New records of lichenized and lichenicolous fungi in Scandinavia

Fourteen species of lichenized or lichenicolous fungi are reported new to either Norway or Sweden or both countries. Several of these are rare and almost unknown. The reported species are: Acarospora insignis (new to Norway), A. pyrenopsoides (Norway, Sweden), A. versicolor (Norway), Calvitimela perlata (Sweden), Lecidea degeliana (Sweden), Nephroma helveticum (Sweden), Peltula placodizans (Norway), Phacographa protoparmeliae (Norway), Rhizocarpon pycnocarpoides (Norway, Sweden), Sarcogyne algoviae (Sweden), Sarcogyne hypophaeoides (Norway, Sweden), Tephromela grumosa (Norway), Tremella lobariacearum (Norway) and Tremella wirthii (Sweden). In addition Cladonia albonigra is confirmed from Sweden. Sarcogyne hypophaeoides is lectotypified and is also reported new to Austria.


Introduction
Although studies of the biodiversity in Scandinavia have a long and continuous tradition, several thousands of species remain to be discovered, many of which are likely to be common.Among many of those discovered, almost nothing is known about where they occur, how they live and what their functional roles in the ecosystems are.To explore this poorly known biodiversity, the Swedish Taxonomy Initiative (STI) was established in 2002, with the aim to have all multicellular plants, fungi and animals in Sweden identified and described.Numerous taxonomic projects have been funded by the STI to investigate poorly known groups of organisms.Since 2002, almost 2000 species have been found new to Sweden and almost 1000 are new to science (Sundin 2014).In 2009, a similar project was established in Norway (the Norwegian Taxonomy Initiative, NTI), aimed at mapping all organisms in the country.Although the NTI does not provide funding for taxonomic research-projects, around 260 new species to science had been discovered in Norway until 2013 and the number of species new to Norway was approaching 1200 (http://www.artsdatabanken.no/Article/Article/133228).The two countries have signed a declaration of cooperation to increase the knowledge of and level of competence on biodiversity in Scandinavia, and collaborative projects have emerged.Several projects in both countries have focused on groups of lichenized and lichenicolous fungi, such as Acarosporaceae (funded by STI), lecideoid lichens (NTI, STI), Tremellales (STI), etc.During the last three years, lichen research groups in Oslo and Stockholm have collaborated and arranged workshops for lichenologists involved in these projects and beyond.Crustose, saxicolous lichens are in general very poorly known.Here, we add ten saxicolous lichens to the Scandinavian flora, mainly found in the still poorly investigated montane areas of Scandinavia.Also new macrolichens are continuously discovered in Scandinavia (Frödén 2010, Hultengren et al. 2011, Klepsland 2013, Klepsland and Timdal 2010) and here we report Nephroma helveticum new to Sweden, a rare and declining species in Europe that needs attention and possible conservation actions.In addition we confirm the presences of Cladonia albonigra in Sweden.Lichenicolous fungi are understudied and a lot of research is needed on this group (Ihlen and Wedin 2008).We have found three new species to the Nordic countries, one ascomycete, Phacographa protoparmeliae and two heterobasidiomycetes, Tremella lobariacearum and T. wirthii.These new records were collected during the last field seasons by some of the people involved in the different research projects funded by the STI and the NTI.

Material and methods
Material.We studied material collected during field surveys (2011)(2012)(2013)(2014) funded through STI and NTI projects as well as specimens of the same species on loan from various herbaria (GB, GZU, LD, O, S, STU, UPS).All specimens collected during these field trips are deposited in the herbaria O and S.
Morphology.Macromorphological traits were observed using a Zeiss Stemi 2000-C dissecting microscope.Microscopical examinations were carried out using squash preparations, hand-cut sections and freezing microtome sections cut at 16 μm.The preparations were observed in distilled water, lactophenol cotton blue, or 10% KOH (K).Microscopic structures in heterobasidiomycetes were studied using handmade sections stained with Phloxin (1% in water) after pre-treatment with KOH (5%), following the methods of Diederich (1996), and observed with a Zeiss Axioscope-2 microscope.Macro-and microscopic photographs were taken with a Nikon Coolpix 995 camera fitted to both microscopes or with a Nikon D300 with a macrolens with bellows.The macrophotos were processed using focus stacking with the programs Helicon Focus and Combine ZP.
