542), 15 m, with Salix arctophila in fenland. W-Greenland: Disko, N end of Blæsedalen, 69.5°N, 53.32°W, 25 Jul 1986, T. Borgen (TB86.052, C-F-119739), 300 m, with Salix herbacea in snowbed. Kangerlussuaq, Ammaloortup Nunaa W of Lake Ferguson, 66.99°N, 50.61°W, 8 Aug 2016, H. Knudsen (TB16.086G, C-F-103583), 275 m, with Salix glauca, Betula nana and Sphagnum along streamside. Kangerlussuaq, Kløftsøerne, 67.06°N, 50.68°W, 13 Aug 2016, H. Knudsen (HK16.110, C-F-104140), 500 m, with Salix glauca. Kangerlussuaq, Lake Ferguson, Tasersuatsiaq, 66.97°N, 50.70°W, 22 Aug 2016, S.A. Elborne (SAE-2016.131-GR, C-F-106743), 100 m, with Salix glauca in copse. Kangerlussuaq, NE facing slopes along Lake Ferguson, 66.99°N, 50.61°W, 8 Aug 2016, H. Knudsen (HK16.033, C-F-104063), 300 m, with Salix glauca in riverbed. Kangerlussuaq, outlet of Lake Ferguson, 66.99°N, 50.61°W, 6 Aug 2016, T. Borgen (TB16.060G, C-F-103580), 275 m, with Salix glauca in scrubland. Kangerlussuaq, W Bridge near Ice cap, 67.09°N, 50.23°W, 2 Aug 2016, T. Borgen (TB16.035G, C-F-103577), 50 m, with Salix glauca at lakeside. NW of Nasaassaq, E-valley, E of Sisimiut, 66.93°N, 53.61°W, 18 Aug 2000, E. Horak (ZT9139, ZT9139), 50 m, with Betula nana, Salix glauca and Salix herbacea. Qeqertarsuaq/Disko, Godhavn area, 69.65°N, 53.32°W, 26 Jul 1986, T. Borgen (TB86.065, C-F-119791), 450 m. Sisimiut, 1 km north of the village, 66.94°N, 53.67°W, 19 Aug 2000, E. Ohenoja (EO19.8.00.20, OULU F050653), 0 m, in heathland. Sisimiut, in the E valley, 66.89°N, 52.86°W, 15 Aug 2016, H. Knudsen (HK16.133, C-F-104163), 0 m, with Salix herbacea. Sisimiut, Kællingehætten, 66.93°N, 53.59°W, 16 Aug 2016, H. Knudsen (HK16.165A, C-F-108402), 400 m. E-Greenland: Jameson Land, Constable Pynt, Draba Sibirica Elv, 71.15°N, 23.57°W, 28 Jul 1983, D. Boertmann (DB GR 83-80, C-F-119734), 0 m, with Salix arctica.

Distribution

Hebeloma nigellum is common and widespread in Greenland and present in other parts of North America (Cripps et al. 2019). It is widespread in temperate Europe, but more commonly in arctic-alpine areas (Beker et al. 2016). Circumpolar.

Habitat and ecology

Twenty-one collections, and where the host was specified, 15 were recorded with Salix (S. glauca 8, S. arctophila 3, S. herbacea 3, S. arctica 1), and one recorded with Alnus alnobetulae ssp. crispa. The majority are from riversides, lakesides, fens and snowbeds, but also in humid places with S. arctophila. Most localities are on neutral ground, but it is found in acid localities as well. In the Rocky Mountains, it was recorded with Salix planifolia (Cripps et al. 2019). From lowland Europe Beker et al. 2016 noted S. aurita and S. cinerea as hosts.

Hebeloma oreophilum Beker & U. Eberh.; Eberhardt, Ronikier, Schütz & Beker, Mycologia 107(6): 1295, 2016 (“2015”).

Fig. 18

Macroscopic description

Cap 1.0–3.8 cm in diameter, convex to umbonate, sometimes strongly, margin smooth, often involute when young, tacky when moist, usually not hygrophanous, but we have occasionally seen collections that are, unicolored or variably two-colored, at center dark olive buff to brownish olive to umber to cinnamon or sepia to brick to dark brick to fuscous, sometimes cracked, at margin cream to pinkish buff to clay-pink, sometimes margin very thin, usually pruinose to tomentose, usually with remains of universal veil, partial veil present. Lamellae whitish then pale clay brown, emarginate to broadly adnexed, maximum depth 3–8 mm, number of lamellae {L} 40–48, droplets absent or very small (lens), white fimbriate edge sometimes present. Stem 1.5–7.0 × 0.3–0.65 {median} × (0.3–1.0) {base} cm, at first whitish later brown downwards, apically with whitish fibrillose ring zone, sometimes with indistinct belts, downwards with suggestion of a fibrillose ring, pale sordid brown, pale watery brown, downwards dark brown when rubbed, cylindrical, rarely clavate, stem Q (4.2–)5.5–8.7(–15), pruinose at apex. Context firm, stem interior stuffed, later hollow, stem flesh discoloring from base usually. Smell raphanoid. Taste raphanoid, slightly bitter. Spore deposit brownish olive.

Figure 18. 

Hebeloma oreophilum A SAE-2016.134, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK18.401 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, occasionally ovoid or limoniform, usually weakly papillate, on ave. 11.0–14.0 × 6.5–7.5 µm, ave. Q = 1.6–2.1, yellow brown through brown, guttulation variable, almost smooth to weakly ornamented (O1 O2), perispore not or somewhat loosening (P0 P1), distinctly to rather strongly dextrinoid (D2 D3). Basidia (25–)26–33(–36) × 7–9(–11) µm, ave. Q = 3.3–4.9, mostly four-spored. Cheilocystidia lageniform, ventricose, occasionally cylindrical, occasionally with characteristic apical, median or basal wall thickening, geniculate or septate, 42–57 × 4–6 (apex) × 4–6 (middle) × 8–10 (base) µm, sometimes with yellowish contents, ratios A/M 1.03–1.24, A/B = 0.44–0.67, B/M = 1.57–2.4. Epicutis an ixocutis, 40–70 µm thick (measured from exsiccata), maximum hyphae width 5–7 µm, without encrustations, trama elements beneath subcutis cylindrical to sausage-shaped up to 18 µm wide. Caulocystidia similar to cheilocystidia but less ventricose more cylindrical, often multi-septate, up to 120 µm long.

Collections examined

S-Greenland: Kangilinnguit, 61.14°N, 48.6°W, 20 Aug 1991, T. Borgen (TB91.233, C-F-103487), 25 m, with Alnus alnobetulae. Kangilinnguit at Grønnedal Hut, 61.23°N, 48.08°W, 15 Aug 1985, T. Borgen (TB85.180, C-F-119740), 350 m, with Salix arctophila in Sphagnum. Narsarsuaq, outer part of Hospital Valley, 61.17°N, 45.43°W, 9 Aug 1985, T. Borgen (TB85.061, C-F-103590), 50 m, with Betula pubescens and Salix glauca. Paamiut, 62.01°N, 49.4°W, 12 Aug 1990, T. Borgen (TB90.010, C-F-103558), 25 m, with Salix arctophila and Salix herbacea in snowbed. Paamiut, 62.01°N, 49.4°W, 14 Aug 1990, T. Borgen (TB90.036, C-F-103480), 10 m, with Salix glauca. Paamiut, 62.01°N, 49.4°W, 1 Sep 1986, T. Borgen (TB86.292, C-F-103588), 100 m. Paamiut, 62.01°N, 49.4°W, 5 Aug 1998, T. Borgen (TB98.073, C-F-103509), 35 m, with Salix herbacea in fen. Paamiut, “Peters Fjeld”, 62.01°N, 49.4°W, 31 Aug 1983, T. Borgen (TB83.035, C-F-103472), 10 m, with Salix arctophila in Sphagnum. Paamiut, head of Eqaluit, median part, 62.03°N, 49.25°W, 15 Aug 1998, T. Borgen (TB98.120, C-F-103510), 300 m, with Betula glandulosa and Salix glauca in heathland. Paamiut, Kangilineq /Kvaneøen, 61.95°N, 49.47°W, 6 Sep 1984, T. Borgen (TB84.215, C-F-104298), 20 m, with Salix herbacea and Bistorta vivipara in snowbed. Paamiut, Kangilineq/Kvaneøen, 61.99°N, 49.66°W, 27 Aug 1984, T. Borgen (TB84.184, C-F-103539), 15 m, with Salix glauca. W-Greenland: Kangerlussuaq, Kløftsøerne, 67.03°N, 50.80°W, 31 Jul 2016, T. Borgen (TB16.017G, C-F-103576), 300 m, with Betula nana and Salix glauca, in Sphagnum in scrubland. Kangerlussuaq, Lake Ferguson, Tasersuatsiaq, 66.97°N, 50.70°W, 22 Aug 2016, S.A. Elborne (SAE-2016.134-GR, C-F-106744), 100 m, with Salix glauca in copse. Kangerlussuaq, NE facing slopes along Lake Ferguson, 66.99°N, 50.61°W, 12 Aug 2016, H. Knudsen (HK16.091, C-F-104120), 300 m, in Sphagnum sp. Kangerlussuaq, slopes SW of Lake Ferguson, 66.96°N, 50.69°W, 29 Aug 2018, H. Knudsen (HK18.401, C-F-111120), 380 m, in tundra. N-Greenland: Zackenberg, 74.5°N, 21°W, 17 Aug 2006, T. Borgen (TB06.225, C-F-119772), 20 m, with Salix arctica in scrubland. Zackenberg, Sydkæret, 74.5°N, 21°W, 19 Aug 1999, T. Borgen (TB99.374, C-F-119758), 30 m, with Salix arctica in scrubland. Zackenberg, Sydkæret, 74.5°N, 21°W, 5 Aug 2006, T. Borgen (TB06.098, C-F-119773), 20 m, in fen.

Distribution

Widely distributed and apparently common in Greenland, but never recorded from the East coast (only north east, see habitat). Described recently (Eberhardt et al. 2015a) from an alpine site (1970 m) in Slovakia and still only known from few countries. In Europe, it is recorded from northern Finland, from the Subarctic and Arctic zone and from the High Arctic zone on Svalbard. Outside Europe, it is known from low alpine and alpine sites in the Rocky Mountains and Canada (Beker et al. 2016, Cripps et al. 2019). Circumpolar, arctic-alpine to subarctic.

Habitat and ecology

Eighteen collections, six recorded with Salix glauca, four with S. arctica, three with S. arctophila, two with S. herbacea and one recorded under Alnus alnobetulae ssp. crispa. The absence from the calcareous, well-investigated Jameson Land on the east coast may signal a preference for more acid soil types. In the low alpine Rocky Mountains, Cripps et al. (2019) found it a number of times with Salix planifolia, S. arctica and S. glauca.

Hebeloma pubescens Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 173, 2016.

Fig. 19

Macroscopic description

Cap 1.2–2.4 cm in diameter, convex to umbonate, sometimes papillate, margin smooth, tacky when moist, not hygrophanous, unicolored or variably bicolored, at center grayish brown to yellowish brown or umber, tomentose, usually covered, particularly at the margin, with soft hairs, at margin dark grayish buff, sometimes with remains of universal veil, partial veil present. Lamellae light brown, later slightly darker, emarginate, maximum depth 2.5–5 mm, number of lamellae {L} 25–32, droplets absent, white fimbriate edge weakly present. Stem 1.1–4.6 × 0.2–0.4 cm, whitish pale floccose in apex, downwards lengthily fibrillose, sordid brown or very pale ochraceous, cylindrical, stem Q (3.7–)4.8–8.3(–9.7), fibrillose. Context firm, stem interior stuffed, later hollow, flesh usually discoloring from base. Smell raphanoid, sometimes strongly. Taste mild. Spore deposit brownish olive.

Figure 19. 

Hebeloma pubescens A TB99.194, photograph T. Borgen B distribution of cited collections; C spores ×1600 and D cheilocystidia ×1000 of TB99.194 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores ellipsoid, sometimes ovoid, pale yellow to yellow brown, guttulate, sometimes weakly, on ave. 10.0–12.0 × 6.0–6.5 µm, ave. Q = 1.5–1.8, almost smooth or weakly ornamented (O1 O2), perispore not loosening (P0), indextrinoid (D0). Basidia 28–33(-37) × 8–9 µm, ave. Q = 3.1–4.4, mostly four-spored. Cheilocystidia lageniform or ventricose, occasionally with characteristic basal or median wall thickening, septate, on ave. 38–45 × 4.5–6 (apex) × 4.5–6 (middle) × 8–10.5 (base) µm, ratios A/M = 1.02–1.10, A/B = 0.51–0.73, B/M = 1.52–2.10. Epicutis an ixocutis, 90–100 µm thick (measured from exsiccata), maximum hyphae width 6 µm, sometimes encrusted, trama elements beneath subcutis isodiametric up to 15 µm wide. Caulocystidia similar to cheilocystidia but less ventricose, up to 120 µm long.

Collections examined

W-Greenland: Disko, Kangaarsuk, Fortune Bay, 69.25°N, 53.54°W, 3 Aug 1986, T. Borgen (TB86.128, C-F-5089), 0 m, with Salix sp. N-Greenland: Zackenberg, W of Kærelv, 74.5°N, 21°W, 13 Aug 1999, T. Borgen (TB99.305, C-F-119753), 50 m, with Dryas sp. in scrubland. Zackenberg, W of Zackenberg River, 74.5°N, 21°W, 5 Aug 1999, T. Borgen (TB99.194, C-F-119750), 50 m, with Dryas sp. and Salix arctica in scrubland.

Distribution

Recently described from three records on Svalbard (Beker et al. 2016). The Greenland records are all north of 69° and, together with the type from 78°N, establish this as one of the few agarics, which appear only to occur in the High Arctic zone. The Greenland records are new to North America and the first outside Europe. High Arctic.

Habitat and ecology

Three collections, two with Dryas and one with Salix sp. The collections from Zackenberg were on rich soil. Beker et al. (2016) described it from Svalbard, where the host was Salix polaris.

