Japan, Honshu, Gunma Prefecture, Katashina-mura, Nikko National Park, 4.7 km E of Marunuma Kogen Ski Resort, 550 m S of the parking lot at the start of the trail up to the summit of Mt. Oku-Shirane, along the trail. Open forest with mainly deciduous trees. On Tsuga diversifolia log. 36.81573°N, 139.37823°E (± 10 m), elevation 1791 m. 2019. Thor 40053 (Holotype UPS). DNA sample A914.

Figure 3. 

Morphological and anatomical features A, B Micarea eurasiatica sp. nov. (Thor 40053) A habit B apothecial section in water C, D Micarea melaeniza (Holotype) C habit, apothecia and pycnidia D apothecial section in water E–G Micarea nigella (Holotype) E apothecial section in K F apothecial section in water G drawing of M. nigella pycnidia on dead wood (Kantelinen 1974, H), Ga.) Mesopycnidia extruding mesoconidia, Gb.) Mesoconidia are cylindrical, ellipsoid, sometimes biguttulate. Photos and drawing Kantelinen. Scale bars: Habit 0.5 mm (A, C); Apothecial sections 100 µm (B, C, E, F); Drawing Ga 100 µm, Gb 1 µm.

Thallus endoxylic. Photobiont micareoid, 4–7 µm.

Apothecia few, immarginate, convex, black, matt, 0.1–0.2 mm in diam. Hymenium 25–40 µm tall, hyaline or tinged green, K+ greenish when tinged, sometimes with darker vertical streaks. Epihymenium black to blackish-green, K+ green, HNO₃+ purple (Cinereorufa-green). Asci clavate, 28–38 × 11–14 µm. Ascospores ellipsoid to ovoid, simple, (6–)7–9 × 3–4 µm. Paraphyses numerous, of two types: 1. evenly distributed, branched, thin, c. 0.7–1.5 µm wide, 2. evenly distributed, stout, sometimes branched, 2–3 µm wide, not always coated in pigment. Hypothecium c. 35–45 µm tall, dark brown, K – (Superba-brown), or sometimes with a slight purple tinge (Melaenida-red), hyphae coated with dark brown pigment. Excipulum not evident.

Mesopycnidia few to abundant, sessile to emergent, cylindrical in shape, 50–80(–100) µm tall, 30–45 µm wide, black, walls greenish black, K+ green, HNO₃+ purple (Cinereorufa-green), sometimes merged from base, usually extruding white mass of conidia that sometimes merge with neighbouring conidial mass. Mesoconidia ellipsoid-cylindrical, (4–)4.5–6.0 × 1.2–1.5(–1.8) µm. Micro- or macropycnidia not seen.

Chemistry. Material not sufficient for TLC.

Crystalline granules not present in apothecia or pycnidia.

M. eurasiatica is currently known from Finland and Japan. In Finland, the species was collected in a shaded and dense, Picea abies dominated managed forest. In Japan, the species occurred in a semiopen forest with mainly deciduous trees. On both occasions, the species was found growing on dead wood.

M. eurasiatica is currently known from two collections. The type collection has abundant mesopycnidia, and additionally few small apothecia. The other collection has only pycnidia. The most important diagnostic characters are the combination of sessile to emergent pycnidia that are cylindrical in shape, greenish-black pycnidial walls, large mesoconidia (up to 6 µm in length) and a K+ olive green reaction (Cinereorufa-green). If apothecia are present, they are 0.1–0.2 mm wide, have greenish-black epihymenium (K+ green, Cinereorufa-green) and dark brown hypothecium (K– or sometimes slightly K+ purple if Melaenida-red present). Micarea eurasiatica resembles other often asexual Micarea species on dead wood such as M. melaeniza, M. misella, M. olivacea and M. osloensis. Micarea eurasiatica differs from M. melaeniza by having shorter mesopycnidia, longer mesoconidia (M. melaeniza: (3–)3.5–4.5 × 1.2–1.8 µm, M. eurasiatica: (4–)4.5–6.0 × 1.2–1.5(–1.8) µm), and a more greenish black wall colouration in the pycnidia with no brown tones. Micarea misella has a K+ violet reaction (Sedifolia-grey) instead of K+ olive green and its mesopycnidia are brownish-black and taller (Coppins 1983; Czarnota 2007). Micarea olivacea has rather similar short mesopycnidia that react K+ green, but the wall of pycnidia is olive-brown and the mesoconidia are shorter than those of M. eurasiatica (M. olivacea: 3.4–4.3 × 1.2–1.6 µm, M. eurasiatica: (4–)4.5–6.0 × 1.2–1.5(–1.8) µm) (Coppins 1983). Micarea osloensis, on the other hand, has a warm brown wall colouration and usually no K reaction.

Finland, Uusimaa, Tuusula, W of Korso, shaded and dense Picea abies dominated managed forest (plot 2), on wood of fallen Picea abies (decay stage 2), 60.3544°N, 25.0322°E, 2013, Kantelinen 2729 (DNA A466), H.