Secondary chemistry.Selected specimens were examined by thin-layer chromatography (TLC), performed in accordance with the methods of Culberson (1972), as modified by Menlove (1974) and Culberson and Johnson (1982).
DNA barcoding.Some specimens (Table 1) were DNA barcoded for the nuclear ribosomal internal transcribed spacer region (ITS) through the Norwegian Barcode of Life project (http://www.norbol.org/)or projects funded by the STI.
Holotype.SWEDEN.Härjedalen: Viken.1878, P. J. Hellbom (GB 0129823!).TLC: gyrophoric acid.Distribution.New to Norway.This species has until now only been known from the type collection from central Sweden.Magnusson (1935) also mentioned a specimen from East Greenland.At first glance it appears to be an odd form of the common and well-known A. fuscata with pale brown to reddish brown areoles and a black lower surface that is typically spreading onto the edges of the upper surface (Fig. 1).The C+ red reaction of the cortex (gyrophoric acid) is also present in A. fuscata.However, the round, mostly scattered areoles with a single round apothecium and a very low hymenium, only between 50-65 μm tall, identifies A. insignis.A preliminary analysis of ITS sequences indicates that it is a close relative to the North American species A. thamnina (ID of specimens in GenBank of that species was confirmed by Kerry Knudsen, pers. comm.).
The Norwegian specimens were both collected on siliceous boulders in open spruce forests.The type specimen grows on Aspicilia cinerea and Magnusson (1924) concluded that it is a saprophyte.However, the newly found specimens do not grow in direct association with other species.Among other species seen in the specimens, Aspicilia cf.Distribution.New to Norway and Sweden.This is another poorly known species that has received very little attention since Magnusson (1926) discovered it.It has until now been known from scattered records from Greenland, Germany, Finland and Austria (Magnusson 1935, Wirth et al. 2013).It has also been reported from Denmark and Canada but those finds are considered erroneous (Søchting andAlstrup 2008, Knudsen andKocourková 2010).This is a characteristic species that has a thallus composed of rounded, fairly large squamules (fertile squamules 0.5-3 mm wide), with an incised or almost lobate margin (Fig. 2).The upper surface is flattened with a brownish grey colour.The lower side as well as the steep, vertical sides of the squamules are jet black and somewhat shiny.The apothecia are immersed, at first deeply sunken but later almost level with the thallus.The disc is brown, somewhat shiny and can become somewhat uneven in larger apothecia.Magnusson (1926) thought that the apothecia resembled those in certain species of Pyrenopsis from which the epithet is derived.The diagnostic characters include a thin poorly delimited cortex (10-15 μm), an uninterrupted algal layer, a tall (120-140 μm), euamyloid (I+ blue), hymenium and narrow spores (4-5 × 1.5 μm).Acarospora pyrenopsoides is a peculiar Acarospora not similar to any other species  in the genus.Magnusson (1926) considered its position in the genus to be isolated because of its unusual characters but speculated that it may be closest to A. nitrophila.The specimen from Norway was sequenced and a preliminary analysis (not shown) indicates that it belongs to a group with A. peliscypha, A. molybdina and A. wahlenbergii within Acarospora in a restricted sense (see Westberg et al. 2015).There is however, as far as we can see, no particular character of its morphology that indicates this relationship.
Acarospora pyrenopsoides appear to prefer humid localities.The locality in Norway reported here, lies near a waterfall where the species was found on sloping rocks.It is the only European site of the North American Rhizocarpon bolanderi (Tuck.)Herre, and was found during an inventory of that species.The two Swedish localities are located on or near lakeshores in the province of Värmland in central Sweden.
Specimens examined.Knudsen et al. in press).
Distribution.New to Norway.Acarospora versicolor is widespread on both siliceous and calcareous rocks in Europe and western Asia and is in the Nordic countries known from one locality in Finland and one unconfirmed report from Denmark (Alstrup et al. 1990, Knudsen et al. in press).