Hebeloma spetsbergense Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 180, 2016.

Fig. 20

Macroscopic description

Cap 1.0–2.2 cm in diameter, convex to umbonate, sometimes umbilicate, margin smooth, tacky when moist, occasionally hygrophanous, unicolored, sometimes bicolored, at center sepia to fuscous or dark brick, at margin pinkish buff to clay pink to cinnamon, sometimes quite thin margin, without remains of universal veil, partial veil present. Lamellae initially light clay, at maturity slightly more brownish, attachment emarginate, maximum depth 3–5 mm, number of lamellae {L} 18–35, droplets absent, white fimbriate edge sometimes present but weak. Stem (1.5–)1.9–3.1(–3.7) × 0.2–0.3(–0.5) cm, light watery brownish, darker towards base, cylindrical, stem Q (5–)8–12.7(–16.5), fibrillose, usually pruinose at apex. Context firm, stem interior stuffed, later hollow, stem flesh variably discoloring from base. Smell raphanoid sometimes strongly. Taste weakly raphanoid. Spore deposit sepia.

Figure 20. 

Hebeloma spetsbergense A HK16.071, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK16.071 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, occasionally limoniform, guttulation variable, on ave. 12.0–14.5 × 7.5–8.5 µm, ave. Q = 1.5–1.7, yellow brown to brown, almost smooth to weakly ornamented (O1 O2), perispore not loosening (P0), rather strongly dextrinoid (D2 D3). Basidia 27–37(-40) × 9–12 µm, ave. Q = 3.3–3.9, mostly four-spored. Cheilocystidia lageniform, ventricose, occasionally with characteristically median wall thickening, some septate, on ave. 45–60 × 4.5–6 (apex) × 4.5–5 (middle) × 8.5–12 (base) µm, occasionally cystidia with yellow contents, ratios A/M = 0.92–1.25, A/B = 0.43–0.61, B/M = 1.87–2.61. Epicutis an ixocutis, 30–35 µm thick (measured from exsiccata), maximum hyphae width 5 µm, without encrustations, shape of trama elements beneath subcutis sausage-shaped, up to 18 µm wide. Caulocystidia similar to cheilocystidia but generally larger.

Collections examined

W-Greenland: Disko, Fortune Bay, 69.31°N, 53.88°W, 3 Aug 1986, T. Borgen (TB86.121, C-F-103478), 20 m, with Salix glauca in dunes. Qeqertarsuaq/Disko, Godhavn, 69.65°N, 53.32°W, 5 Aug 1986, S.A. Elborne (SAE-86.135-GR, C-F-119733), 0 m, with Salix glauca at lakeside. Kangerlussuaq, just west of Lake Ferguson, 66.99°N, 50.61°W, 6 Aug 2016, T. Borgen (TB16.056G, C-F-103579), 50 m, with Salix glauca and Betula nana in ditch. Kangerlussuaq, Kløftsøerne, 67°N, 50.71°W, 20 Aug 2016, S.A. Elborne (SAE-2016.102-GR, C-F-106740), 270 m, with Betula nana and Bistorta vivipara along lakeside. Kangerlussuaq, Kløftsøerne, 67.03°N, 50.69°W, 19 Aug 2016, H. Knudsen (HK s.n., C-F-108450), 500 m, with Salix sp. and Betula sp. Kangerlussuaq, NE facing slopes along Lake Ferguson, 66.99°N, 50.61°W, 12 Aug 2016, H. Knudsen (HK16.071, C-F-104100), 300 m. N-Greenland: Zackenberg, just N of Zackenberg Hut, 74.5°N, 21°W, 9 Aug 1999, T. Borgen (TB99.256, C-F-119757), 50 m, with Salix arctica, Bistorta vivipara and Sphagnum in scrubland. E-Greenland: Jameson Land, Constable Pynt, Draba Sibirica Elv, 10 km from coast, 71.03°N, 24.23°W, 23 Jul 1983, D. Boertmann (DB GR 83-62, C-F-119801), 50 m, with Salix arctica along riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 12 Aug 2017, T. Borgen (TB17C.113, C-F-106781), 40 m, with Bistorta vivipara in heathland. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 9 Aug 2017, S.A. Elborne (SAE-2017.174-GR, C-F-106764), 40 m, with Salix arctica along riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, S.A. Elborne (SAE-2017.043-GR, C-F-106760), 200 m, with Salix arctica in bog. Jameson Land, Nerlerit Inaat/Constable Pynt, near airstrip, 70.74°N, 22.64°W, 6 Aug 2017, T. Borgen (TB17C.050, C-F-106774), 50 m, with Salix sp. in fen.

Distribution

Recently described from high arctic Svalbard (Beker et al. 2016). The eleven Greenland records indicate that it is quite common in the High Arctic zone in Greenland north of 67°N. Circumpolar, High Arctic.

Habitat and ecology

Twelve collections, four recorded with Salix arctica, four with S. glauca, two with Salix spp., one with Betula nana and one with Bistorta vivipara. Bistorta is often present near collections of mycorrhizal fungi, but only when it was the only possibility was this host recorded. In the Rocky Mountains, Cripps et al. (2019) reported two collections growing with S. glauca and S. arctica. In Greenland, H. spetsbergense is growing both in acid and calcareous habitats, most often in humid localities like bogs, riversides and ditches. The five collections from Svalbard, including the type, are from localities on base-poor ground with S. polaris (Beker et al. 2016).

Hebeloma sect. Denudata (Fr.) Sacc.; Fl. Ital. Crypt. I 15: 691, 1916

Veil absent. Cap uni- or bicolored. Lamellae often exuding small hyaline or colored drops. Cheilocystidia long, swollen in the apical part, constricted in the median part, basal part swollen or not. Spores amygdaloid to limoniform, ornamented, sometimes strongly.

Hebeloma subsect. Crustuliniformia Quadr.; Doc. mycol. 14: 30, 1985 (“1984”)

Cheilocystidia distinctly broadened at apex, base ± cylindrical, wall not thickened. Lamellae edge often with exuded drops.

Hebeloma alpinum (J. Favre) Bruchet; Bull. mens. Soc. linn. Lyon 39(6(Suppl.)): 68, 1970.

Fig. 21

Macroscopic description

Cap 1.7–7.3 cm, convex to umbonate or broadly umbonate; margin smooth, often involute, sometimes crenulate or serrate, tacky when moist, not hygrophanous, almost unicolored, occasionally bicolored, at center cream to pink buff to dark olive buff brown or yellowish brown to brownish olive or umber to sepia, clay buff or cinnamon, margin cream to pink buff or clay buff, sometimes very thin, universal veil absent, partial veil absent. Lamellae whitish, later light gray brown, then sordid brownish, number of lamellae {L} 40–72, emarginate, 0.3–0.9 cm broad, exuded drops usually visible with naked eye, but sometimes absent, with white fimbriate edge. Stem 1.5–5.0 × 0.4–1.2 cm, whitish fimbriate-pruinose in the entire length, later downwards slightly sordid ochraceous, ochre-yellowish or pale brown, base cylindric to clavate, rarely bulbous, occasionally tapering, pruinose to floccose particularly at apex, when fresh with droplets. Trama firm, stem with a stuffed interior, occasionally becoming hollow with age, not discoloring. Smell usually raphanoid, occasionally of cocoa or absent. Taste mild to weakly bitter. Spore deposit dark olive buff, brownish olive to clay buff.

Figure 21. 

Hebeloma alpinum A SAE-2017.006, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2017.006 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid to limoniform, on ave. 9.5–15 × 5.5–8.5 µm, ave. Q = 1.4–2.2, yellow brown to brown, sometimes guttulate, papillate, sometimes very strongly, almost smooth to weakly ornamented (O1 O2 (03)), perispore not or somewhat loosening (P0 P1), indextrinoid to weakly dextrinoid (D0 D1 D2). Basidia 28–40(–45) × 8–12 µm, Q = 3–4.3, mostly four-spored. Cheilocystidia mainly clavate-stipitate or spathulate-stipitate, occasionally slenderly clavate or clavate-lageniform, occasional apically thickening, rostrate, septate or sinuate, on ave. 40–71 × 7–10 (apex) × 3.5–5 (middle) × 3.5–6 (base) µm, ratios A/M = 1.6–2.7, A/B = 1.5–2.7, B/M = 0.9–1.2. Pileipellis an ixocutis, 60–160 µm thick (measured from exsiccata), hyphae 5–6 µm broad, some encrusted; trama elements beneath subcutis cylindrical, ellipsoid, thick sausage-shaped, up to 18 µm wide. Caulocystidia similar to cheilocystidia, up to 120 µm long and 11 µm wide.

Collections examined

S-Greenland: Paamiut, 62.01°N, 49.4°W, 18 Aug 1984, T. Borgen (TB84.148, C-F-103537), 25 m, with Salix herbacea and Salix glauca. Sermiliarsuk, Sioralik, Aasivii, 65.53°N, 48.33°W, 30 Aug 1997, T. Borgen (TB97.153a, C-F-103507), 50 m, with Betula pubescens and Salix glauca in copse. Sermiliarsuk, Sioralik, Aasivii, 65.53°N, 48.33°W, 30 Aug 1997, T. Borgen (TB97.152, C-F-103506), 50 m, with Dryas integrifolia in heathland. W-Greenland: Disko, Qeqertarsuaq, 69.24°N, 53.54°W, 5 Aug 1986, T. Borgen (TB86.141, C-F-103565), 0 m. Disko, Skarvefjeld at Qeqertarsuaq, 69.65°N, 53.32°W, 2 Aug 1986, T. Borgen (TB86.115, C-F-103458), 400 m, with Dryas integrifolia. Kangerlussuaq, airport area, 67.02°N, 50.69°W, 1 Aug 1995, T. Borgen (TB95.004, C-F-103503), 50 m, with Salix glauca and Betula nana in copse. Kangerlussuaq, Hassells Fjeld, Kløftsøerne, 67.01°N, 50.71°W, 28 Aug 2018, H. Knudsen (HK18.390D, C-F-111119), 50 m, with Salix glauca in tundra. Kangerlussuaq, near hotel, 67.02°N, 50.7°W, 7 Aug 1986, T. Borgen (TB86.153, C-F-101230), 50 m, with Salix glauca and Betula nana in tundra. Kobbefjord, NuukBasic, 64.08°N, 51.23°W, 24 Aug 2018, H. Knudsen (HK18.308, C-F-111115), 5 m, in tundra. N-Greenland: Daneborg, 0.5 km E of Airstrip, 74.2°N, 20.1°W, 29 Jul 2006, T. Borgen (TB06.034, C-F-119763), 20 m, with Dryas sp. in heathland. V. Clausen Fjord, 77.52°N, 20.66°W, 13 Aug 1990, B. Fredskild (BF 90 loc. 6, C-F-5180), 0 m. Zackenberg, Aucellabjerg, 74.47°N, 21°W, 9 Aug 2006, T. Borgen (TB06.137, C-F-119766), 160 m, with Dryas sp. and Salix arctica in heathland. Zackenberg, Aucellabjerg, 74.47°N, 21°W, 11 Aug 1999, T. Borgen (TB99.283, C-F-119808), 100 m, with Dryas sp. in heathland. Zackenberg, few 100 m west of Zackenberg River, 74.47°N, 21°W, 3 Aug 1999, T. Borgen (TB99.199, C-F-104294), 50 m, with Dryas sp. in scrubland. Zackenberg, just S of Kamelen, 74.47°N, 21°W, 27 Jul 1999, T. Borgen (TB99.115, C-F-119806), 50 m, with Dryas sp. and Salix arctica at riverside. Zackenberg, just S of Teltdammen, 74.47°N, 21°W, 20 Jul 1999, T. Borgen (TB99.027, C-F-119742), 40 m, with Dryas sp. in scrubland. Zackenberg, just S of Teltdammen, 74.3°N, 21°W, 20 Jul 1999, T. Borgen (TB99.023, C-F-119744), 40 m, with Dryas sp. and Salix sp. in scrubland. Zackenberg, just W of Kærelv, 74.47°N, 21°W, 30 Jul 1999, T. Borgen (TB99.159, C-F-119807), 30 m, with Salix arctica and Bistorta vivipara on solifluction lobe. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, 70.74°N, 22.65°W, 31 Jul 2017, S.A. Elborne (SAE-2017.008-GR, C-F-106758), 10 m, with Dryas sp. and Salix sp. in tundra. Jameson Land, Nerlerit Inaat/Constable Pynt, 70.74°N, 22.67°W, 31 Jul 2017, S.A. Elborne (SAE-2017.006-GR, C-F-106757), 60 m, with Betula nana and Dryas sp. in tundra. Jameson Land, Nerlerit Inaat/Constable Pynt, around the airport, 70.74°N, 22.64°W, 31 Jul 2017, H. Knudsen (HK17.001, C-F-104889), 50 m. Jameson Land, Nerlerit Inaat/Constable Pynt, around the airport, 70.74°N, 22.64°W, 31 Jul 2017, H. Knudsen (HK17.005, C-F-104893), 50 m. Jameson Land, Nerlerit Inaat/Constable Pynt, around the airport, 70.74°N, 22.64°W, 31 Jul 2017, H. Knudsen (HK17.006, C-F-104894), 50 m. Jameson Land, Nerlerit Inaat/Constable Pynt, around the airport, 70.74°N, 22.64°W, 31 Jul 2017, H. Knudsen (HK17.007, C-F-104895), 50 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 8 Aug 2017, T. Borgen (TB17C.089, C-F-106779) ,40 m, with Bistorta vivipara in fenland. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 6 Aug 2017, H. Knudsen (HK17.123, C-F-105024), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 7 Aug 2017, H. Knudsen (HK17.148, C-F-105050), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Gåseelv, Harris Fjeld, 70.75°N, 22.68°W, 3 Aug 2017, H. Knudsen (HK17.062, C-F-104951), 95 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, H. Knudsen (HK17.049, C-F-104938), 200 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 2 Aug 2017, H. Knudsen (HK17.054, C-F-104943), 200 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.7°N, 22.68°W, 10 Aug 2017, S.A. Elborne (SAE-2017.188-GR, C-F-106766), 100 m, with Salix arctica in bog. Jameson Land, Nerlerit Inaat/Constable Pynt, Mt. Harris, 70.75°N, 22.68°W, 6 Aug 2017, T. Borgen (TB17C.053, C-F-106775), 100 m, with Dryas sp. and Bistorta vivipara in heathland. Jameson Land, Nerlerit Inaat/Constable Pynt, north of Primulaelv, 70.75°N, 22.66°W, 1 Aug 2017, S.A. Elborne (SAE-2017.014-GR, C-F-106759), 10 m, with Dryas sp. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 13 Aug 2017, T. Borgen (TB17C.134, C-F-106784), 180 m, with Bistorta vivipara. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 13 Aug 2017, H. Knudsen (HK17.278, C-F-105185), 180 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.023, C-F-104912), 180 m, in tundra.