Bih. Kongl. Svenska Vetensk.Akad. Hand. III, 18: 96 (1892). Type: Sweden, Helsinglandiæ [= Hälsingland], Jerfsö [= Järvsö], VIII 1891. J. T. Hedlund (S L1471! – lectotype, designated by Coppins 1983 [ICN Art. 9.10], further specified here [ICN Art. 9.17], S L1472!, UPS L-005556!, UPS L-171894!, LD 1056591!, isolectotypes).

Thallus endoxylic. Photobiont micareoid, 4–7 µm.

Apothecia absent to numerous (mostly rare), immarginate, subglobose, often becoming tuberculate, black, matt, 0.1–0.3 mm in diam. Hymenium (25–)28–42 µm tall, hyaline or tinged aeruginose green, olive, or rarely purplish brown, often with darker vertical streaks. Epihymenium irregularly pigmented aeruginose green, or rarely sordid brown, sometimes with a purplish tinge. Epihymenium and hymenium K+ olive green, HNO₃ purple (Cinereorufa-green), or rarely K–. Asci clavate, 22–35 × 10–12 µm. Ascospores ellipsoid to usually ovoid, simple, 5–9 × 2.5–4.0 µm. Paraphyses numerous, of two types: 1.) evenly distributed, branched, thin, c. 0.7–1 µm wide, 2.) scattered or in small fascicles, stout, c. 2 µm wide, coated by greenish pigment. Hypothecium c. 60–120 µm tall, dark brown (Superba-brown), sometimes greenish or with a reddish tinge, often K+ olive green in the upper part (reaction in the greenish Cinereorufa-green pigment), hyphae coated with dark brown pigment. Excipulum not evident.

Mesopycnidia always present, usually numerous, black, sessile or more usually stalked and then 80–300 µm tall, 40–70 µm in diam., stalks simple or branched from the base bearing up to four pycnidia, upper part of the walls greenish-brown and lower part reddish-brown, K+ dull green (the greenish pigment) or sometimes K–. Mesoconidia ellipsoid to short cylindrical 2.5–3.5 × 1.2–1.8 µm. Micro- or macropycnidia not seen.

Crystalline granules not present in apothecia, pycnidia or thallus.

Chemistry no substances detected by TLC (information based on Coppins 1983 and Czarnota 2007).

Typification. In his original description of Micarea melaeniza, Hedlund (1892) cited material that he had collected in Järvsö in Hälsingland, but without giving further specimen data. There are five specimens of M. melaeniza in S, LD and UPS collected by Hedlund in Järvsö in August 1891 and which all are likely to be part of the original material. Coppins (1983) cited a ‘holotype’ in S, which constitutes a lectotypification following ICN Art. 9.10. There is, however, an additional specimen in S (S L1472) with the same label data, and as Coppins (1983) did not indicate which of these specimens he considered to be the holotype, the lectotypification effectively concerns both specimens. We therefore further specify this by here designating the specimen S L1471 as the lectotype. This specimen was likely the one referred to as holotype by Coppins, as annotation slips from him are included in the envelope. It should be noted that all five type specimens of M. melaeniza are homogeneous.

M. melaeniza occurs on lignum of conifer stumps and logs. Based on sequenced specimens and type, the species is currently known from the Czech Republic, Finland, Sweden, Ukraine and the Russian Caucasus. In addition, M. melaeniza has been reported from Alaska (Spribille et al. 2020), Austria (Berger and Türk 1991, this study) and Mongolia (Palka and Śliwa 2006). Further, it might have been reported as M. nigella and could be found after revising specimens.

In his monograph of European Micarea species, Coppins (1983) accepted M. melaeniza, and in his interpretation, the species is characterized by having a hymenium with green pigmentation, a dark brown hypothecium without any reaction with K, and black stalked pycnidia containing comparatively short conidia. In the same work, the new species M. nigella was described, which should differ from M. melaeniza by having a purplish brown, K+ green pigment in the hymenium, hypothecium and pycnidial tissues, and slightly larger mesoconidia (M. melaeniza: 2.3–3.6 × 1–1.3 µm vs. M. nigella: 3.4–4.3 × 1.2–1.6 µm; Coppins 1983). Czarnota (2007) noted that the amount of purple, K+ green pigment varied considerably in Polish collections determined as M. nigella, and suggested that M. melaeniza and M. nigella could be conspecific. He further noted that Hedlund’s original description could be interpreted as indicating the presence of another pigment, the purple, K+ purple pigment and suggested that the differences between Hedlund’s and Coppins’ descriptions could be due to the studied material having aged (Czarnota 2007).

In our interpretation, M. melaeniza is a species with mostly two pigments: (i) a blackish-green, usually K+ green intensifying pigment, mostly located to the epihymenium but sometimes also in the hymenium and the upper part of the hypothecium (Cinereorufa-green) and (ii) a dark brown, K– pigment in the hypothecium (possibly Superba-brown). The description in Coppins (1983) fits our interpretation quite well, except that the specimens have a K+ greenish reaction due to Cinereorufa-green pigment that is not mentioned by Coppins (l.c.) but is, on the other hand, mentioned in the original description of the species by Hedlund (1892) and seen by us in the type specimen. Pigmentation of M. melaeniza may be more complex, however. One specimen from the Czech Republic (ZP32013) shows patchily purplish, K+ dark green pigment that might be the Melaena-red pigment (in apothecia concentrated mainly in hymenium as darker streaks). This specimen was originally downloaded to GenBank as M. nigella, but it is monophyletic with M. melaeniza in our phylogenetic analyses. More sequenced specimens are needed to understand better the pigment profile of M. melaeniza.