Acarospora versicolor belongs to the morphological group of brown Acarospora species lacking secondary metabolites.There are many names and many taxonomical problems in this group but A. versicolor was recently discussed and described in detail by Knudsen et al. (in press).Acarospora versicolor is identified by its white pruinose thallus and the negative C-reaction of the cortex.The thallus in A. versicolor is areolate and can become somewhat squamulose when well developed.It is mostly recognized by the presence of a white pruina on at least parts of the thallus (Fig. 3), but the pruina is sometimes lacking completely.The apothecia usually have a distinct margin and both the disc and the margin are typically darker than the thallus, sometimes almost black.It may then remind of a small form of A. badiofusca but the apothecia are not sessile as the mostly are in that species and there are several other character separating these species.
The Norwegian specimens reported here all grow calcareous rocks in sun-exposed habitats in the southern parts of the country.It is as far as we know the only one in this group of species in Scandinavia growing on calcareous rocks.However, elsewhere in Europe it also grows on non-calcareous rocks (Knudsen et al. in press).Distribution.New to Sweden.The species was previously known only from Norway and Greenland (Haugan and Timdal 1994).It resembles the more common C. aglaea (Sommerf.)Hafellner, but differs in forming white areolae (Fig. 4), slightly longer ascospores (11.5-17 × 5-7.5 μm; Haugan and Timdal 1994), and in the presence of rangiformic and norrangiformic acids in the thallus.In C. aglaea, the areolae are usually pale yellow, the ascospores shorter (9-13.5 × 5-7.5 μm), and the thallus contains atranorin, bourgeanic acid, usnic acid (rarely lacking), and sometimes stictic acid (Haugan and Timdal 1994).
In Norway, the species grows on sun-exposed, more or less sloping rock surfaces, often where water is trickling or near rivers or waterfalls in the subalpine and alpine regions.The Swedish locality is a boulder in the alpine region.
Distribution.Confirmed for Sweden.The species is reported from the province Torne Lappmark in northernmost Sweden by Ahti and Stenroos (2013), but no speci- men was cited and there are no specimens from Sweden in S or UPS.We here confirm its presence in Sweden and that province.The specimen (Fig. 5) was found on the same rock as Calvitimela perlata referred to above.Distribution.New to Sweden.Lecidea degeliana was described by Hertel (1970) from material collected by Degelius in northern Norway.Degelius himself (1982) reported a second find from the island of Vega in northern Norway but no further localities was mentioned by Hertel (1995) and we have not found any other literature reports of this species although collections have slowly been accumulating in the herbarium in Oslo.During an excursion to Sør-Trøndelag in Norway 2012, Swedish lichenologists had the opportunity to study the species in the field, and it was thereafter discovered in This small species may easily be overlooked or mistaken for a poorly developed L. fuscoatra.It is, however, a quite distinct species once discovered.The species is initially developing as a parasite on Acarospora spp.(Fig. 6).The thallus of L. degeliana is areolate, up to 3 mm wide, and frequently fertile with black, rounded or angular apothecia that are immersed in, or somewhat raised from the areoles; up to 0.2-0.6(-0.7)mm diam.In the microscope the apothecia have a greenish or bluish green hymenium, a black or greenish black epihymenium, and a dark brown hypothecium.The excipulum has a yellowish inner part, and the outer part is dark grey.The ascospores are ellipsoid-subglobose, 5.5-7 × 4-5 μm in the studied samples.The thallus contains the gyrophoric acid syndrome (Hertel 1995); thallus cortex in section K-, C+ red, excipulum in section K-, C-or C+ red.Hertel (1968) described Lecidea grummannii from Kärnten, Austria, another species growing parasitically on small brown Acarospora sp.That species is as far as we know only known from the type.According to Hertel (1995), L. grummannii differs from L. degeliana in having broader spores (5.2-5.5 vs 3.5-5.5 μm in L. degeliana), a paler hypothecium, (pale brown vs dark to blackish brown); a blue-green epithecium (vs olive-or greyish green in L. degeliana) and a paler thallus (cream coloured-whitish to beige vs beige to pale brown).In our experience of L. degeliana these characters are not so clear-cut and only the dark brown hypothecium seem to be a consistently different character compared to the description of L. grummannii.