Distribution

Hebeloma alpinum is one of the five most often recorded Hebeloma species in Greenland, with 36 records (almost 10%) of those considered here. This is in good accordance with Beker et al. (2016), who pointed out that this is “the most common Hebeloma species we have collected in arctic/alpine areas”. It occurs all over Greenland, from Sermiliarsuk in the south (61.6°N) to Zackenberg (74.5°N) and V. Clausen Fjord (77.5°N) in the north. In Constable Pynt in East Greenland in 2017 it was the most common of all mushrooms. In Europe, it is known from the major mountain ranges (the Alps, the Pyrenees, the Tatras, the Carpathians, Black Mountains in Montenegro), from supraboreal Iceland (Beker et al. 2016). It has been reported in North America from the Rocky Mountains (Montana, Cripps et al. 2019). Arctic-alpine, boreal and subarctic.

Habitat and ecology

The 36 collections are all from calcareous localities. The preferred host is Dryas integrifolia but possibly also D. octopetala. When these two occur together as in NE Greenland, they often hybridize, and can be difficult to identify. Only a few collections are reported with other hosts like Salix arctica, S. herbacea, Betula pubescens, B. nana and even Bistorta vivipara. The only record from Rocky Mountains was associated with S. arctica and S. glauca. Beker et al. 2016 also have records with S. polaris, S. retusa and S. reticulata.

Notes

The shape of the cheilocystidia clearly points to subsect. Crustuliniformia. Within this subsection, it is recognized among the other species by its habitat in arctic-alpine localities, the number of lamellae being usually between 40 and 60 and the size of the spores, on average > 11 μm long and > 6 μm wide. The squat and robust stature is a good character in the field.

Hebeloma bellotianum Berk. is a closely related or synonymous species from Bellot Island in the Canadian Arctic (Eberhardt et al. 2015b). Unfortunately, attempts to sequence the type have been unsuccessful. It has spores on ave. 14.7 × 7.1 µm whereas the largest average measurements of 72 collections of H. alpinum is 13.7 × 7.7 µm.

Hebeloma arcticum Beker & U. Eberh. sp. nov.

MycoBank No: 838874
Figs 22, 23

Type

Greenland. Sisimiut: at the bridge on the road to the airport (approx. 66.944317N, 53.670444W, alt. approx. 0 m a.s.l.), 14 Aug. 2016, H. Knudsen (HK16.119) (Holotype: C-F-104149; Database Record: HJB17673; Genbank: ITS = MW445587, Tef1a = MW452584 and RPB2 = MW452593).

Figure 22. 

Hebeloma arcticum A HK16.119 (holotype), photograph H. Knudsen B distribution of cited collections.

Diagnosis

Favoring arctic type habitats with many cheilocystidia clavate-stipitate and rather strongly dextrinoid but indistinctly ornamented spores.

Etymology

arcticus (adj. Latin), meaning the arctic, to emphasize the habitat within which this mushroom has been discovered.

Macroscopic description

Cap (1.7–) 2.4–2.9 (–3.8) cm, plano-convex, with or without suggestion of obtuse umbo, with decurved margin then applanate, only weakly viscid even after heavy rainfall, dull, almost glabrous, marginal zone whitish pale due to a fine adpressed tomentum, often eroded, usually bicolored, center ochre, paler towards the margin becoming very pale brownish, hardly hygrophanous but a few hygrophanous dots. Lamellae emarginate with tooth, ventricose, number of lamellae {L} 36–44, up to 4 mm wide, initially pale, darker (clay buff) at maturity with whitish fimbriate edge and usually some watery droplets or droplets visible with a x10 lens. Stem (2.8–) 4.1–4.4 (–6.0) × 0.5–0.7 (–0.9) cm, to 0.6–0.9 cm at base, whitish fibrillose to pruinose, cylindrical, narrowly fistulose, downwards pale yellowish to pale brownish when rubbed. Context firm, thick particularly in center, whitish pale, watery when moist, in age slightly brownish downwards in stipe. Smell weakly herbaceous-raphanoid. Taste mild. Spore print at most clay buff (Munsell 10YR6/4; in TB 90.071).

Figure 23. 

Hebeloma arcticum HK16.119 (holotype) A spores ×1600 and B spore ornamentation ×1600 in Melzer’s reagent C spores and D spore ornamentation ×1600 in KOH E basidia cheilocystidia and F cheilocystidia ×1000 in Melzer’s reagent G caulocystidia ×500 in KOH H cutis ×125 in KOH. Scale bars: 5 µm (A–F); 10 µm (G); 50 µm (H); microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, ellipsoid or ovoid, on ave. (across eight collections) 10.8–12.0 × 6.4–6.9 µm, ave. Q = 1.65–1.83, (for the holotype, measuring 102 spores, 5% to 95% percentile range 10.4–13.2 × 5.9–7.2 µm with median 11.9 × 6.5 µm and ave. 11.9 × 6.5 µm and S.D. for length 0.84 µm and for width 0.39 µm, and Q value 5% to 95% percentile range 1.57–2.04, with median 1.83 and ave. 1.83 with S. D. 0.14), yellow brown, guttulate, not papillate, almost smooth (O1), perispore not loosening (P0), distinctly to strongly dextrinoid (D2 D3). Basidia (20) 22–37 × 6–10 μm; ave. Q 3.0–3.7, (for the holotype 25–37 × 7–9, ave. Q 3.6), mostly four-spored. Cheilocystidia mainly clavate-stipitate, sometimes clavate-ventricose, more rarely capitate-stipitate, occasional apical or median wall thickening, sometimes septate (occasionally clamped), on ave. 36–57 × 6–9 (apex) × 4–5 (middle) × 4–6.5 (base) µm, ratios A/M = 1.5–2.3, A/B = 1.2–2.0, B/M = 1.0–1.4, (for the holotype, width near apex, 5% to 95% percentile range 6.5–8.3 µm, with median 7.4 µm and ave. 7.4 µm with S.D. 0.63 µm and over all 45 × 7.4 (apex) × 5 (middle) × 6.5 (base) µm). Pileipellis an ixocutis, up to 90 µm thick (measured from exsiccata), hyphae up to 6 µm broad, none encrusted; trama elements beneath subcutis isodiametric to ellipsoid or thick sausage-shaped, up to 17.5 µm wide. Caulocystidia similar to cheilocystidia, up to 90 µm long.

Other collections examined

S-Greenland: Paamiut, 62.01°N, 49.4°W, 31 Aug 1986, T. Borgen (TB86.277A, C-F-103571), 10 m, with S. arctophila, 62.01°N, 49.4°W, 4 Sep 1990, T. Borgen (TB90.083, C-F-103555), 10 m, with Salix glauca and Bistorta vivipara in fenland. Paamiut, 62.01°N, 49.4°W, 1 Sep 1990, T. Borgen (TB90.071, C-F-103483), 10 m, with Salix glauca and Bistorta vivipara. Paamiut, near cemetery, 61.9941°N, 49.6666°W, 21 Aug 2008, T. Borgen (TB08.153, C-F-106751), 15 m, with Salix glauca. W-Greenland: Kangerlussuaq, Ringsødalen, Ringsøen, 66.9853°N, 50.9464°W, 9 Aug 2016, T. Borgen (TB16.095, C-F-103584), 180 m, with Salix glauca. Kangerlussuaq, Ringsødalen, Ringsøen, 66.9853°N, 50.9464°W, 9 Aug 2016, H. Knudsen (HK16.044, C-F-104080), 180 m, with Salix glauca. Kangerlussuaq, Russels Glacier, 67.0977°N, 50.2318°W, 12 Aug 2000, S.A. Elborne (SAE-2000.021-GR, C-F-108472), 220 m, with Salix glauca.

Distribution

This is a new species known from a number of records in the Low Arctic zone in southern and western Greenland. The fact that it was collected several times independently may indicate that it is quite common in these areas.

Habitat and ecology

Eight collections, seven with Salix glauca one with S. arctophila. Most collections are from mineral-poor ground.

Notes

The mainly clavate-stipitate cheilocystidia indicate that this species belongs in H. sect. Denudata and there in H. subsect. Crustuliniformia.Few species of the subsection have almost smooth spores or spores that are rather strongly dextrinoid. The combination of almost smooth and rather strongly dextrinoid spores is unique in this subsection. Molecular results support its placement within this subsection. Within H. sect. Denudata, based on the spore characters, H. arcticum is readily identifiable. To be noted is also the unusual shape of the spores; while many spores are amygdaloid, many others appear more ellipsoid or cylindrical, again uncommon for this section of Hebeloma. As Figs 5A-B show, H. arcticum is well distinct from related taxa and is in a supported clade (Fig. 5B) with other members of H. subsect. Crustuliniformia, but is not a member of the H. alpinum-complex. The clade of the species is supported by 100% bootstrap in the analysis of three loci (Fig. 5B), but based on current knowledge, ITS alone is sufficient to recognize the taxon; in the ITS tree (not shown) calculated prior to concatenation of the data, H. arcticum received 84% bootstrap support.

Hebeloma aurantioumbrinum Beker, Vesterh. & U. Eberh.; Eberhardt, Beker & Vesterholt, Persoonia 35: 116, 2015.

Fig. 24

Macroscopic description

Cap 0.8–3.6 cm in diameter, umbonate or campanulate, sometimes slightly tomentose or adpressed subtomentose, at high magnification, margin smooth, tacky when moist, not generally hygrophanous, but often with hygrophanous spots, uniformly colored or variably bicolored, at center yellow brown to cinnamon to umber, but with orange elements, at margin pinkish buff to clay buff, usually very thin, without traces of any veil. Lamellae initially whitish then becoming darker and brown with maturity, emarginate, maximum depth 2 mm, number of lamellae {L} 26–42, droplets present and visible, white fimbriate edge present. Stem 1.0–4.0 × 0.15–0.5 cm, whitish lengthily fibrillose on whitish-pale ground, then sordid buff or yellowish, cylindrical, occasionally clavate, stem Q (4.7–)5.5–7, pruinose, particularly at apex. Context firm, stem interior stuffed, flesh not discoloring from base. Smell raphanoid, sometimes weakly. Taste mild or slightly bitter. Spore deposit clay buff.

Figure 24. 

Hebeloma aurantioumbrinum A SAE-2016.146, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2016.146 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, not or weakly papillate, on ave. 10.0–12.0 × 6.0–7.0 µm, ave. Q = 1.6–1.9, pale brown to yellow-brown to brown, guttulate, almost smooth to weakly ornamented (O1 O2 (O3)), perispore not or somewhat loosening (P0 P1), indistinctly to weakly dextrinoid (D1 D2). Basidia 28–38(-43) × 7–9(–11) µm, ave. Q = 3.2–4.4, mostly four-spored. Cheilocystidia clavate-stipitate, occasionally spathulate-stipitate or clavate-lageniform, occasionally characteristically with a median wall thickening, geniculate or septate, on ave. 45–61 × 7–8.5 (apex) × 4–5 (middle) × 4.5–5.5 (base) µm, with yellow contents, ratios A/M = 1.61–1.95, A/B = 1.62–1.98, B/M = 0.97–1.18. Epicutis an ixocutis, up to 70 µm thick (measured from exsiccata), maximum hyphae width 6 µm, sometimes encrusted, trama elements beneath subcutis ellipsoid up to 6 µm wide. Caulocystidia similar to cheilocystidia, up to 75 µm long.