We considered the possibility of M. melaeniza and M. nigella being synonymous. A careful study of the type specimens showed morphological differences, e.g. in the size of conidia and pigmentation of apothecia and pycnidia. A brown or purple-brown, K+ green pigment in the hymenium, hypothecium and pycnidia walls (Melaena-red) of M. nigella is an important difference between M. melaeniza and M. nigella, although this is not true for all the studied specimens as was mentioned above. The difference in pigmentation is also visible in nitric acid, i.e. in M. melaeniza the hypothecium is mostly HNO₃– (rarely HNO₃ intensifying red), and in M. nigella HNO₃+ purple-red. Compared to M. melaeniza, M. nigella also has longer conidia (3.4–4.5 × 1.2–1.6 µm), slightly shorter hymenium (up to 30 µm) and wider paraphyses (up to 3 µm), as also shown by Coppins (1983).

The molecular study supports the distinction of M. melaeniza and M. nigella (Fig. 2). Our sequenced specimens form two monophyletic clades, and these specimens are morphologically similar with the type specimens (except for ZP32013 discussed above).

In external appearance, M. melaeniza also resembles M. botryoides, M. eurasiatica, M. misella and M. osloensis. Micarea botryoides is usually not lignicolous, has longer ascospores (8–13(–16) × 2.3–3.7(–4) µm) that are often septate, and longer mesoconidia (Coppins 1983). Micarea eurasiatica has similar pigmentation like M. melaeniza, but the shape of apothecia is different (adnate vs subglobose), its pycnidia are sessile and mesoconidia are longer (up to 6 µm). Micarea misella, on the other hand, can be microscopically distinguished from M. melaeniza by the olivaceous pigment that reacts violet instead of dull green in K, and by its hyaline hypothecium (Coppins 1983). Micarea osloensis is similar to M. melaeniza in many characters, and is a close relative based on our phylogenetic study. However, M. osloensis has shorter pycnidia (max. 180 µm), longer mesoconidia 3.5–4.5(–5) × 1.2–1.5 (–1.8) µm, and apothecia and pycnidia are mostly K– (although a higher concentration of Cinereorufa-green pigment is known to occur in some of the C-European specimens).

Austria, Niederösterreich, Ybbstaler Alpen, Wildnisgebiet Dürrenstein, Lunz am See Rothwald, Kleiner Urwald, primeval beech dominated forest on a crest above the valley of Moderbach brook, 47°46'31.0"N, 15°06'10.5"E, 1010 m, on wood of snag of Picea abies, 2022, Malíček 16229, Berger, Palice & Vondrák, hb Malíček.

Czech Republic, S Bohemia, Šumava Mts, Volary, České Žleby: Radvanovický hřbet - E foothill, managed spruce forest with left old beeches on E-NE-facing slope, 48°54'02"N, 13°48'28"E, on decaying wood of (?)Picea stump, 820 m, 2021, Palice 32013, PRA (in GenBank as M. nigella: OQ646318); ibid., Horní Vltavice, Zátoň: Jilmová skála Nature Monument, scree old-growth forest (150–200 years old) with maple, beech, sycamore, silver fir etc., 48°57'13"N, 13°47'48"E, 1000–1030 m, on decaying stump, 2014, Malíček 7322, hb Malíček.

Finland, Uusimaa, Vantaa, Herukkapuro nature reserve (plot 1), old-growth forest, on wood of a dead stump of Picea abies (decay stage 5), WGS84 60.3215°N, 24.7658°E, 2013, Kantelinen 2430 (DNA A772), H.

Ukraine, Ukrainian Carpathians, Nadvirna, Bystrytsia, in valley of stream Dzhurbzinets, c. 3 km south of village Maksymets, 48°28'30"N, 24°18'23"E, 1005 m, on soft wood of coniferous (Picea?) stump, 2019, Vondrák 21921, PRA.

Russia, Russian Western Caucasus, Adler, Krasnaya Polyana, primeval fir-beech forest below timberline, 43°41'50"N, 40°21'25"E, 1690 m, on soft rotten wood of Abies snag, 2019, Vondrák 23358, PRA.

Sweden, Ångermanland, Långsele par., VII. 1891. Hedlund, UPS (L-171893).

Thallus endoxylic or thin green-grey layer on top of substrate. Photobiont micareoid, 4–7 µm.