Lecidea degeliana has mostly been found on calcareous rocks in exposed, subalpine habitats but also on siliceous and iron-containing rocks.There seem to be several different species of Acarospora involved as hosts but they are often sterile and mostly unidentified by us.They all belong to the small brown species of Acarospora s. str., and are in one case identified as A. versicolor through sequencing of the ITS and in another case tentatively identified morphologically as A. rugulosa.
Specimens examined.NORWAY.Hedmark: Ringsaker, the islet Holmen S of Helgøya in lake Mjøsa, 60°43'N, 11°01 'E, alt. 125-130 m. 11 Apr. 1982 Distribution.New to Sweden.Nephroma helveticum is a cosmopolitan species complex with a wide ecological amplitude and a large morphological and chemical variation.In Europe, however, the species is very rare and appears to have declined considerably (Klepsland 2103, James andWhite 1987).There are very few recent finds, among them a locality in Oppland in Norway, which is the first find in that country (Klepsland 2013).In the Nordic countries it is elsewhere known from a few old localities in Finland (Vitikainen 2007).Here we report it from one locality found in 2009 in Västerbotten and in addition we have found an old specimen in the herbarium in Stockholm from Västerbotten collected by Sten Ahlner in 1945 but never reported in the literature.The two localities are located 2.5 kilometers apart.We also report a second find of this species in Norway.The species is recognized by its tomentose lower surface without papillae (Fig. 7) and its chemistry of secondary metabolites, including the terpenoid T4 (James and White 1987).The most similar species N. resupinatum also has a tomentose lower surface but has white papillae between the tomentum and lacks secondary metabolites.One of the recently collected specimen from Västerbotten has been barcoded and the ITS sequence confirms the identity as N. helveticum.
On Ahlner´s locality, Borstaberget, the bedrock consists of greenstone (porphyrite) and the mountain has long southwest facing slopes with steep cliffs.Ahlner collected, together with N. helveticum, also the rare lichen Heterodermia speciosa.On the mountain Mitti-Skansberget N. helveticum was found in 2009 in two places 200 meters apart.It was found growing on conglomerate cliffs in the southwest facing precipices.Other species that were found on the cliffs were Peltigera rufescens, Lobaria scrobiculata, L. pulmonaria, Fuscopannaria leucophaea and Biatora vernalis.Distribution.New to the Nordic countries.The species is widely distributed in arid areas of both the Northern and Southern Hemispheres (Egea 1989).The nearest locality is found in Northern Italy (Vinschgau in South Tyrol; Buschardt 1979), and the species fits in the element of continental lichens with a widely disjunct distribution from the Alps to the upper valleys of southeast Norway.Other species with a similar disjunction include Buellia elegans Poelt, Gyalolechia desertorum (Tomin) Søchting et al., Psora vallesiaca (Schaerer) Timdal, Toninia sculpturata (H.Magn.)Timdal, T. taurica (Szatala) Oxner, T. tristis (Th.Fr.) Th.Fr., and Xanthocarpia tominii (Savicz) Frödén et al.The species is recognized by the crustose to subsquamulose, dark olivaceous brown thallus composed of areolae, which are up to 1 mm diam.and with marginal, black, granular soralia.The Norwegian material is sterile.The other Peltula species in the Nordic countries, P. euploca (Ach.)Poelt, differs in forming much larger, peltate squamules, up to 5 mm diam.The Norwegian specimen of Peltula placodizans is identified with some uncertainty, as the material for comparison (17 specimens from Europe, Africa, Australia, and North and South America, borrowed from GZU), was often more olivaceous brown than the dark brown Norwegian material (Fig. 8).Wetmore (1970) indicates that the species is probably a complex of several taxa.
Distribution.New to the Nordic countries.Phacographa was described by Hafellner 2009 who included three species in the genus.It belongs in the newly described family Lecanographaceae within the Arthoniales (Frisch et al. 2014).Phacographa protoparmeliae (Fig. 9) was originally reported from Austria and Spain (Hafellner 2009), and a specimen was later discovered in the Murmansk region in arctic Russia (Fryday 2011).Here we report it for the first time from the Nordic countries from two localities in Norway.Both are at old copper mines in subalpine habitats in the mining district of Røros in central Norway.