Collections examined

S-Greenland: Kangilineq/Kvaneøen, 61.95°N, 49.47°W, 25 Aug 1990, T. Borgen (TB90.057, C-F-103482), 40 m. Kangilinnguit, bottom of Laksebund, 61.25°N, 48.08°W, 21 Aug 2018, H. Knudsen (HK18.296, C-F-111114), 100 m, in tundra. North of Tasiusaq, across the fjord from Narsarsuaq, 61.17°N, 45.61°W, 31 Jul 1993, E. Rald (ER 93.091, C-F-104321), 150 m, in Sphagnum at the lakeside. Nugarssuk, 60.26°N, 44.76°W, 9 Aug 1993, E. Rald (ER 93.262, C-F-104315), 0 m. Paamiut, 62.01°N, 49.4°W, 23 Aug 1985, T. Borgen (TB85.239, C-F-103459), 90 m, with Salix herbacea and Salix arctophila in bog. Paamiut, 62.01°N, 49.4°W, 5 Aug 1993, T. Borgen (TB93.070, C-F-103502), 10 m. Paamiut, 62.01°N, 49.4°W, 1 Sep 1990, T. Borgen (TB90.072, C-F-103484), 10 m, with Salix glauca and Bistorta vivipara. Paamiut, 62.01°N, 49.4°W, 17 Aug 1990, T. Borgen (TB90.041, C-F-103481), 10 m, with Salix glauca. Paamiut, 62.01°N, 49.4°W, 19 Aug 1985, T. Borgen (TB85.217, C-F-103526), 10 m, with Salix herbacea in snowbed. Paamiut, 62.01°N, 49.4°W, 31 Aug 1986, T. Borgen (TB86.277B, C-F-137117), 10 m, with Salix sp. Paamiut, 62.01°N, 49.4°W, 19 Aug 1984, T. Borgen (TB84.150, C-F-119792), 15 m, with Salix arctophila and Bistorta vivipara in fenland. Paamiut, 62.01°N, 49.4°W, 15 Aug 1984, T. Borgen (TB84.132, C-F-103461), 15 m, with Salix herbacea in snowbed. Paamiut, 62.01°N, 49.67°W, 12 Aug 1984, T. Borgen (TB84.112, C-F-119737), 20 m, with Salix sp. Paamiut, 62.01°N, 49.4°W, 16 Aug 1984, T. Borgen (TB84.135, C-F-103462), 10 m, with Salix arctophila, Bistorta vivipara in fenland. Paamiut, 62°N, 49.67°W, 26 Jul 1985, D. Boertmann (DB 85-17, C-F-119784), 25 m, with Salix sp. in bog. Paamiut, 62°N, 49.67°W, 26 Jul 1985, D. Boertmann (DB 85-28, C-F-119785), 25 m, with Salix sp. in bog. Paamiut, Avigaat, 62.23°N, 49.83°W, 22 Sep 1990, T. Borgen (TB90.133, C-F-103485), 60 m, with Salix herbacea and Bistorta vivipara. Paamiut, Navigation School area, 62.01°N, 49.4°W, 17 Aug 1990, T. Borgen (TB90.039, C-F-103546), 10 m, with Salix herbacea and Bistorta vivipara. Paamiut, Navigation School area, 62.01°N, 49.4°W, 13 Aug 1990, T. Borgen (TB90.029, C-F-103545), 10 m, with Salix herbacea. Paamiut, Navigation School area, 62.01°N, 49.4°W, 12 Aug 1990, T. Borgen (TB90.012, C-F-103547), 10 m, with Salix herbacea. Paamiut, Navigation School area, 62.01°N, 49.4°W, 12 Aug 1990, T. Borgen (TB90.011, C-F-103548), 10 m, with Salix herbacea. Paamiut, Telesletten, 62.01°N, 49.4°W, 23 Aug 1986, T. Borgen (TB86.251, C-F-103570), 10 m. W-Greenland: Kangerlussuaq, Lake Ferguson, Tasersuatsiaq, 66.96°N, 50.70°W, 22 Aug 2016, S.A. Elborne (SAE-2016.146-GR, C-F-106745), 350 m, with Salix glauca in streambed. Kangerlussuaq, NE facing slopes along Lake Ferguson, 66.99°N, 50.61°W, 12 Aug 2016, H. Knudsen (HK16.089, C-F-104118), 300 m. Nuuk, 64.19°N, 51.67°W, 14 Aug 1987, S.A. Elborne (SAE-1987.113-GR, C-F-119789), 300 m, with Salix herbacea in snowbed. Nuuk, airport area, 64.19°N, 51.67°W, 5 Aug 1987, H. Knudsen (HK87.004, C-F-119790), 100 m. Nuuk, Lille Malene, 64.19°N, 51.67°W, 17 Aug 1987, H. Knudsen (HK87.218, C-F-119788), 100 m. N-Greenland: Qaanaaq, 77.47°N, 69.18°W, 8 Aug 1988, S.A. Elborne (SAE-1988.149-GR, C-F-1461), 50 m. Danmarkshavn, Mørkefjord Station, 76.93°N, 20.32°W, 7 Aug 1984, B. Lauritsen (BL s.n., C-F-3637), 10 m. Danmarkshavn, Mørkefjord Station, 76.93°N, 20.32°W, 26 Jul 1982, B. Lauritsen (BL s. n., C-F-119797), 10 m. Zackenberg, Gadekæret, 74.5°N, 21°W, 21 Jul 1999, T. Borgen (TB99.044, C-F-119751), 40 m, with Salix arctica and Bistorta vivipara in scrubland. Zackenberg, Teltdammen, 74.5°N, 21°W, 5 Aug 2006, T. Borgen (TB06.091, C-F-119741), 30 m, with Salix arctica in scrubland. Zackenberg, Teltdammen, 74.5°N, 21°W, 5 Aug 2006, T. Borgen (TB06.091, C-F-119781), 30 m, with Salix arctica in scrubland. Zackenberg, Ulvehøj, 74.47°N, 21°W, 11 Aug 2006, T. Borgen (TB06.150, C-F-119768), 40 m, with Salix arctica in snowbed. Zackenberg, Østkæret, 74.47°N, 21°W, 22 Aug 2006, T. Borgen (TB06.259, C-F-119771), 40 m, with Salix arctica in fenland. E-Greenland: Jameson Land, Constable Pynt, beginning of Lollandselv, 70.92°N, 23.18°W, 31 Jul 1989, S.A. Elborne (SAE-89.430, C-F-2424), 500 m, with Salix arctica on riverside. Jameson Land, Constable Pynt, camp at ‘Vindelv’, river wnw of pt.330, 71°N, 23.47°W, 30 Jul 1989, H. Knudsen (HK89.366, C-F-2309), 230 m, with Salix arctica. Jameson Land, Constable Pynt, delta of Jyllandselv, 70.68°N, 24.06°W, 28 Jul 1988, D. Boertmann (DB GR 88-22, C-F-119787), 0 m. Jameson Land, Constable Pynt, Gåseelv, 70.77°N, 22.7°W, 18 Jul 1989, S.A. Elborne (SAE-89.121, C-F-2327), 80 m, with Salix arctica on lakeside. Lower east Skeldal, Kong Oscars Fjord, 72.27°N, 24.28°W, 17 Aug 1962, T.T. Elkington (s.n., C-F-6992), 150 m, with Cassiope in tundra and heathland. Lower east Skeldal, Kong Oscars Fjord, 72.27°N, 24.28°W, 17 Aug 1962, T.T. Elkington (s.n., C-F-6993), 150 m, with Cassiope, tundra and heathland.

Distribution

Hebeloma aurantioumbrinum is one of the five most commonly recorded Hebeloma in Greenland with 10.5% of the records considered here. It is common and widely distributed in arctic areas in Europe (Beker et al. 2016). From alpine areas, it is known from North America (Cripps et al. 2019), but not from the well-investigated alpine mountains in Europe (Beker et al. 2016). Circumpolar, arctic-alpine.

Habitat and ecology

Forty collections with a number of hosts recorded, including: Salix herbacea (11), S. arctica (5), S. glauca (5), S. arctophila (3), Salix sp. (5), Bistorta vivipara (8, but never as the only possible associate). The localities are also scattered between wet and dry places, but favoring wet areas with S. herbacea, without having a preference for specific soil conditions. Beker et al. (2016) also found a preference for Salix, including S. polaris.

Hebeloma geminatum Beker, Vesterh. & U. Eberh.; Eberhardt, Beker & Vesterholt, Persoonia 35: 122, 2015.

Fig. 25

Macroscopic description

Cap 2.0–12.0 cm in diameter, usually convex, sometimes broadly umbonate or applanate, margin usually smooth, occasionally involute, crenulate or upturned with age, tacky when moist, not hygrophanous usually uniformly colored, rarely bicolored, at center usually cream or whitish, sometimes a little yellowish, at margin paler, cream to whitish, without any traces of veil. Lamellae initially very pale brown, later clay-brown, adnate to emarginate, maximum depth 4–8 mm, number of lamellae {L} 62–100, with visible droplets and white fimbriate edge. Stem 1.5–11.0 × 0.7–1.5 {median} × 0.7–1.6 {base} cm, initially whitish, later pale brownish, initially pruinose, apex with watery droplets, cylindrical to clavate, stem Q (2.1–)2.5–9.2(–10.6), floccose. Context firm, stem interior stuffed, becoming hollow with age, flesh usually not discoloring from base. Smell raphanoid. Taste mild, raphanoid. Spore deposit brownish olive to grayish brown.

Figure 25. 

Hebeloma geminatum A HK18.379B, photograph H. Knudsen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK18.379B in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, on ave. 10.0–11.0 × 5.5–6.5 µm, ave. Q = 1.7–1.9, grayish yellow to yellow-brown to brown, guttulate, weakly to distinctly ornamented (O2 O3), perispore somewhat loosening ((P0) P1 (P2)), indextrinoid or indistinctly dextrinoid (D0 D1). Basidia 25–35 × 7–9 µm, ave. Q = 3.3–4.3, mostly four-spored. Cheilocystidia clavate-stipitate or spathulate-stipitate and occasionally capitate-stipitate or clavate-lageniform, occasionally characteristically bifurcate, with a median wall thickening, septate or sinuate, on ave. 50–72 × 8–10.5 (apex) × 4–4.5 (middle) × 3.5–5 (base) µm, ratios A/M = 1.76–2.57, A/B = 1.68–2.85, B/M = 0.81–1.19. Epicutis an ixocutis, 110–200 µm thick (measured from exsiccata), maximum hyphae width 5–8 µm, variably encrusted, trama elements beneath subcutis cylindrical, ellipsoid, sausage-shaped up to 16 µm wide. Caulocystidia similar to cheilocystidia, up to 70 µm long and 12 µm wide.

Collections examined

S-Greenland: Sermiliarsuk, Sioralik, Aasivii, 65.53°N, 48.33°W, 30 Aug 1997, T. Borgen (TB97.154a, C-F-103508), with Betula pubescens, 50 m. W-Greenland: Kangerlussuaq, c. 2 km W of the Airport, Mt. Hassel, 67.06°N, 50.68°W, 10 Aug 2000, A-M. Larsen, T. Borgen (TB00.065, C-F-103514), 50 m, with Salix glauca in copse. Kangerlussuaq, Hassells Fjeld, Kløftsøerne, 67.01°N, 50.71°W, 27 Aug 2018, H. Knudsen (HK18.379B, C-F-111117), 300 m, with Salix glauca, Betula nana in heathland.

Distribution

Only known from two localities in southwestern Greenland. Generally distributed over much of Europe, but lacking in the Mediterranean region. Northernmost European localities are from Norway at just above 70°N. This species has already been recorded in North America (https://mycoportal.org/portal/collections/list.php, accessed 2 Dec 2020) but how common it is, is not yet known. Temperate and boreal, with a few records from the Low Arctic zone.

Habitat and ecology

Only three collections with Salix glauca, Betula nana and B. pubescens, but when recorded on 27 Aug. 2018, on the south-exposed side of Mt. Hassell, it was numerous and, remarkably, the only agaric present. From Europe, there are a number of hosts recorded, including many deciduous and coniferous trees (Beker et al. 2016).

Hebeloma helodes J. Favre; Beitr. Kryptfl. Schweiz 10(3): 214, 1948.

Fig. 26

Macroscopic description

Cap 1.3–3.8 cm in diameter, convex or sometimes weakly umbonate becoming umbilicate with age, margin usually involute at least when young, tacky when moist, not hygrophanous, mostly uniformly colored or variably bicolored, at center light ochraceous to yellowish to yellowish-brown or pale reddish brown and at margin whitish to pale cream, sometimes with remains of universal veil. Lamellae initially whitish later persistently cream, attachment emarginate, occasionally adnate, maximum depth 3–4.5 mm, number of lamellae {L} 33–54, droplets present and visible at least with × 10 lens, white fimbriate edge present. Stem 1.5–6.5 × 2.0–7.0 {median} × (2–)2.9–6.5(–7) {base} cm, whitish tomentose flocculose in the entire length, cylindrical to clavate, stem Q (3.3–)4.7–20, floccose. Context firm, stem interior stuffed, later becoming hollow, stem flesh not discoloring from base but with some weak discoloration with age. Smell raphanoid. Taste mild, raphanoid. Spore deposit dark olive buff to brownish olive.

Figure 26. 

Hebeloma helodes A TB88.114, photograph T. Borgen B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of TB88.114 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, on ave. 9.0–11.0 × 5.0–6.0 µm, ave. Q = 1.6–2.0, yellow to pale brown, usually guttulate, weakly to distinctly ornamented (O2 O3), perispore somewhat to distinctly loosening ((P0) P1 P2), indextrinoid to indistinctly dextrinoid, rarely distinctly dextrinoid (D0 D1 (D2)). Basidia 22–27(–30) × 7–9 µm, ave. Q = 2.8–4.2, mostly four-spored. Cheilocystidia clavate-stipitate to capitate stipitate, occasionally more clavate-lageniform, often with characteristic apical or less frequently median wall thickening, occasionally septate, on ave. 44–63 × 8.5–11.5 (apex) × 4–5 (middle) × 3.5–5.5 (base) µm, ratios A/M = 1.90–2.86, A/B = 2.02–3.38, B/M = 0.77–1.17. Epicutis an ixocutis, 100–135 µm thick (measured from exsiccata), maximum hyphae width 5–6 µm, sometimes encrusted, trama elements beneath subcutis sausage-shaped up to 15 µm wide. Caulocystidia similar to cheilocystidia, but short, up to 11 µm wide at apex.

Collections examined

S-Greenland: Kangilinnguit, 61.14°N, 48.6°W, 10 Aug 1985, T. Borgen (TB85.072, C-F-103460), 25 m, with Alnus alnobetulae in copse. Kangilinnguit, 61.14°N, 48.6°W, 11 Aug 1985, T. Borgen (TB85.090, C-F-103476), 25 m, with Alnus alnobetulae in copse. Kangilinnguit, 61.23°N, 48.10°W, 10 Aug 1985, T. Borgen (TB85.065, C-F-103525), 25 m, with Salix glauca in heathland. Narsaq, 60.91°N, 46.05°W, 3 Aug 1993, E. Rald (ER 93.153, C-F-104317), 20 m, with Salix glauca in scrubland. Paamiut, 62.01°N, 49.4°W, 29 Aug 1988, T. Borgen (TB88.114, C-F-4003), 50 m, in scrubland.

Distribution

Only found in a few localities in southern Greenland. Generally distributed in warm and cold temperate Europe with a few records from subarctic Norway and Finland and missing in southern Europe. The Greenland records fit well with the European records, the records from southern Greenland (Paamiut, 62.01) being the northernmost hitherto found.