Apothecia absent to numerous (mostly rare), immarginate, subglobose, often becoming tuberculate, black, matt, 0.1–0.3 mm in diam. Hymenium 25–30 µm tall, hyaline or tinged dull brown or purplish brown, K+ sordid green, HNO₃+ purple-red (Melaena-red), often with darker vertical streaks. Epihymenium irregularly pigmented brown to purplish-brown (Melaena-red), sometimes dark greenish, K+ olive green, HNO₃+ purple (Cinereorufa-green). Asci clavate, 22–30 × 10–12 µm. Ascospores ellipsoid to usually ovoid, simple, 6.5–12 × 2.5–4.0 µm. Paraphyses of two types: 1.) evenly distributed, branched, thin, c. 0.7–1 µm wide, 2.) scattered or in small fascicles, stout, 2–3 µm wide, coated by dark pigment. Hypothecium c. 70–120(–160) µm tall, dark brown with variable amount of purplish tone, K+ olive green, HNO₃+ purple-red (Melaena-red), hyphae coated with a dark brown pigment. Excipulum not evident.

Mesopycnidia always present, usually numerous, black, sessile or more usually stalked and then 80–300 µm tall, 40–80 µm in diam., stalks simple or branched from the base bearing up to four pycnidia, walls brownish black to purplish black, sometimes olivaceous from the top, K+ dull green and HNO₃+ purple-red especially in the brown parts (Melaena-red). Mesoconidia ellipsoid or short cylindrical 3.5–4.5(–5) × 1.2–1.8 µm. Micro- or macropycnidia not seen.

Crystalline granules not present in apothecia, pycnidia or thallus.

Chemistry no substances detected by TLC (information based on Coppins 1983 and Czarnota 2007).

Micarea nigella occurs mainly on lignum of conifer stumps or fallen trunks, sometimes spreading from wood to dead bryophytes. Based on sequenced specimens and the type material, the species is known from the Czech Republic, Denmark (holotype), Great Britain (paratypes), Finland and Sweden. In addition, M. nigella has previously been reported from boreal and temperate forests in north-western, central and eastern Europe (e.g. Czarnota 2007).

In external appearance, M. nigella resembles M. melaeniza. The differences between these two species are discussed in detail under M. melaeniza and Coppins (1983). The species also resembles M. botryoides, M. misella and M. osloensis. Micarea botryoides is usually not lignicolous and prefers rain-sheltered microhabitats on various substrata, it has slightly taller pycnidia (up to 400 µm) and longer ascospores (8–13(–16) × 2.3–4 µm) that are often septate (e.g. Coppins 1983). Microscopically, M. misella can be distinguished by the olivaceous pigment that reacts violet instead of dull green in K, and by its hyaline hypothecium (Coppins 1983; Czarnota 2007). Micarea osloensis, on the other hand, is usually K– and its pycnidia are shorter. However, our study includes specimens that are difficult to identify by morphological characters, especially between M. melaeniza, M. nigella and M. osloensis.

One of the distinguishing characteristics of M. nigella is the Melaena-red pigment (K+ green, HNO₃+ purple-red) in the hymenium, hypothecium and pycnidia. In the literature, the pigment is described as `purple` (Coppins 1983; Meyer and Printzen 2000; Czarnota 2007). However, based on our study, the pigment is mostly brown, sometimes with a purplish tinge. The holotype of M. nigella has the Melaena-red pigment, that looks brown with a purplish tinge, but of our three sequenced specimens (Fig. 2, Table 1), one (collection Kantelinen 1971) has no purplish tone, whereas the other two collections (Kantelinen 1974, 1921) have easily detected amounts of purple. Interpreting the colouration can be difficult and confusing, but maybe a helpful hint is that the pigment is always K+ green, even if it looks brown in water. According to our study, the K+ green reaction mostly disappears in 30 minutes.

Occasionally, M. nigella also has a third pigment, the Melaenida-red (K+ purple). This pigment was not found in the Finnish specimens but is sometimes seen in the Central European specimens included in this study and mentioned also by Coppins (1983) and Czarnota (2007). The Melaena-red and Melaenida-red pigments can be intermixed and appear in varying concentrations.