Phacographa protoparmeliae (Fig. 9) is a lichenicolous fungus growing on the common and widespread saxicolous lichen Protoparmelia badia.The apothecia of Phacographa have a black margin around a dark brown disc; they are up to 1.2 mm wide in the Norwegian material and form clustered groups of 2-6 apothecia.Microscopically it is characterized by its 3-septate, spores, 22-25 × 6-7(-8) μm that are colourless but have a perispore sheath that becomes brown with age.More detailed descriptions can be found in Hafellner (2009) and Fryday (2011).Holotype.CZECH REPUBLIC, Krkonoše Mts, "an den alten Bergwerken im Riesengrunde" (not seen).
Distribution.New to the Nordic countries.The species is apparently previously known only from the type locality in the Krkonoše Mts, where it was collected by Eitner about 1910 and by Kuťák in 1927.We have not seen the type material, but rather one duplicate of the material distributed by Kuťák in his exsiccate (Flechtensamml. Böhmen No. 520, O-L-184255).The species grows on rocks with a high content of iron and the thallus is rust coloured (Fig. 10).It resembles R. oederi (Weber) Körb., which may be found in the same localities, but differs primarily by forming larger ascospores (mainly muriform, 24-30 × 10-15 μm in R. pycnocarpoides vs. mainly 3-septate, 12-18 × 3-7 μm in R. oederi).Furthermore, the apothecia are more sessile, more regularly rounded, and with a thicker margin in R. pycnocarpoides, not in level with the areolae and angular to flexuouse as in R. oederi.An unpublished phylogenetic analysis of the genus Rhizocarpon  Holotype.[GERMANY, Bayern] Obere Seealpe in der Allgäuer Alpen bei Oberstdorf, c. 5000'.1860, H. Rehm (S L2741!).
Distribution.New to Sweden.This is a little known species rarely reported in the literature.Sarcogyne algoviae belongs to the morphological group in Sarcogyne with a strongly carbonized margin (Westberg et al. 2015).The apothecia vary considerably in size (0.3-1.8 mm) and has a raised, often glossy margin that is incised at short and fairly regular intervals (Fig. 11a, b) forming 5-15 segments.The disc is brown to dark reddish brown and often has one or two small carbonized accretions on the surface.Further characters include a euamyloid hymenium, 65-105 μm tall and narrow, 1-1.5 μm wide paraphyses, ellipsoid to narrowly ellipsoid spores, 2.5-4 × 1.5 μm and a colorless hypothecium (Fig. 11c).It can primarily be confused with S. clavus and S. hypophaea (syn.S. privigna, see Knudsen et al. 2013) but is apparently not closely related to either of these species (see phylogeny in Westberg et al. 2015).Sarcogyne clavus in its current sense (e.g.Magnusson 1935) always grows on siliceous rocks, has larger apothecia (up to 6 mm wide) with a margin that is irregularily cracked and crenulate and has a yellowish, to pale brownish hypothecium.Sarcogyne hypophaea grows on both siliceous and calcareous rocks and has generally smaller apothecia 0.3-0.7(1.3)mm, with a different appearance.The margin can be without or with rather indistinct incisions or with fewer (3-8) incisions at irregular intervals.