Habitat and ecology

Five collections from heath- and scrubland recorded with Salix glauca and Alnus alnobetulae. Beker et al. (2016) suspect association with various deciduous tree families.

Hebeloma louiseae Beker, Vesterh. & U. Eberh.; Eberhardt, Beker & Vesterholt, Persoonia 35: 127, 2015.

Fig. 27

Macroscopic description

Cap 0.7–2.2 cm in diameter, convex to broadly umbonate, margin smooth to crenulate, tacky when moist, not hygrophanous, uniformly colored or indistinctly bicolored, at center clay-buff to dark olive buff, margin very thin, grayish pink or central color extending to margin, with no traces of veil. Lamellae initially pale, later sordid clay-brown, emarginate, maximum depth 2 mm, number of lamellae {L} 28–40, droplets often absent but occasionally visible even with the naked eye, white fimbriate edge present. Stem 0.8–2.5 × 0.2–0.3 {median} × 0.1–0.3 {base} cm, initially pale, later sordid brownish, cylindrical to clavate, occasionally tapering, stem Q (4–)4.6–7.6(–9.2), pruinose to slightly fibrillose. Context firm, interior stuffed, flesh discoloring weakly from base. Smell absent or raphanoid. Taste not recorded. Spore deposit grayish brown.

Figure 27. 

Hebeloma louiseae A SAE-2017.125, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of HK17.128A.146 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, limoniform, weakly to strongly papillate, on ave. 12.0–13.0 × 7.0–7.5 µm, ave. Q = 1.6–1.8, yellow brown to brown, guttulate, almost smooth to weakly ornamented (O1 O2), perispore not loosening (P0), indextrinoid to indistinctly dextrinoid (D0 D1 (D2)). Basidia 24–56 × 6–12 µm, ave. Q = 3.2–4.6, mostly four-spored. Cheilocystidia clavate-stipitate, occasionally spathulate-stipitate or capitate-stipitate or clavate-lageniform, occasionally with characteristic apical wall thickening, occasionally bifurcate, septate or sinuate, on ave. 42–59 × 6–11 (apex) × 4.0–5.5 (middle) × 3.5–6.0 (base) µm, ratios A/M = 1.48–2.51, A/B = 1.99–2.92, B/M = 0.81–1.24. Epicutis an ixocutis, up to 100 µm thick (measured from exsiccata), maximum hyphae width 6 µm, sometimes encrusted, trama elements beneath subcutis cylindrical, sausage-shaped. Caulocystidia similar to cheilocystidia, up to 75 µm long.

Collections examined

W-Greenland: Kangerlussuaq, c. 2 km W of the Airport, 67.06°N, 50.68°W, 10 Aug 2000, A-M. Larsen, T. Borgen (TB00.061, C-F-103518), 50 m, with Salix glauca in ditch. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.42°W, 25 Aug 2016, S.A. Elborne (SAE-2016.197-GR, C-F-106747), 110 m, with Salix glauca in dune slack. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 6 Aug 2017, H. Knudsen (HK17.128, C-F-105029), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 6 Aug 2017, S.A. Elborne (SAE-2017.125A-GR, C-F-106763), 40 m, with Salix arctica at riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.77°N, 22.69°W, 6 Aug 2017, S.A. Elborne (SAE-2017.125B-GR, C-F-106763), 15 m, with Salix arctica at riverside.

Distribution

Recently described from Svalbard (Beker et al. 2016). The five Greenland collections all occurred north of 67°N and thus provide evidence that H. louiseae is a species of the High Arctic zone. It has not yet been recorded in alpine regions. The Greenland collections are the first from North America and the first outside Europe.

Habitat and ecology

Five collections, with Salix glauca and S. arctica in calcareous soil and seemingly moist localities. From Svalbard it was recorded with S. polaris (Beker et al. 2016).

Notes

Hebeloma louiseae is easily recognized among the arctic Hebeloma species by the small basidiomes, the relatively few lamellae and the large basidia, although not present in every collection.

Hebeloma minus Bruchet; Bull. mens. Soc. linn. Lyon 39(6(Suppl.)): 126, 1970.

Fig. 28

Macroscopic description

Cap 0.9–3.1 cm in diameter, convex to umbonate, margin smooth, sometimes involute, tacky when moist, sometimes hygrophanous especially when frosted, almost uniformly colored, occasionally more bicolored, at center dark pinkish buff to dark olive buff or clay-buff to brownish olive, grayish brown or umber, at margin pinkish to grayish buff or clay-buff, occasionally pruinose (givré), without any traces of veil. Lamellae clay buff, emarginate to adnate, maximum depth 3.5–5 mm, number of lamellae {L} 30–34, droplets often visible, occasionally absent or visible with × 10 lens, white fimbriate edge present. Stem 1.0–4.0 × 0.1–0.8 {median} × 0.1–1.0 {base} cm, stem Q (4–)4.8–14(–20), fairly strongly whitish fibrillose-flocculose, cylindrical to clavate, rarely bulbous, fibrillose, pruinose, floccose, particularly noticeable at apex. Context firm, stem interior stuffed, hollow with age, flesh discoloring from base at most very weakly. Smell raphanoid. Taste mild, occasionally weakly bitter or raphanoid. Spore deposit brownish olive.

Figure 28. 

Hebeloma minus A HJB11945 (from Svalbard), photo H.K.J. Beker, reproduced by kind permission from Beker et al. (2016) B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of TB86.085 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, occasionally limoniform, papillate, on ave. 11.0–13.0 × 6–7.5 µm, ave. Q = 1.6–1.9, yellow to brown, usually guttulate, weakly to distinctly ornamented (O2 O3), perispore not or somewhat loosening (P0 P1 (P2)), indistinctly to weakly dextrinoid (D1 D2). Basidia 27–40 × 7–11 µm, ave. Q = 2.8–4.1, mostly four-spored. Cheilocystidia capitate-stipitate, clavate-stipitate or occasionally clavate-lageniform, occasionally with characteristic apical or median wall thickening, sometimes geniculate or septate, on ave. 40–60 × 8–11.0 (apex) × 3.5–5 (middle) × 3–6 (base) µm, ratios A/M = 1.87–2.67, A/B = 1.81–3.02, B/M = 0.84–1.24. Epicutis an ixocutis, 40–100 µm thick (measured from exsiccata), maximum hyphae width 6–6.5 µm, some encrusted, trama elements beneath subcutis cylindrical, sausage-shaped, up to 30 µm wide. Caulocystidia similar to cheilocystidia but larger, up to 100 µm long.

Collections examined

S-Greenland: Qassiarsuk, Tasiusaq, 61.15°N, 45.52°W, 21 Jul 1984, T. Læssøe (TL 84.041, C-F-119793), 25 m. W-Greenland: Qeqertarsuaq/Disko, Godhavn, Østerlien, 69.25°N, 53.54°W, 30 Jul 1986, T. Borgen (TB86.085, C-F-104302), 40 m, with Salix glauca in copse.

Distribution

Only two collections, from southwestern Greenland. Although described 50 years ago, H. minus is still only known from a few collections in Iceland and Svalbard, and from the French, Italian and Swiss Alps at 2200–2700 m. The Icelandic localities are from the upper boreal zone, but close to the oroboreal zone, which is equivalent to the alpine zone (Rivas-Martinez et al. 2004). The Svalbard localities are in the High Arctic, whereas the two Greenland collections are both from the Low Arctic zone. This is a truly arctic-alpine species. It is new to North America and these are the first records outside Europe.

Habitat and ecology

Two collections, one recorded with Salix glauca. Beker et al. (2016) list S. herbacea, S. reticulata, S. retusa and Dryas octopetala as hosts from arctic and alpine sites in Europe.

Hebeloma subsect. Clepsydroida Beker & U. Eberh.; Fungal Biol. 120: 82, 2015 (“2016”)

Cheilocystidia distinctly broadened at apex, base ± swollen, wall often thickened at the middle. Lamellae edge often with exuded drops, but sometimes dried away.

Hebeloma ingratum Bruchet; Bull. mens. Soc. linn. Lyon 39: 125, 1970.

Fig. 29

Macroscopic description

Cap 1.8–7.5 cm in diameter, convex to umbonate, margin often involute when young, sometimes serrate or crenulate, tacky when moist, occasionally hygrophanous, usually bicolored but sometimes unicolored, at center usually brown tones from ochraceous to cinnamon, at margin cream, occasionally 3–4 mm from margin a circle of water spots can be visible, without any traces of veil. Lamellae pale clay brown, adnate to emarginate, maximum depth 3–5 mm, number of lamellae {L} 50–80, droplets absent or visible with × 10 lens, occasionally with naked eye, white fimbriate edge usually present, sometimes very strongly. Stem 1.5–6.8 × 0.4–1.2 {median} × 0.5–1.3 {base} cm, stem Q (2.5–)4.4–11.1(–11.5), white lengthily fibrillose and white flocculose, most distinct in the upper half, cylindrical to clavate, occasionally subbulbous to bulbous. Context firm, interior stuffed, later hollow, rarely with superior wick, flesh not discoloring from base or sometimes weakly. Smell raphanoid. Taste raphanoid, usually mild, but sometimes bitter. Spore deposit dark olive buff to brownish olive to yellowish brown or umber.

Figure 29. 

Hebeloma ingratum A SAE-2016.208, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2016.208 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, sometimes limoniform, variably papillate from absent to very strongly, on ave. 10.0–11.0 × 5.5–6.5 µm, ave. Q = 1.7–1.9, yellow to yellow brown, usually guttulate, weakly to distinctly ornamented (O2 O3), perispore somewhat to distinctly loosening ((P0) P1 P2), indistinctly to weakly dextrinoid (D1 D2). Basidia (20–)24–30(–33) × 6–10 µm, ave. Q = 3.2–3.9, mostly four-spored. Cheilocystidia clavate-lageniform, occasionally clavate-stipitate or ventricose, occasionally with characteristic apical or median wall thickening, sometimes geniculate or septate, on ave. 42–55 × 5–7 (apex) × 3.5–4.5 (middle) × 5–6.5 (base) µm, ratios A/M = 1.4–1.74, A/B = 0.9–1.28, B/M = 1.4–1.64. Epicutis and ixocutis, 75–300 µm thick (measured from exsiccata), maximum hyphae width 5–6.5 µm, sometimes encrusted, trama elements beneath subcutis oblong to sausage-shaped up to 15 µm wide. Caulocystidia up to 150 µm long, often cylindrical or slenderly clavate at the apex.

Collections examined

S-Greenland: Paamiut, Taartoq/Mørke Fiord, 62.01°N, 49.26°W, 4 Sep 1993, T. Borgen (TB93.205, C-F-103501), 20 m, with Betula glandulosa and Salix glauca in heathland. W-Greenland: Kangerlussuaq, fjord shore south of town, 66.98°N, 50.69°W, 26 Aug 2016, S.A. Elborne (SAE-2016.208-GR, C-F-106748), 20 m, with Salix glauca and Betula nana along streamside. Kangerlussuaq, Sandflugtsdalen, 67.02°N, 50.42°W, 21 Aug 1987, H. Knudsen (HK87.262, C-F-119732), 200 m, with Betula nana and Salix glauca. Sisimiut, 4 km E of the village, 66.94°N, 53.59°W, 18 Aug 2000, E. Ohenoja (EO18.8.00.36, OULU F050503), 70 m, in heathland.

Distribution

Only known from two well-studied areas in low arctic southern and western Greenland, north to 67°. The general European distribution is in the Temperate zone, missing in southern Europe and with one record in the Hemiboreal zone in Finland. The Greenland records are the northernmost known and the first from North America and the first outside Europe.

Habitat and ecology

Four collections from heath- and scrubland. Hosts are uncertain, both Betula nana and B. glandulosa as well as Salix glauca were present. No preference for a specific ecology. Beker et al. (2016) also list Betula and Salix, but also Fagus, Quercus and Populus as possible hosts.

Hebeloma vaccinum Romagn.; Bull. trimest. Soc. mycol. Fr. 81: 333, 1965.

Fig. 30

Macroscopic description

Cap 0.9–6.1 cm in diameter, convex, later umbonate, margin usually involute when young, sometimes crenulate or scalloped, tacky when moist, not hygrophanous, usually bicolored, but sometimes almost unicolored, at center from clay-buff to yellowish brown and dark olive buff to dark brick or rust brown, at margin cream to gray-buff to clay-buff, pale and very thin, without any traces of veil. Lamellae light, then sordid gray-brown, adnexed to emarginate, maximum depth 2–6 mm, number of lamellae {L} 32–60, droplets visible with naked eye or sometimes with × 10 lens, white fimbriate edge present. Stem 0.9–5.5 × 0.3–1.3 {median} × 0.3–1.3 {base} cm, stem Q (2.2–)2.7–9(–13.3), white flocculose on pale brown ground, downwards watery gray-brown, later watery ochre-brown, not darker at base, base cylindrical to clavate or bulbous, sometimes with encrusted sand, pruinose to floccose, particularly at apex. Context firm, stem interior stuffed, later hollow, sometimes with superior wick, flesh not discoloring from base. Smell raphanoid, sometimes of cocoa. Taste sometimes raphanoid, sometimes bitter. Spore color brownish olive to sepia.

Figure 30. 

Hebeloma vaccinum A SAE-2017.194, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2017.194 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores mainly amygdaloid, sometimes fusoid or limoniform, papillate, on ave. 12.0–14.5 × 6.5–8.0 µm, ave. Q = 1.6–2.0, yellow-brown to brown, sometimes guttulate, distinctly to fairly strongly ornamented ((O2) O3 O4), perispore somewhat to distinctly loosening ((P0) P1 P2), weakly to rather strongly dextrinoid (D2 D3). Basidia 27–39 (–42) × 7–12 µm, ave. Q = 3–4.5, mostly four-spored. Cheilocystidia clavate-lageniform, capitate-lageniform, sometimes clavate-stipitate or capitate-stipitate or ventricose, occasionally characteristically with apical or median wall thickening, sometimes geniculate, septate or sinuate, on ave. 41–64 × 6–8 (apex) × 3–5 (middle) × 4.5–8 (base) µm, ratios A/M = 1.43–2.31, A/B = 0.84–1.53, B/M = 1.28–1.92. Epicutis and ixocutis, 40–125 µm thick (measured from exsiccata), maximum hyphae width 5–6.5 µm, sometimes encrusted, trama elements beneath subcutis sausage-shaped, occasionally spherical up to 16 µm wide. Caulocystidia similar to cheilocystidia, up to 90 µm long, often with many septa.