Czech Republic, Central Bohemia, Brdy Protected Landscape Area, Míšov, Na Skalách Nature Reserve, old-growth beech forest, small scree with rock outcrops and sparse spruce forest in NW part of the protected area, 49°36'20"N, 13°45'56"E, 715–740 m, on stump, 2023, Malíček 16287, hb Malíček. Western Bohemia, Domažlice, Český les Protected Landscape Area, Pec, Bystřice Nature Reserve, natural mixed forest up to 150 years old, 49°22'56"N, 12°48'39"E, 650–750 m, on lying decaying trunk, 2015, Malíček 8029 (hb Malíček); ibid., Tachov Lesná: managed spruce forest 1 km NE of Knížecí strom Hill (829 m), 49°46'13.0"N, 12°29'28.3"E, 750 m, on stump of Picea abies, 2019, Malíček 13161 & Rydlo, hb Malíček. Southern Bohemia, Prachatice, Šumava National Park, Nová Pec old-growth beech-spruce forest on N-facing slope of Mt Hraničník (1281 m), 48°45'13"N, 13°54'17"E, 1170 m, on decaying wood, 2017, Malíček 11296, hb Malíček. Eastern Bohemia, Žďár nad Sázavou, Žďárské vrchy Protected Landscape Area, Svratka managed beech-spruce forest on NW-facing slope of Bubnovaný kopec Hill (780 m), 49°42'41.6"N, 16°05'13.7"E, 775 m, on stump of Picea abies, 2020, Malíček 13865 & Sejfová, hb Malíček. Svratka forest mosaic 0.2 km SSE of Spálený kopec Hill (766 m), 49°43'28.0"N, 16°06'23.3"E, 755 m, on stump of Picea abies, 2020, Malíček 13868 & Sejfová, hb Malíček. Svitavy, Česká Třebová, Psí kuchyně Nature Reserve, old-growth beech forest 0.1 km NW of Psí kuchyně Hill (526 m), 49°50'38.3"N, 16°26'47.5"E, 505 m, on lying wood of Fagus sylvatica, 2020, Malíček 13975 & Rydlo, hb Malíček. Silesia, Beskydy Protected Landscape Area, Horní Lomná, Velký Polom Nature Reserve, valley of a brook with old-growth, beech predominated forest in the E part of the protected area, 49°30'36"N, 18°41'00"E, 860–910 m, on stump of Picea abies, 2021, Malíček 14664 & Sejfová, hb. Malíček; ibid., gorge on NW-facing slope of Mt Velký polom (1067 m), c. 49°30'25"N, 18°40'04"E, 950–1000 m, on stump, 2021, Malíček 14649, Hlisnikovský & Sejfová, hb Malíček; ibid., Karolinka, Malý Javorník Nature Reserve, old-growth spruce-beech forest, 49°18'20.9"N, 18°17'18.5"E, 880–970 m, on wood of stump, 2023, Malíček 16392, hb Malíček; ibid., Valašská Bystřice, Kutaný Nature Reserve, old-growth beech-silver fir forest, 49°22'15.6"N, 18°6'0.4"E, 610–770 m, on fallen wood, 2020, Malíček 14246 & Konečná, hb Malíček. Jeseníky Protected Landscape Area, Karlova Studánka, old-growth spruce forest on SE-facing slope in valley of Bílá Opava Brook, along tourist path 1.1 km NE of Ovčárna, 50°04'37"N, 17°15'06"E, 1170–1200 m, on roots of Picea abies, 2015, Malíček 8547, hb. Malíček.

Finland, Pohjois-Karjala, Lieksa, Koli National Park (plot 9), East side, old-growth forest, on wood of fallen Picea abies (decay stage 2), 63.1033°N, 29.8140°E, 2013, Kantelinen 1971 (DNA A589), H; ibid., Kantelinen 1974 (DNA A588), H; ibid., Kantelinen 1921 (DNA A572), H. Etelä-Häme, Hämeenlinna, Evo (plot 8), protected old managed forest, on wood of a Picea abies stump (decay stage 5), 61.2088°N, 25.1363°E, 2013, Kantelinen 2851 (DNA A769), H; ibid., Kantelinen 2881 (decay stage 4, DNA A764), H.

Slovakia, Eastern Slovakia, Bukovské vrchy Mts., Nová Sedlica, protected area Stužica, NNE-facing slope of Temný vršok Mt. (838 m), old-growth beech forest, 49°04'11"N, 22°32'26"E, 750–820 m, on stump of Abies alba, 2013, Malíček 6511 & Vondrák, hb Malíček.

Bih. Kongl. Svenska Vetensk.Akad. Hand. III, 18: 97 (1892). Lecidea osloensis Th. Fr. Lich. Scand. 2: 524 (1874). Type: Norway, Oslo, In cacumine Ryenbjerget, 10 July 1874. N.G. Moe (UPS L-153276! – holotype).

Figure 4. 

Morphological and anatomical features of old and new Micarea osloensis collections A, B old Micarea osloensis A habit, apothecia on soil (Holotype) B apothecial section in water (Palice 11684, H) C–E new Micarea osloensis (Kantelinen 2648, H) C mesopycnidia extruding mesoconidia as a white drop D apothecial section in water E mesopycnidia on dead wood and mosses. Scale bars: Habit 0.5 mm (A, C, E); Apothecial sections 100 µm (B, D).

Thallus endoxylic or visible as a thin pale greenish-grey to dark green-grey layer on top of substrate. Photobiont micareoid, 4–7 µm in diam.

Apothecia infrequent or rare, absent or numerous, immarginate, convex to hemispherical, dark brown to black, matt, simple, 0.1–0.2(–0.3) mm in diam. Hymenium 30–50 µm tall (Coppins c. 30 µm tall), hyaline, sometimes olivaceaous, often with warm brown vertical streaks, K–, HNO₃– (Superba-brown). Epihymenium warm dark brown to blackish (Coppins: red-brown), rarely greenish, mostly K– but sometimes K+ green, HNO₃– or HNO₃+ purplish (Cinereorufa-green). Paraphyses of two type: 1.) hyaline or coated with a brown pigment, thick, 2–3 µm wide, simple or branched, sometimes wider from apices, often uneven in shape, abundant, sometimes concentrated into fascicles, 2.) thinner, c. 1–1.5 µm wide, rarely branched, rare. Asci cylindrical to cylindrical-clavate, 30–40 × 10–12 µm (Coppins: 26–30 × 11–13 µm). Ascospores 7–10 × (2.5–)3.0–3.5 (–4.0) µm (Coppins: 6–9.5 × 3–4 µm), ellipsoid, cylindrical or sometimes roughly shaped, 0(–1) sept. Hypothecium warm dark brown (Coppins: red-brown), composed of hyaline hyphae 1–2 µm wide surrounded by brown pigment giving it an unevenly coloured/randomly spotted appearance, K–, HNO₃– (Superba-brown), c. 85 µm tall.