We have found Sarcogyne algoviae on several localities in Scandinavia, two in the continental parts of southern Norway and two in the Abisko area in northernmost Sweden.In addition we have found a few specimens from the Swedish mountains under the name S. clavus in the herbarium UPS.In all localities it grows on soft, calcareous schist in alpine-subalpine habitats.Sarcogyne algoviae is already included in the checklist for Fennoscandia, originally based on a specimen from Finnmark in northernmost Norway (Santesson et al. 2004).That specimen, however, has broadly ellipsoid spores and stout paraphyses, c. 2.5 μm wide, and belongs to Polysporina urceolata (specimen in Distribution.New to Norway, Sweden and Austria.Sarcogyne hypophaeoides has until now been known from the type material in central Finland and from one collection in Germany (Magnusson 1935).It is a characteristic but overlooked lichen that appears to be widespread in Scandinavia.The apothecia are 0.5-1.2mm wide, with a reddish brown to almost black disc sometimes with a central carbonized accretion.The margin is typically finely striated (Fig. 12a, b) and is softer and more leather-like in texture and not as strongly carbonized and brittle as the margin in e.g., S. clavus.The degree of carbonization varies however and in sections the central parts of the exciple may be rather weakly coloured (Fig. 12c).The hymenium is 70-90 μm tall and has a euamyloid reaction (I+ blue) and the spores are narrow and almost bacilliform, 3.5-5.5 × 1.0 μm.Sarcogyne hypopaheoides can mainly be confused with S. clavus or S. hypophaea but has a dark, brownish black to black hypothecium (Fig. 12c), which is a characteristic and diagnostic feature of this species.Sarcogyne clavus has a very uneven, cracked, crenulate margin and a yellowish to pale brown hypothecium.Sarcogyne hypophaea on the other hand, has a smooth margin, which usually appears segmented due to 2-3 deep incisions in the margin and a colorless hypothecium.
Sarcogyne hypophaeoides grows exclusively on siliceous rocks.We have found it on exposed, horizontal or sloping seashore rocks on the west coasts of Sweden and Norway, on lakeshores and on semi-exposed, vertical rocks or boulders in open coniferous forests.It is often growing with scattered apothecia on smooth rock surfaces or along cracks in the rock in a similar way to S. clavus and the two species have been found growing together on at least two localities.Difficulties to collect it and a superficial similarity to S. clavus are possibly reasons why this species has been overlooked.It appears to be fairly common in humid habitats in the boreal region of Fennoscandia but its distribution is incompletely known.
Distribution.New to Norway.Tephromela grumosa has been expected to occur in Norway, as it is known from a number of provinces in Sweden and Finland.It occurs in West, Central, and North Europe and in Asia (Lambley and Purvis 2009).The species is rather closely related to the type species of the genus, T. atra (Huds.)Hafellner & Kalb, but it is always sorediate and rarely fertile (Fig. 13).In contrast to the genetically very heterogenous T. atra s. lat., T. grumosa seem to be genetically rather consistent compared to its morphology (Muggia et al. 2008(Muggia et al. , 2014)).The species is furthermore separated by their chemistries, i.e., by the presence of lichesterinic acid in T. grumosa.The chemistry of the Norwegian specimen was confirmed by TLC.According to Muggia et al ( 2008) T. grumosa is a cooltemperate species found on steeply inclined, acidic siliceous rocks.In the locality in Norway, luxuriant, partly fertile specimens grew on steep faces of a large boulder in a stabilized S-facing talus.The rock is schistose, and probably somewhat calciferous.The locality is situated in one of the driest areas in Scandinavia, with an annual precipitation of c. 350 mm.In other habitats, e.g. on hard, granitic rocks in coastal heath on the Swedish west coast, specimens of this species are much thinner and less prominent.Distribution.New to the Nordic countries.Tremella lobariacearum was described by Diederich (1996) and is currently known from Africa (Ile de la Réunion), Asia (Japan, Philippines, and Russia), Europe (British Isles, France, and Portugal), Macaronesia (Canary Islands and Madeira), Oceania (Papua New Guinea) and South America (Bolivia, Colombia, Ecuador, and Peru), growing on Lobaria and Pseudocyphellaria species (Diederich 1996, 2003, van den Boom and Etayo 2000, Etayo 2002, 2010, Coppins et al. 2012, Flakus and Kukwa 2012).The species induces the formation of pale-brown to dark-brown galls on the isidia or soredia of the host (Fig. 14), or occasionally also directly on the thallus.The basidia are 2-celled.Two asexual morphs, consisting of lunate conidia and asteroconidia, are often found within the galls.Tremella lobariacearum is here reported from Norway and from the Nordic Countries for the first time, growing on Lobaria pulmonaria.The species is associated to habitats with high humidity and oceanic influence.The only specimen reported was collected, together with other non-infected L. pulmonaria thalli in an area with mixed and rich populations of Lobaria, in a Fraxinus-dominated open broad-leaved deciduous stand.