Collections examined

S-Greenland: Narsarsuaq, 61.08°N, 45.26°W, 7 Aug 1985, T. Borgen (TB85.045, C-F-103477), 150 m, with Dryas integrifolia in heathland. Narsarsuaq, Hospitalsdalen, 61.17°N, 45.41°W, 1 Aug 1992, E. Rald (ER 92.038, C-F-104308), 60 m, with Salix glauca and Betula glandulosa. Narsarsuaq, 61.17°N, 45.41°W, 17 Aug 2015, H. Knudsen (HK15.069, C-F-8222), 60 m, with Salix glauca and Betula pubescens at pathside. Qassiarsuk, Tasiusaq, 61.15°N, 45.52°W, 19 Aug 1992, E. Rald (ER 92.323, C-F-104311), 25 m. Tasiusaq, 61.14°N, 45.63°W, 28 Jul 1993, E. Rald (ER 93.022, C-F-104320), 20 m, with Salix glauca in fenland. N-Greenland: Zackenberg, Aucellabjerg, 74.5°N, 21°W, 20. Aug. 2006, T. Borgen (TB06.246, C-F-119780), 300 m, with Salix arctica and Bistorta vivipara in scrubland. Zackenberg, just E of the station, 74.5°N, 21°W, 26 Jul 1999, T. Borgen (TB99.109, C-F-119755), 40 m, with Dryas sp. and Salix sp. in scrubland. Zackenberg, just S of the Field Station, 74.48°N, 20.76°W, 19 Jul 1999, T. Borgen (TB99.008, C-F-119804), 30 m, with Dryas sp. and Bistorta vivipara. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 8 Aug 2017, T. Borgen (TB17C.073, C-F-106778), 40 m, in heathland. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.71°N, 22.69°W, 10 Aug 2017, S.A. Elborne (SAE-2017.194-GR, C-F-106767), 100 m, with Salix arctica in tundra. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.022B, C-F-104911), 180 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.021, C-F-104909), 180 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.022A, C-F-104910), 180 m.

Distribution

Widely distributed in Greenland and apparently common in the localities where it was found; missing in western Greenland. It is widely distributed in the Temperate zone in Europe (Beker et al. 2016) with a few records in subarctic areas in Sweden (Härjedalen) and the Oroboreal zone in Iceland (Egilsstadir, 65°N). The Greenland collections from Zackenberg (74.5°N) are the northernmost recorded, to date. Hebeloma vaccinum was recently recorded from the alpine Rocky Mountains (Cripps et al. 2019), but these Greenland records are the first from arctic North America.

Habitat and ecology

Thirteen collections, all from calcareous or mineral rich areas. Hosts are Dryas, Salix glauca and S. arctica. Beker et al. (2016) concluded that the Salicaceae (Salix and Populus) are the host family for this species, with S. repens L. as the most often recorded host in Europe, but also S. lanata L.

Hebeloma subsect. Hiemalia Quadr.; Doc. mycol. 14: 30, 1985 (“1984”)

Cheilocystidia distinctly broadened at apex, base ± swollen, wall often thickened at the middle. Spores with a majority that are weakly ornamented (O2) and the perispore which is not consistently or distinctly loosening (rarely P2 and never P3) and the pileus color which always has brown or buff tones at least in the center.

Hebeloma hiemale Bres.; Fung. trident. 2(11–13): 52, 1892.

Fig. 31

Macroscopic description

Cap 1.1–8.0 cm in diameter, convex to umbonate, often broadly, margin smooth, sometimes involute, undulate in older specimens, tacky when moist, occasionally spotted, rarely hygrophanous, almost uniformly colored or variably bicolored, at center warm buff to grayish buff or dark pinkish buff through honey or ochraceous and dark olive buff to umber and clay pink or orange brown, at margin pale cream to cream to honey or pale pinkish buff, without any traces of veil. Lamellae when young very pale but becoming darker with maturity, emarginate to adnate, maximum depth 3–7 mm, number of lamellae {L} 35–71, droplets usually visible with naked eye or × 10 lens, occasionally absent, white fimbriate edge present. Stem (1.3–)1.5–10.75(–12) × (0.3–)0.35–1.2 {median} × (0.3–)0.55–1.4(–1.5) {base} cm, stem Q 2.5–17.2(–17.4), whitish to pale brownish at middle, hardly discoloring, gradually sordid brown in the mid portion, cylindrical to clavate, rarely subbulbous, usually pruinose particularly at apex, rarely with mycelial chords. Context firm, stem interior stuffed, becoming hollow with age and often with a superior wick, flesh often discoloring from base, particularly after handling. Smell raphanoid, sometimes with hints of cocoa, rarely absent. Taste mild to weakly bitter. Spore color dark olive buff or grayish brown through brownish olive to umber.

Figure 31. 

Hebeloma hiemale A SAE-2018.225, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2018.225 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, limoniform, variably papillate, on ave. 10.0–12.5 × 5.0–7.5 µm, ave. Q = 1.6–2.1, yellow to yellow brown, usually guttulate, weakly, occasionally distinctly ornamented ((O1) O2 (O3)), perispore not or somewhat loosening (P0 P1 (P2)), indistinctly to weakly dextrinoid ((D0) D1 D2). Basidia 23–39(-43) × 7–10 µm, ave. Q = 3.2–4.3, mostly four-spored, often stipitate. Cheilocystidia usually clavate-lageniform, but occasionally slenderly clavate, clavate-stipitate, cylindrical or ventricose, rarely spathulate-lageniform or tapering, occasionally characteristically with apical or median wall thickening, sometimes geniculate or septate, rarely sinuate or rostrate, on ave. 40–65 × 5.5–9 (apex) × 3.5–5 (middle) × 4.5–7.5 (base) µm, ratios A/M = 1.46–2.48, A/B = 0.97–1.8, B/M = 1.26–1.77. Epicutis an ixocutis, 60–200 µm thick (measured from exsiccata), maximum hyphae width 4–6 µm, sometimes encrusted, trama elements beneath subcutis cylindrical, ellipsoidal, sausage-shaped up to 17 µm wide. Caulocystidia similar to cheilocystidia, up to 75 µm long, often septate, septa sometimes clamped, many cylindrical.

Collections examined

S-Greenland, Kangilinnguit, 61.21°N, 48.12°W, 20 Aug 2018, H. Knudsen (HK18.269, C-F-111112), 125 m, in tundra. Kangilinnguit, Arsuk Fjord, 61.23°N, 48.07°W, 19 Aug 2018, S.A. Elborne (SAE-2018.225-GR, C-F-112771), 100 m, with Salix glauca and Bistorta vivipara in heathland. Kangilinnguit, at Grønnedal Hut, 61.23°N, 48.08°W, 15 Aug 1985, T. Borgen (TB85.182, C-F-103466), 400 m, with Salix herbacea and Harrimanella hypnoides in snowbed. Nanortalik, 60.08°N, 45.14°W, 12 Aug 1991, T. Borgen (TB91.136, C-F-103465), 50 m, with Salix sp. Nanortalik municipality, Qinngua valley, 60.14°N, 45°W, 9 Aug 1991, T. Borgen (TB91.112, C-F-119782), 230 m, with Salix glauca in scrubland. Narsaq, 60.91°N, 46.05°W, 13 Aug 1993, E. Rald (ER 93.330, C-F-104550), 20 m, with Salix glauca and Betula glandulosa in heathland. Narsaq, 60.91°N, 46.05°W, 3 Aug 1993, E. Rald (ER 93.152, C-F-104318), 20 m. Narsarsuaq, Hospitalsdalen, 61.1715°N, 45.41°W, 10 Aug 1984, T. Læssøe (TL 84.608, C-F-119794), 60 m. Paamiut, 62.01°N, 49.4°W, 8 Aug 1981, T. Borgen (TB81.112, C-F-103552), 10 m, with Salix glauca. Paamiut, 62.01°N, 49.4°W, 27 Aug 1993, T. Borgen (TB93.159, C-F-103496), 20 m, with Salix herbacea. Paamiut, 62.01°N, 49.4°W, 31 Aug 1995, T. Borgen (TB95.114, C-F-103504), 30 m, with Salix glauca, Betula glandulosa in heathland. Paamiut, 62.01°N, 49.4°W, 6 Sep 1990, T. Borgen (TB90.087, C-F-103540), 10 m, with Salix glauca. Paamiut, 62.01°N, 49.4°W, 6 Sep 1990, T. Borgen (TB90.084a, C-F-103549), 10 m, with Salix glauca. Paamiut, 62.01°N, 49.4°W, 8 Sep 1990, T. Borgen (TB90.104a, C-F-103550), 10 m, with Salix glauca and Salix herbacea. Paamiut, 61.99°N, 49.66°W, 22 Aug 2008, T. Borgen (TB08.157, C-F-106752), 15 m, with Salix glauca and Bistorta vivipara. Paamiut, 62.01°N, 49.4°W, 31 Aug 1993, T. Borgen (TB93.183, C-F-103497), 50 m, with Salix glauca in heathland. Paamiut, 62.01°N, 49.4°W, 8 Sep 1993, T. Borgen (TB93.210, C-F-103499), 10 m. Paamiut, 62.01°N, 49.4°W, 1 Sep 1993, T. Borgen (TB93.187, C-F-103498), 10 m, with Salix herbacea. Paamiut, 62.01°N, 49.4°W, 28 Aug 1993, T. Borgen (TB93.155, C-F-103500), 10 m, with Salix herbacea in snowbed. Paamiut, Kangilineq /Kvaneøen, 61.95°N, 49.47°W, 25 Aug 1985, T. Borgen (TB85.250, C-F-119786), 20 m, with Salix arctophila in fenland. Paamiut, Navigation School area, 62.01°N, 49.4°W, 13 Aug 1990, T. Borgen (TB90.032, C-F-103543), 10 m, with Salix herbacea in snowbed. Paamiut, Navigation School area, 62.01°N, 49.4°W, 13 Aug 1990, T. Borgen (TB90.019, C-F-103544), 10 m, with Salix herbacea and Bistorta vivipara. Paamiut, Taartoq/Mørke Fiord, 61.99°N, 49.66°W, 29 Aug 1998, T. Borgen (TB98.201, C-F-104292), 25 m, with Salix glauca. Qaqortoq, 60.72°N, 46.04°W, 13 Aug 1993, E. Rald (ER 93.302, C-F-104551), 30 m, with Salix glauca. W-Greenland: Kangerlussuaq, 67.01°N, 50.72°W, 11 Aug 1986, T. Borgen (TB86.203, C-F-103568), 50 m. Kangerlussuaq, near a glacier, 67.03°N, 50.64°W, 12 Aug 2000, E. Ohenoja (EO12.8.00.1, OULU F050224), 229 m. Kangerlussuaq, c. 2 km W of the Airport, Mt. Hassel, 67.012°N, 50.856°W, 10 Aug 2000, A-M. Larsen, T. Borgen (TB00.069, C-F-103515), 50 m, with Salix glauca in copse. Kangerluarsunnguaq, Kobbefjord, end of fiord, 64.14°N, 51.35°W, 26 Aug 2018, S.A. Elborne (SAE-2018.357-GR, C-F-112904), 100 m, with Salix glauca in copse. NW below Nasaasaaq, E-valley, E of Sisimiut, 66.93°N, 53.61°W, 18 Aug 2000, E. Horak (ZT8901, ZT8901), 50 m, with Salix glauca. N-Greenland: Daneborg, 0.5 km E of Airstrip, 74.2°N, 20.1°W, 29 Jul 2006, T. Borgen (TB06.033, C-F-119770), 20 m, with Dryas in heathland. Daneborg, slope NW of The Weather Station, 74.2°N, 20.1°W, 31 Jul 2006, T. Borgen (TB06.061, C-F-119769), 20 m, with Dryas sp. in heathland. Zackenberg, 74.5°N, 21°W, 3 Aug 2006, T. Borgen (TB06.081, C-F-119777), 50 m, with Dryas integrifolia and Dryas octopetala in scrubland. Zackenberg, 74.5°N, 21°W, 7 Aug 2006, T. Borgen (TB06.120, C-F-119765), 50 m, with Dryas in heathland. Zackenberg, 74.5°N, 21°W, 2 Aug 2006, T. Borgen (TB06.067, C-F-119743), 50 m, with Dryas sp. and Salix arctica in scrubland. Zackenberg, Aucellabjerg, 74.5°N, 21°W, 27 Jul 1999, T. Borgen (TB99.118, C-F-119756), 150 m, with Dryas sp. and Salix arctica in scrubland. Zackenberg, Aucellabjerg, 74.5°N, 21°W, 20 Aug 2006, T. Borgen (TB06.250, C-F-119764), 400 m, with Dryas sp., Bistorta vivipara and grassland. Zackenberg, Aucellabjerg, 74.5°N, 21°W, 9 Aug 2006, T. Borgen (TB06.128, C-F-119767), 300 m, with Dryas sp. in heathland. Zackenberg, Aucellabjerg, 74.5°N, 21°W, 11 Aug 1999, T. Borgen (TB99.280, C-F-119802), 150 m, tundra. Zackenberg, between West River and Solkæret, 74.5°N, 21°W, 9 Aug 1999, T. Borgen (TB99.258, C-F-119745), 30 m, with Dryas sp. and Salix arctica in scrubland. Zackenberg, just W of Kærelv, 74.5°N, 21°W, 30 Jul 1999, T. Borgen (TB99.160, C-F-119809), 30 m, with Salix arctica and Bistorta vivipara in solifluction lobe in snowbed. Zackenberg, shortly E of Kærelv, 74.5°N, 21°W, 13 Aug 1999, T. Borgen (TB99.304, C-F-119803), 50 m, with Dryas sp. in heathland. Zackenberg, Ulvehøj, 74.5°N, 21°W, 29 Jul 1999, T. Borgen (TB99.146, C-F-104296), 40 m, with Salix arctica in scrubland. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 8 Aug 2017, T. Borgen (TB17C.078, C-F-106777), 40 m, with Salix glauca in copse. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 7 Aug 2017, T. Borgen (TB17C.072, C-F-106776), 180 m, with Bistorta vivipara in heathland.