Mesopycnidia often numerous and crowded, sometimes absent, simple or branched from the base, emergent or shortly stalked ca. 50–180 µm tall, 40–70 µm in diam., dark brown to blackish, walls brown, greenish brown from the top with a warm brown lower part, K– (Superba-brown) or sometimes K+ green, HNO₃– or HNO₃+ purplish (Cinereorufa-green), usually extruding white mass of conidia that may merge with neighbouring conidia. Mesoconidia ellipsoid or short cylindrical 3.5–4.5(–5) × 1.2–1.5 (–1.8) µm. Micro- or macropycnidia not seen.

Chemistry no substances detected by TLC (Coppins 1983).

Crystalline granules not present in apothecia, pycnidia or thallus.

The type of M. osloensis occurs on soil. Another morphologically identical specimen collected in 2007 occurs on bark of decaying trunk (Palice 11684). Our newer specimens occur on bark, dead wood and dead mosses. The type specimen was collected from Norway from a woodland clearing on the site of an old bonfire, and the newer specimens are from the Czech Republic, Finland, Sweden and Ukraine. In the Czech Republic, M. osloensis occurs commonly from middle to montane elevations. It appears to be toxitolerant and is known in areas with higher levels of air pollution in the past (i.e. acidification by acid rain). The typical habitats are bark on bases and roots of Fagus sylvatica, Larix decidua, Picea abies, Pinus sylvestris. It is abundant also on dead wood and dead bark on stumps, fallen trunks and snags. In Finland, M. osloensis is likely relatively common but overlooked in coniferous forests on bark, dead wood and dead mosses. In both countries, M. osloensis is known from managed and old-growth forests.

The two previously known M. osloensis specimens, including the type, have not been sequenced, although an unsuccessful sequencing attempt of a specimen collected by Palice (11684) was made by Kantelinen in 2011, and therefore we cannot compare our new specimens to the type of M. osloensis using DNA. Subtle morphological features differentiate the type from new specimens, i.e. taller hymenium and asci. Most of the new specimens are K– and have only the Superba-brown pigment, similar to the type. However, some specimens have a K+ greenish, HNO₃+ purple reaction in the epihymenium and pycnidial walls suggesting the presence of the Cinereorufa-green pigment which is not known from the type of M. osloensis. Specimens with the Cinereorufa-green pigmentation appear to be more frequent in the Czech Republic. The Finnish specimens have sometimes olivaceous tones that are K– but slightly HNO₃+ purple.

Another difference between the type of M. osloensis and our newly sequenced specimens is reproduction. The type specimen has apothecia and no pycnidia. The new specimens, on the other hand, often have shortly stipitate pycnidia. Our specimens appear to be dimorphic, however, so that the specimens represent either sexual (rare) or asexual reproduction modes which are monophyletic in DNA level.

Because of overlapping variation in reproduction and pigmentation between the type of M. osloensis and our new specimens, we cannot exclude the possibility that they are conspecific. On the other hand, we also cannot exclude the possibility that the new specimens represent a yet undescribed taxon in the M. melaeniza group.

M. osloensis resembles M. eurasiatica, M. melaeniza, M. misella and M. nigella. The most important characters of M. osloensis are the combination of sessile to shortly stalked pycnidia, mesoconidia of the size 3.5–4.5(–5) × 1.2–1.5 (–1.8) µm, warm-brown, sometimes olivaceous colouration in apothecia and pycnidia (Coppins: red-brown), and often a K– reaction. Micarea eurasiatica sp. nov. has mostly sessile to emergent pycnidia and bigger mesoconidia ((4–)4.5–6.0 × 1.2–1.5(–1.8) µm). Micarea misella, on the other hand, has a K+ violet reaction in the epihymenium and pycnidia (Coppins 1983; Czarnota 2007). Micarea nigella has similar mesoconidia and spore size, but its pycnidia are usually taller and it has the brown/purple-brown Melaena-red pigment (K+ green) in hypothecium and pycnidia.

Based on our phylogenetic analyses, M. osloensis and M. melaeniza are sister species. They have morphological similarities including pigmentation and spore size. However, M. osloensis has slightly larger mesoconidia, shorter pycnidia and wider often roughly shaped paraphyses. The concentration of the Cinereorufa-green pigment (K+ green, HNO₃+ purple) appears to vary in both taxa, but especially in M. osloensis. Micarea melaeniza is mostly K+ green in epihymenium, hymenium, upper hypothecium and pycnidia. Micarea osloensis, on the other hand, is rarely K+ green and then from the epihymenium and pycnidia.