Tremella includes mainly mycoparasitic taxa that grow on a wide range of fungal hosts, including lichenized hosts.However, mycologists and lichenologists in general did not look much at the lichenicolous species until the first comprehensive study by Diederich (1996).Since then, several new species have been described (Diederich 2003, Sérusiaux et al. 2003, Diederich 2007, Zamora et al. 2011, Diederich et al. 2014, Millanes et al. 2012, 2014), and an increased interest has resulted in numerous new records, especially in the Nordic countries (Holien and Tønsberg 1994, Alstrup et al. 2004, 2008, Pippola and Kotiranta 2008, Westberg et al. 2008, Svensson and Westberg 2010, Knutsson and Johansson 2011, Millanes et al. 2014, Thell et al. 2014, Westberg and Thor 2014).Nevertheless, both the actual diversity and the distribution area of most species are still largely unknown.

Tremella wirthii Diederich, 1996
MycoBank: MB 415310 Tremella wirthii Diederich. Bibl. Lichenol. 61: 164. 1996. Holotype. GERMANY. Bayern: Neu-Ulm, Holzheim, Obstgarten WSW Steinheim, MTB 7626/2. 6 Feb 1991, V. Wirth 21713 (STU) Distribution.New to the Nordic countries.Tremella wirthii was described by Diederich (1996) based on material from four localities in Germany, growing on an unidentified sterile corticolous lichen.The host was later described as Protoparmelia hypotremella (Aptroot et al. 1997), a species similar to P. oleagina, from which it differs by its paler colour and its isidia-like granules.Both species are among the few corticolous Protoparmelia species, and grow on old wooden fences and buildings, and on deciduous and coniferous trees (Aptroot et al. 1997, 2001, 2004, Clerc 2004, Diederich and Sérusiaux 2000,   Scholz 2000, Hafellner and Türk 2001, Palice et al. 2006, van den Boom et al. 2007, Kubiak et al. 2010, Kukwa et al. 2012, Himelbrant et al. 2014).Aptroot et al. (1997) reported the presence of Tremella wirthii on specimens of P. hypotremella from Austria and the Netherlands.In the type locality of Protoparmelia hypotremella, in the Netherlands, T. wirthii was found both on P. hypotremella and P. oleagina.The three Scandinavian specimens grow on Protoparmelia oleagina.They were collected on wood of an old hay drying rack in the agricultural landscape of the Siljan Ring, an area with a calcareous bedrock, and the only locality in Sweden were P. hypotremella has been reported.Here, however, Tremella wirthii has not yet been found on that host.In the Nordic countries Protoparmelia oleagina occurs in Norway and Sweden (Nordin et al 2015).Tremella wirthii forms dark basidiomata, which are rarely bigger than 0.5 mm in diam., on the host thalli (Fig. 15a).Some micromorphological differences have been found between Swedish and Central European material.The specimens studied in the original description had 2-4 celled, longitudinally septate basidia, and no asexual morph was reported (Diederich 1996).The three specimens collected in Dalarna show typical basidia with 2 or 4 cells and longitudinal septa (Fig. 15b), but also basidia with oblique (Fig. 15c) or transverse (Fig. 15d) septa are present within the same basidioma.Moreover, in some cases there is an anamorph consisting of catenulate conidia (individual conidia 3-6 × 3-6 μm; Fig. 15e).Despite these differences, we consider the material from Sweden and Central Europe to be conspecific.The basidium morphology is extremely variable in many species of Tremella (Zamora et al. 2011, Millanes et al. 2012), and, when present, the occurrence of conidia is not constant in all specimens of the same species.Since the original description was based on four specimens only, the morphological variation within the taxon may well be greater than originally observed.Tremella wirthii is probably overlooked in Sweden, and additional field and herbarium surveys could reveal its presence in places were Protoparmelia oleagina is abundant.

Table 1 .
List of sequenced specimens with Accession numbers in the European Nucleotide Archive or GenBank.