Distribution

One of the five most commonly recorded Hebeloma species in Greenland, with 11.6% of the records. Common and widespread in Europe; also recorded from other parts of North America (https://mycoportal.org/portal/collections/list.php, accessed 2 Dec 2020). To our knowledge not recorded from alpine sites in Europe (Beker et al. 2016).

Habitat and ecology

Forty-four collections, mainly with Salix glauca (15), Dryas (10) and S. herbacea (6). Minor hosts are S. arctophila and S. arctica, and two collections were difficult to separate from the roots of Bistorta vivipara. Found in all types of habitats from scrubland, grassland and heathland to snowbeds. In the Rocky Mountains, the hosts are S. arctica, S. glauca, S. planifolia, S. reticulata, Betula nana and Dryas (Cripps et al. 2019). For lowland Europe, there is a long list of deciduous trees as probable hosts (Beker et al. 2016).

Hebeloma sect. Velutipes Vesterh.; Ann. Micol. A. G. M. T. 1: 60, 2004

Stem velute, usually pruinose at least at apex, bulbous. Cheilocystidia gently clavate towards the apex, occasionally ventricose, spores rather strongly to very strongly dextrinoid.

Hebeloma leucosarx P.D. Orton; Trans. Br. mycol. Soc. 43(2): 244, 1960.

Fig. 32

Macroscopic description

Cap 1.8–9.0 cm in diameter, convex, later umbonate, sometimes turned upwards with age, margin often involute when young, later smooth or eroded or wavy, tacky when moist, rarely spotted, sometimes hygrophanous, usually bicolored, often with thin margin but may be unicolored when young, at center dark pinkish buff to ochraceous or dark olive buff or yellowish brown to clay buff or cinnamon to umber or brick, at margin cream to honey or pinkish buff to ochraceous or dark olive buff or clay-pink, without any remains of veil. Lamellae light gray brown to vinaceous buff, adnate to emarginate, maximum depth 2.5–9 mm, number of lamellae {L} 50–70, droplets usually visible but sometimes absent, white fimbriate edge present. Stem (3.0–)3.7–11.0 × 0.3–1.4 {median} × 0.8–2.0 {base} cm, stem Q (6–)6.8–14(–17.5), whitish, often clavate to bulbous, sometimes cylindrical, pruinose to floccose, particularly at apex, sometimes more velutinate, sometimes with mycelial chords. Context firm, stem interior hollow, sometimes with superior wick, flesh discoloring from base. Smell raphanoid, sometimes with hint of cacao. Taste raphanoid, sometimes weakly bitter. Spore deposit brownish olive to umber.

Figure 32. 

Hebeloma leucosarx A JV06-757 (from Denmark), photo J. Vesterholt, reproduced by kind permission from Beker et al. (2016) B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of TB81.211 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, occasionally limoniform, not or weakly papillate, on ave. 9.5–12.0 × 5.5–7.0 µm, ave. Q = 1.6–2.0 yellow brown to brown, guttulate, almost smooth to weakly ornamented but occasionally distinctly ornamented (O1 O2 O3), perispore not or somewhat loosening (P0 P1), weakly to strongly dextrinoid, reaction often very slow (D2 D3 (D4)). Basidia 24–33(–35) × 7–8(–10) µm, ave. Q = 3–4.1, mostly four-spored. Cheilocystidia slenderly clavate, occasionally clavate-stipitate or ventricose, occasionally with characteristic apical wall thickening, occasionally bifurcate, geniculate or septate, on ave. 41–67 × 6.5–8.5 (apex) × 4–5.5 (middle) × 4.5–6.5 (base) µm, ratios A/M = 1.42–1.72, A/B = 1.15–1.68, B/M = 0 .94–1.33. Epicutis an ixocutis, 80–200 thick (measured from exsiccata), maximum hyphae width 5 µm, sometimes encrusted, trama elements beneath subcutis ellipsoid to sausage-shaped, occasionally polygonal up to 20 µm wide. Caulocystidia similar to cheilocystidia, up to 200 µm long, often septate and markedly lageniform.

Collections examined

S-Greenland: Paamiut, head of Eqaluit, median part, 62.03°N, 49.25°W, 15 Aug 1998, T. Borgen (TB98.119, C-F-103513), 300 m, with Betula glandulosa and Salix glauca in heathland. Paamiut, Taartoq/Mørke Fiord, 62.01°N, 49.26°W, 29 Aug 1981, T. Borgen (TB81.211, C-F-103551), ca. 100 m, with Betula glandulosa in heathland.

Distribution

Only two records, both from the same area. The general distribution of the species is temperate, to the middle boreal zone. The Greenland records are both from low arctic areas. Hebeloma leucosarx is missing from lowland regions of southern Europe (Beker et al. 2016; Grilli et al. 2020).

Habitat and ecology

Among the 28 species of Hebeloma found in Greenland, H. leucosarx is the only species that may primarily be associating with Betula rather than Salix, based on the observations of Beker et al. (2016) from Europe. According to their monograph, in Europe, the main hosts are conifers and Betula (Beker et al. 2016); for the above records, the host is most likely B. glandulosa, although in one record S. glauca is mentioned as present.

Hebeloma subconcolor Bruchet; Bull. mens. Soc. linn. Lyon 39 (6 (Suppl.)): 127, 1970.

Fig. 33

Macroscopic description

Cap 0.8–2.1 cm, convex to umbonate, sometimes broadly, margin smooth, sometimes involute, tacky when moist, usually almost unicolored, at center clay buff to gray brown to dark olive buff to sepia, sometimes pruinose particularly when young, margin sometimes paler, even cream, veil absent. Lamellae when young whitish, later distinctly gray, adnate to emarginate, 3–4 mm broad, number of lamellae {L} 20–32, droplets usually visible with naked eye, but occasionally only with × 10 lens or absent, edge white fimbriate. Stem 1.5–4.5 × 0.3–0.6 cm, {median} × 0.35–0.75 {base} mm, velute, usually pruinose at apex, cylindrical, base clavate or sometimes bulbous. Context firm, in stem stuffed, later hollow, discoloring brownish from base. Smell raphanoid, sometimes strongly. Taste bitter, raphanoid. Spore deposit clay buff.

Figure 33. 

Hebeloma subconcolor A SAE-2016.090, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2016.090 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, limoniform, sometimes weakly papillate, on ave. 10.5–12.5 × 6.5–7.0 µm, ave. Q 1.6–1.85, usually guttulate, pale, yellow brown to brown, almost smooth to very weakly ornamented (O1 O2), perispore not or somewhat loosening (P0 P1), weakly to rather strongly dextrinoid (D2 D3). Basidia 26–33(–36) × 8–9 µm, Q = 3.4–3.9, mostly four-spored. Cheilocystidia slenderly clavate, sometimes cylindrical, clavate-lageniform or ventricose, occasionally with a characteristic apical wall thickening, occasionally bifurcate, geniculate or septate, on ave. 47–69 × 6.5–9 (apex) × 5–6.5 (middle) × 5–7.5 (base) µm, ratios A/M = 1.36–1.71, A/B = 1.22–1.86, B/M = 0 .92–1.26. Epicutis an ixocutis, 60–75 µm (measured from dried specimens), maximum hyphae width 5.5–6 µm, sometimes encrusted, shape of trama elements beneath subcutis ellipsoid, isodiametric, sausage-shaped up to 20 µm wide. Caulocystidia similar to cheilocystidia, up to 120 µm long and 11 µm wide, multi-septate.

Collections examined

S-Greenland: Kangilinnguit-Ivittuut, 61.21°N, 48.12°W, 18 Aug 2018, H. Knudsen (HK18.232, C-F-111111), 125 m, in tundra. Narsarsuaq, 61.17°N, 45.40°W, 17 Aug 2015, H. Knudsen (HK15.089, C-F-8242), 60 m, with Salix glauca. Nuuk, Qooqqut, 64.26°N, 50.92°W, 15 Aug 1987, T. Borgen (TB87.117, C-F-4002), ca. 30 m, with Salix glauca in ditch. Paamiut, 61.99°N, 49.66°W, 4 Aug 1993, E. Rald (ER 93.168, C-F-104313), 25 m. Paamiut, 62.01°N, 49.4°W, 14 Aug 1990, T. Borgen (TB90.033, C-F-104299), 25 m. Paamiut, N of the Navigation School area, 62.02°N, 49°W, 3 Aug 1990, T. Borgen (TB90.018, C-F-119761), ca. 40 m, with Bistorta vivipara and Salix herbacea. W-Greenland: Disko, Fortune Bay, 69.31°N, 53.88°W, 3 Aug 1986, T. Borgen (TB86.122, C-F-103587), 20 m. Sisimiut, south of town, 66.95°N, 53.66°W, 18 Aug 2016, S.A. Elborne (SAE-2016.090-GR, C-F-106739), 20 m, with Salix glauca in copse. E-Greenland: Jameson Land, Constable Pynt, Ugleelv, 70.88°N, 22.85°W, 24 Jul 1989, H. Knudsen (HK89.302, C-F-2195), 100 m.

Distribution

Hebeloma subconcolor is a truly arctic-alpine species with nine records from low and high arctic areas in Greenland. It was recently reported from two collections from alpine North America (Colorado, Cripps et al. 2019), but the records here are the first from arctic North America. Described from the European Alps by Bruchet 50 years ago, it is still only known from few other locations and it must be considered a rather rare species.

Habitat and ecology

Nine collections of H. subconcolor are verified, but only sparse info is given on hosts and ecology. Salix glauca, S. herbacea and Bistorta vivipara are mentioned as possible hosts. Most localities are on acid soil in agreement with the conclusion of Beker et al. (2016), who, in Europe, had S. herbacea listed as possible host for each cited collection of the species.

Hebeloma velutipes Bruchet; Bull. Mens. Soc. Linn. Lyon 39(6(Suppl.)): 127, 1970.

Fig. 34

Macroscopic description

Cap 1.6–8.2 cm in diameter, convex to umbonate, margin often involute when young, sometimes crenulate, occasionally upturned and wavy with age, tacky when moist, occasionally spotted, not hygrophanous, unicolored or variably bicolored, at center whitish to cream or buff to ochraceous or more rarely dark olive buff or yellowish brown or brownish olive, at margin white to cream or buff, without remains of veil. Lamellae clay brown, adnate to emarginate, occasionally with decurrent tooth, maximum depth 2–9 mm, number of lamellae {L} 50–78, droplets visible, occasionally only visible with × 10 lens, rarely absent, white fimbriate edge present, sometimes very distinct. Stem 0.5–10.4 × 0.3–1.6 {median} × 0.4–2.7 {base} cm, stem Q (0.6–)2.5–12.1(–14.4), whitish, base usually clavate to bulbous, sometimes cylindrical, usually velutinate, often pruinose or floccose at least on the upper half. Context firm, stem interior stuffed, later hollow, often with superior wick, occasionally with basal wick, flesh generally not discoloring from base. Smell usually raphanoid, sometimes earthy. Taste usually bitter and raphanoid. Spore deposit brownish olive to umber.

Figure 34. 

Hebeloma velutipes A SAE-2017.110, photograph S.A. Elborne B distribution of cited collections C spores ×1600 and D cheilocystidia ×1000 of SAE-2017.110 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, occasionally limoniform, variably papillate, but usually at most weakly, on ave. 9–13 × 5.5–7.5 µm, Q = 1.5–1.9, yellow through yellow brown to brown, usually guttulate, almost smooth to very weakly ornamented (O1 O2 (O3)), perispore not or somewhat loosening (P0 P1), rather strongly dextrinoid ((D2) D3 (D4)). Basidia 24–38(–43) × 6–10 µm, ave. Q = (3–)3.5–4.9, mostly four-spored. Cheilocystidia slenderly clavate, some clavate-lageniform, cylindrical or ventricose, more rarely clavate-stipitate, occasionally characteristically bifurcate, geniculate or septate (sometimes clamped), on ave. 43–73 × 6.5–9 (apex) × 4–6 (middle) × 4–7 (base) µm, ratios A/M = 1.31–1.73, A/B = 1.07–1.73, B/M = 0.86–1.34. Epicutis an ixocutis, 80–200 µm thick (measured from exsiccata), maximum hyphae width 4–8 µm, sometimes encrusted, trama elements beneath subcutis cylindrical, ellipsoid, isodiametric, sausage-shaped up to 12 µm wide. Caulocystidia similar to cheilocystidia, but more irregular, up to 200 µm long.

Collections examined

S-Greenland: Paamiut, 62.01°N, 49.4°W, 19 Aug 1998, T. Borgen (TB98.158, C-F-103512), 75 m, with Salix glauca in tundra. W-Greenland: Kangerlussuaq near the Ice cap, 67.10°N, 50.23°W, 12 Aug 2000, A-M. Larsen, T. Borgen (TB00.073, C-F-103519), 220 m, with Salix glauca in copse. Kangerlussuaq, airport area, 67.04°N, 50.41°W, 10 Aug 1986, T. Borgen (TB86.179, C-F-103557), 30 m, with Salix glauca and Betula nana. Kangerlussuaq, Ringsødalen, Kellyville, 66.99°N, 50.95°W, 14 Aug 2000, S.A. Elborne (SAE-2000.041-GR, C-F-108492), 180 m, at lakeside. Kangerlussuaq, Sandflugtsdalen, c. 15 km E of of the airport, 67.07°N, 50.46°W, 8 Aug 2016, T. Borgen (TB16.087, C-F-103582), 200 m, with Salix glauca and Sphagnum in scrubland. Kangerlussuaq, Store Saltsø, 66.99°N, 50.59°W, 15 Aug 2000, S.A. Elborne (SAE-2000.051-GR, C-F-108502), 260 m, with Betula nana in heathland. N-Greenland: Zackenberg, Aucellabjerg, at Kærelv, 74.5°N, 21°W, 14 Aug 1999, T. Borgen (TB99.336, C-F-119749), 100 m, with Dryas sp. and Salix arctica in scrubland. Zackenberg, W of Kærelv, 74.5°N, 21°W, 13 Aug 1999, T. Borgen (TB99.309, C-F-119754), 40 m, with Dryas sp. in scrubland. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 9 Aug 2017, H. Knudsen (HK17.186, C-F-105090), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.66°W, 6 Aug 2017, S.A. Elborne (SAE-2017.110-GR, C-F-106762), 65 m, with Dryas sp.