Czech Republic, Northern Bohemia, Jizerské hory Mts, Josefův Důl: valley of Jedlový potok, protected zone of nature reserve Jedlový důl, fragment of fir-beech old-growth forest, 50°47'45"N, 15°14'47.5"E, on dry wood of old conifer stump, 780 m, 2020, Palice 30266, PRA (in GenBank as M. nigella: OQ646320); ibid., Hejnice, Jizerskohorské bučiny National Nature Reserve, valley of Velký Štolpich brook, S of Ořešník Mt. (800 m), ca 50°51'13"N, 15°11'13"E, 660 m, on base of Fagus sylvatica, 2013, Malíček 6020, hb Malíček. Lužické hory Protected Landscape Area, Mařenice, Horní Světlá: managed spruce-beech forest on E-facing slope, 0.3 km NNW of Kopřivnice Hill (638 m), 50°50'13.6"N, 14°37'56.6"E, 600 m, at base of Picea abies, on stump of Picea, 2020, Malíček 14019, 14020 & Rydlo, hb Malíček. Central Bohemia, Brdy Protected Landscape Area, Míšov, Na Skalách Nature Reserve, old-growth beech forest, small scree with rock outcrops and sparse spruce forest in NW part of the protected area, 49°36'20"N, 13°45'56"E, 715–740 m, at base of Fagus sylvatica, 2023, Malíček 16281, hb Malíček. Brdy Hills, Rožmitál pod Třemšínem, Nepomuk: managed forest 0.4 km N of Praha Hill (862 m), 49°39'48"N, 13°49'06"E, 825 m, at base of Larix decidua, 2018, Malíček 12007 & Vondrák, hb Malíček; ibid., Strašice, managed mixed forest 3 km E of village, 49°43'34"N, 13°47'56"E, 610 m, at base of Larix decidua, 2018, Malíček 12000 & Vondrák, hb. Malíček. Příbram, Brdy Hills, Jince managed coniferous forest 0.5 km SSE of Velcí pond, 49°45'17"N, 13°56'34"E, 600 m, at base of Larix decidua, 2018, Malíček 12016 & Vondrák, hb Malíček. Eastern Bohemia, Rychnov n. Kněžnou, Orlické hory Protect. Lands. Area, Rokytnice v Orlických horách, Černý důl Nature Reserve, fragment of old-growth beech-spruce-silver fir forest, along brook, 50°12'01.4"N, 16°31'18.2"E, 800–810 m, on bark of stump of Picea abies, 2012, Malíček 4536 et al., hb Malíček. Žďár nad Sázavou, Žďárské vrchy Protected Landscape Area, Svratka fragment of old beech predominated forest 0.6 km SW of Spálený kopec Hill (766 m), 49°43'18.2"N, 16°06'11.4"E, 750 m, on stump of Picea abies, 2020, Malíček 13864 & Sejfová, hb Malíček; ibid., Svratka, Pustá Rybná: spruce-beech forest on S-facing slope of Kaštánkův kopec (753 m), 49°43'03.9"N, 16°06'46.4"E, 740 m, on stump of Picea abies, 2020, Malíček 13953, hb Malíček. Svitavy, Česká Třebová managed spruce forest 3 km W of Opatov, 49°49'47.6"N, 16°27'40.0"E, 445 m, on stump of Picea abies, 2020, Malíček 13970 & Šámalová, hb Malíček. Western Bohemia, Český les Protected Landscape Area, Tachov, Lesná: young beech forest 0.8 km E of Knížecí strom Hill (829 m), 49°45'54.2"N, 12°29'18.5"E, 780 m, on stump of Picea abies, 2020, Malíček 13784 & Rydlo, hb Malíček; ibid., spruce-beech forest 1 km NE of Knížecí strom Hill (829 m), 49°46'17.3"N, 12°29'18.1"E, 770 m., at base of Picea abies, 2019, Malíček 13167 & Rydlo,hb Malíček; ibid., Pec, Bystřice Nature Reserve, natural mixed forest up to 150 years old, 49°22'56"N, 12°48'39"E, 650 m, at base of Picea abies, 2015, Malíček 8028, hb Malíček. Kdyně, Mezholesy: managed mixed forest 0.3 km SE of Koráb Hill (773 m), 49°23'37.7"N, 13°04'44.1"E, 750 m, at base of Picea abies, 2019, Malíček 13371 & Rydlo, hb Malíček. Southern Bohemia, Novohradské hory Mts, Horní Stropnice, NPP Hojná Voda, fragment of primeval forest predominated by beech, 48°42'20"N, 14°45'08"E, 840–870 m, on snag, 15 October 2019, Malíček 13500, herb. Malíček. Šumava Mts., Volary, Nová Pec, 740 m, 48°49'11.2"N, 13°56'12.151"E, on bark of Pinus sylvestris at base of trunk, 2017, Vondrák 19007, PRA. Prachatice, Šumava Protected Landscape Area, Kubova Huť, Boubínský prales National Nature Reserve, managed spruce forest c. 120 years old, 0.4 km NNE of top of Mt Boubín (1362 m), 48°59'42.2"N, 13°49'05.7"E, 1275 m, on decaying stump 2015, Malíček 8349 & Palice, hb Malíček. Jindřichův Hradec, Javořická vrchovina Hills, Stráž nad Nežárkou, Sedlo: managed coniferous forest SSE of Otínský kopec Hill (538 m), 49°02'44.0"N, 14°59'45.7"E, 530 m, on stump, 2020, Malíček 13817, hb Malíček; ibid., Lásenice: mixed forest S of Šemburský rybník, 49°03'34.6"N, 14°59'55.2"E, 520 m, on stump, 2020, Malíček 13821, hb. Malíček; ibid., managed coniferous forest between Nová Ves and Sedlo, 49°03'36.1"N, 15°00'55.3"E, 560 m, at base of Pinus sylvestris, 2020, Malíček 13824, hb Malíček. Tábor Chýnov, young beech forest SSE of Blanička, 49°28'00.6"N, 14°50'34.9"E, 690 m, on fallen wood, 2020, Malíček 13834 & Rydlo, hb Malíček; ibid., mixed forest SE of Batkovy Hill (724 m), 49°27'43.3"N, 14°50'00.9"E, 700 m, at base of Larix decidua, 2020, Malíček 13838 & Rydlo, hb Malíček. Northern Moravia, Jeseník, Jeseníky Protected Landscape Area, Bělá pod Pradědem, Vysoký vodopád, Nature Reserve, valley of Studený p. brook, ca. 50°06'57"N, 17°12'10"E, 900–1000 m, on base of Picea abies, 2012, Malíček 5102, hb Malíček. Šumperk, Králický Sněžník Mts, Staré Město: Mt. Králický Sněžník, c. 100 years old spruce forest on S-facing slope 0.1 km SE of Františkova chata, 50°12'05.2"N, 16°51'28.3"E, 1210 m, at base of Picea abies, 2015, Malíček 8381, Kocourková & Vondrák, hb Malíček. Eastern Moravia, Beskydy Protected Landscape Area, Bílá, Salajka: beech dominated forest 0.6 km SE of gamekeeper’s house, 49°24'37.9"N, 18°25'39.5"E, 730 m, on decaying stump, 2019, Malíček 13344 & Rydlo, hb Malíček; ibid., Frenštát pod Radhoštěm, Kněhyně-Čertův mlýn National Nature Reserve, W-facing slope of Kněhyně Mt. (1257 m), old-growth spruce forest above red-marked tourist path, 49°29'57"N, 18°18'38"E, 1080–1100 m, on stump of Picea abies, 2013, Malíček 6090 & Vondrák, hb Malíček. Western Moravia, Žďár nad Sázavou, Žďárské vrchy Protect. Landsc. Area, Cikháj, Žákova hora National Nature Reserve, beech virgin forest, 49°39'18"N, 15°59'35"E, 750–800 m, on stump of Fagus, 2012, Malíček 5110 & Syrovátková, hb Malíček. Silesia, Bruntál, Jeseníky Protected Landscape Area, Karlova Studánka, managed spruce forest (c. 100 years old) on N-facing slope in valley of Bílá Opava Brook, 1.8 km ENE of Ovčárna, 50°04'35"N, 17°15'53"E, 1170–1180 m, on bark of Picea abies, 2015, Malíček 8490, Kocourková, Vondrák & Zemanová, hb Malíček; ibid., Praděd National Nature Reserve, old-growth spruce forest c. 200 years old on E-facing slope of Mt Vysoká hole (1464 m), 0.2 km WNW of Eustaška hut, 50°03'35"N, 17°15'12"E, 1220 m, at base of Picea abies, 2015, Malíček 8563, Kocourková, Palice & Vondrák, hb Malíček. Frýdek-Místek, Beskydy Protected Landscape Area, Ostravice, Mazák National Nature Reserve, old-growth spruce forest with intermixed sycamores on W-facing slope of Mt Lysá hora (1323 m), 49°32'41"N, 18°26'43"E, 1200 m, on bark of Picea abies, 2016, Malíček 9743 & Palice, hb Malíček.