Distribution

Hebeloma velutipes is one of the most common Hebeloma species in Europe and widely distributed all over Europe (Beker et al. 2016). In Greenland, it is also widespread, but relatively uncommon. From alpine Europe it is known from the Pyrenees, the Alps and Lower Tatra, and from arctic Europe from Svalbard and Iceland (Beker et al. 2016). Outside Europe and Greenland, it is known from alpine sites in the Rocky Mountains (Colorado, Montana, Cripps et al. 2019).

Habitat and ecology

Ten collections, all but one (Paamiut) from calcareous localities. Salix glauca and Dryas are main hosts, one record is with Betula nana. In the Rocky Mountains, H. velutipes is also recorded with Dryas octopetala, Salix glauca and S. reticulata (Cripps et al. 2019). In Europe numerous hosts are recorded, see Beker et al. (2016).

Hebeloma sect. Naviculospora

Hebeloma islandicum Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 414, 2016.

Fig. 35

Macroscopic description

Cap 2.0–4.0 cm in diameter, convex to umbonate, margin involute when young, smooth, tacky when moist, not hygrophanous, uniformly colored or bicolored, at center dark olive buff to yellowish brown, at margin cream, innately fibrillose, sometimes with remnants of universal veil. Lamellae initially pale clay, in age often brownish, emarginate, maximum depth 5 mm, number of lamellae {L} 40–50, droplets visible with naked eye, with white fimbriate edge. Stem 1.7–2.5 × 0.4–0.6 {median} × 0.5–0.7 {base} cm, stem Q 3.4–5.5, whitish pale, finely flocculose-tomentose in the entire length with clavate base. Context firm, stem interior stuffed, later hollow, flesh usually discoloring from base. Smell raphanoid. Taste mild or slightly bitter. Spore deposit not recorded.

Figure 35. 

Hebeloma islandicum A TB19.81, photograph T. Borgen B distribution of cited collections; C spores ×1600 and D cheilocystidia ×1000 of TB86.291 in Melzer’s reagent. Scale bars: 5 µm; microphotographs H.K.J. Beker.

Microscopic description

Spores amygdaloid, often limoniform, papillate, on ave. 11.0–12.5 × 6.5–7.0 µm, ave. Q = 1.7–1.8, yellow to yellow brown, guttulate, at most weakly ornamented ((O1) O2), perispore not or somewhat loosening (P0 P1), weakly to rather strongly dextrinoid (D2 D3). Basidia 28–40 × 6–9 µm, ave. Q = 3.7–4.9, mostly four-spored. Cheilocystidia irregular, a mixture of clavate-stipitate, clavate-lageniform, ventricose and slenderly clavate, with occasional characters, geniculate, septate (sometimes clamped) or rostrate, on ave. 44–55 × 6.5–8.5 (apex) × 4–5 (middle) × 4–8 (base) µm, ratios A/M = 1.63–1.98, A/B = 1.04–1.85, B/M = 1.05–1.73. Epicutis an ixocutis, up to 120 µm thick (measured from exsiccata), maximum hyphae width 6 µm, some encrusted, trama elements beneath subcutis ellipsoid, cylindrical, thick sausage-shaped up to 20 µm wide. Caulocystidia irregular like cheilocystidia up to 140 µm long.

Collections examined

S-Greenland: Paamiut, N of town, 62.01°N, 49.4°W, 5 Sep 1986, T. Borgen (TB86.291, C-F-103573), 10 m, with Salix herbacea in snowbed.

Distribution

Only one record, from southern Greenland. Until recently only known from the type from the north-western, arctic part of Iceland. As discussed above, two more collections have been discovered from herbarium exsiccata at O; both, collected in Norway at above 60°N at altitudes of more than 1000 m (Eberhardt et al. in press). The above record from Greenland is from an arctic area and extends the distribution to North America. It is seemingly a very rare species. Although T.B. investigated the area around Paamiut regularly for 20 years, he only collected it once.

Habitat and ecology

All four known collections appear to have been associated with Salix herbacea in a wet snowbed.

Notes

Hebeloma islandicum was the only species recorded during the course of this study, which was not belonging to H. sects Denudata, Hebeloma or Velutipes. This species was described in Beker et al. (2016) on the basis of a single, but distinctive, collection from Iceland. The authors placed it within H. sect. Naviculospora. However, the authors acknowledged that it did not sit comfortably within any of their accepted sections. Within this section, this is the only species known to associate with Salix. Since its publication, two further collections have been discovered in Norway (Eberhardt et al. in press).

Molecularly, this species is unambiguous. The ITS of the collection presented here is almost identical with the ITS of the type (693/694 pos. identical, all positions are matching (one G/T in the type sequence matched by a clean G). Most similar, but always less than 98% similar, are H. naviculosporum and H. nanum (both H. sect. Naviculospora).

Discussion

This is the first monograph of Hebeloma in Greenland. With 381 analyzed collections (378 with ITS sequences) and 28 species, this is also the study encompassing the largest number of collections of this genus in Greenland. The sample includes one species new to science, H. arcticum, and collections of two species, H. islandicum and H. louiseae, that have previously been reported only from Iceland and Norway or Svalbard, respectively. Because of the inconsistencies in the application of names and interpretation of species that prevailed for a long time, we here ignore earlier works.

Much of Greenland is not easily accessible and the attention that different collection sites received is directly linked to their geographic setting, the available infrastructure and, last but not least, the biography of the main collectors. Thus, even the main collecting sites are not directly comparable: Paamiut, where T.B. lived for 20 years and Narsarsuaq, the airport which was the main access to Greenland for all collectors, were more heavily and frequently forayed than Zackenberg where T.B. collected for two seasons, and Jameson Land that was only visited in 1989 and 2017. It appears likely that this is the reason why Paamiut has the highest number of species and may be why three species (H. clavulipes, H. islandicum and H. leucosarx) were collected only there. While it cannot be claimed that this sample of collections is a truly random set, it is the case that the collectors did try to collect samples of every Hebeloma they noticed, and they did visit a number of different sites across Greenland, over some 40 years. So, it is likely to be a fairly representative sample of the sites visited at the time they were visited.

This paper follows earlier publications (Eberhardt et al. 2015a, b, 2016; Beker et al. 2016; Grilli et al. 2016; Cripps et al. 2019) in the delimitation of species. Thus, morphology (sometimes in combination with ecology) takes the lead in the delimitation of species in the absence of a clear molecular signal. This is done under the assumption that, if the species are truly distinct, then more in-depth molecular studies will reveal differences in future. If this were not the outcome, it would be much easier lumping species later than revisiting material later in order to separate taxa.

Greenland is rich in species that are difficult to delimit from one another and particularly rich with regard to members of H. sect. Hebeloma: we have not yet found a locus (or set of loci) that unambiguously separates between all species. Here, as in the species complexes around H. alpinum and H. velutipes, we do not expect the evolution to be treelike, thus network analyses are a viable option. The sequence data we have is from dikarya (earlier attempts to ‘phase’ dikarya failed in many cases), and intragenomic variation occurs regularly in many species. Intragenomic variation is difficult to process in networks and sequence “variants” represented by a single circle may in fact differ by ambiguous positions or through the presences of indels. The numbers of collections roughly doubled from the datasets used by Cripps et al. (2019) that were used as starting point for these analyses. Largely, the results obtained here support the results of Cripps and co-workers and, in most cases, the intraspecific variation or the lack of interspecific variation within Greenland matches that of the sequences from other parts of the northern hemisphere.

Notable exceptions are H. alpinicola, which, with Greenland samples included, and the number of collections increased, appears less clearly distinct from H. dunense than it did in the earlier study. Hebeloma helodes and H. aurantioumbrinum are also less distinct in their ITS in Greenland than they appeared in Cripps et al. (2019).

New additions such as H. arcticum, H. ingratum and H. louiseae are all clearly distinct from other species. For H. arcticum and H. louiseae this is also confirmed in the tree analysis. Hebeloma ingratum has close relatives (H. fragilipes and H. pseudofragilipes) that are not considered here. Apparent geographical structure in some of the networks, i.e. H. marginatulum, H. hiemale or H. velutipes, may include information with regard to the recolonization of Greenland after the last glaciation, but numbers are too low to draw any conclusions.

Beker et al. (2016) reported 25 species of Hebeloma that occur in arctic-alpine habitats of Europe, including Svalbard, out of 84 species for the whole of Europe. Five of the 25 species (H. aanenii, H. laterinum, H. pallidolabiatum, H. perexiguum and H. salicicola) have not yet been recorded in Greenland. With regard to H. pallidolabiatum and H. perexiguum, these species are, to date, only known from Svalbard and appear to be very rare. They may be endemic to Svalbard or simply not yet discovered in other areas of the Polar Regions. Three species, H. arcticum, H. colvinii, H. excedens, are currently only recorded from North America, including Greenland. Hebeloma alpinicola is described from North America, but was recently also found in Europe (Grilli et al. 2020). Also, a further four species, included here within the arctic funga of Greenland, are known from Europe but have never yet been recorded in arctic or alpine habitats. These are: H. clavulipes, H. helodes, H. hygrophilum and H. leucosarx. This means, that we now have 33 species of Hebeloma that have been recorded in arctic or alpine habitats.

Species of Hebeloma present in arctic and alpine habitats were classified by Beker et al. (2016) as “specialists” and “opportunists”. Specialists were defined as species that are widespread in such habitats, whereas opportunists are species that are more common in boreal habitats but are occasionally found in arctic and alpine habitats. Table 3 shows the classification into these two categories for the species confirmed for Greenland.

It is often impossible to remove ambiguous host information from collection metadata. Only in a few cases is a single host recorded as present. Further, if the collector is not aware of a potential host association, the person is likely not to record the presence of such hosts. A number of potential host genera and species have been named in different parts of this paper. While Salix appears to be the most common ectomycorrhizal host, there are cases, as noted above, when Dryas, rather than Salix, may be the symbiont; this appears to be the case, particularly in dry and calcareous localities and appears especially true for H. alpinum and H. hiemale, for which we have found Dryas to be the only or the closest possible symbiont on several occasions. Less frequently, we found Dryas as the likely symbiont for H. dunense, H. marginatulum, H. mesophaeum, H. pubescens, H. vaccinum, and H. velutipes. A few collections were made under Alnus alnobetulae ssp. crispa, but, in every case, other possible associates were almost certainly present. Also, a number of collections were made where Bistorta was the most likely symbiont.

We have no reason to assume that host associations of Hebeloma species are fundamentally different in Greenland from other arctic or alpine areas of the world. Sequences from root samples of B. vivipara from Svalbard suggested an association with members of H. sects Denudata and Hebeloma (Brevik et al. 2010, Beker et al. 2018). While all 25 arctic or alpine species discussed in Beker et al. (2016) appeared able to associate with Salix, that is not clearly true for the additional species recorded from Greenland. In particular, according to Beker et al., H. leucosarx appears to associate most commonly with Betula or conifers. However, this may be an exception, and, for the most part, sections of Hebeloma that do not include species associating with Salix, are lacking from Greenland. Thus, compared to Europe, the Greenland funga does not include any species of H. sects Duracinus, Myxocybe, Naviculospora (other than H. islandicum, which does not sit comfortably within that section), Porphyrospora, Pseudoamarescens, Scabripora, Sinapizantia, Syrjense or Theobromina. The only section that includes species associating with Salix (Beker et al. 2016) that has not been collected in Greenland, or other arctic areas, as far as we are aware, is H. sect. Sacchariolentia.

Hebeloma species associate with all important host groups in Greenland (Bistorta, Dryas and Salix) and MOTUs (molecular operational taxonomic units) assigned to the genus have been retrieved consistently in metagenomics studies of arctic or alpine habitats including these hosts, often among the more often retrieved ectomycorrhizal fungi (e.g. Bjorbækmo et al. 2010; Timling et al. 2012; Mundra et al. 2015; Morgado et al. 2016 and many others). It is often not possible to assign such MOTUs to species with any degree of certainty (Eberhardt et al. 2018), but it does appear that Hebeloma is one of the important players in the ectomycorrhizal communities of arctic habitats.

Acknowledgements

Borgen, Elborne and Knudsen received funding from Aage V. Jensen Foundation for expeditions to Greenland in 2016, 2017 and 2018 with the purpose of taking photos of arctic basidiomycetes for a forthcoming arctic-alpine funga, for which we are very grateful. A number of Danish and foreign colleagues placed their material at our disposal for which we are also grateful (see Material and Methods). Jan Vesterholt inspired and helped us with identifications at an early state of the research. Christian Lange at the Fungarium at The Natural History Museum of Denmark helped in various matters with the handling of the material. We also thank the numerous local helpers in Constable Pynt, in the Arsuk community and at Kangilinnguit, at the Zackenberg Research Station, at Daneborg and the Greenland Institute of Natural Resources in Nuuk and their field station in Kobbefjord. All this local help and kindness is necessary and greatly appreciated when working in these areas, which are difficult to access. We are very much obliged to A. Bogaerts and P. Ballings of the Botanic Garden Meise (BR) for help with handling various loans from a variety of herbaria. We are grateful to the reviewers and the editor for their efforts.

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