Finland, Pohjois-Karjala, Lieksa, Koli National Park (plot 9), East side, old-growth forest, on bark of fallen Picea abies (decay stage 3), 63.1033°N, 29.8140°E, 2013, Kantelinen 1865 (DNA A575, apothecia and pycnidia), H. Ibid., on wood of fallen Picea abies (decay stage 4), 2013, Kantelinen 1909 (DNA A583), H. Ibid., on wood of dead standing Picea abies (decay stage 3), Kantelinen 1685 (DNA A574), H. Ibid., on wood of fallen Picea abies (decay stage 5), 2013, Kantelinen 2003 (DNA A594), H. Ibid., on wood of fallen Picea abies (decay stage 3), 2013, Kantelinen 1923 (DNA A573), H. Etelä-Häme, Hämeenlinna, Evo (plot 8), protected old managed forest, on wood/mosses of a Picea abies stump (decay stage 5), 61.2088°N, 25.1363°E, 2013, Kantelinen 2899 (DNA A736). Ibid., on wood of Picea abies, 2013, Kantelinen 1686 (DNA A768), H. Ibid., Rajakallio, boreal forest on a bouldery slope, forest of Picea, Pinus and Betula, 61°15.27'N, 025°06.43'E, on bark of rotten wood among boulders, 2007, Palice 11684, conf. Coppins, H. Uusimaa, Tuusula, west of Korso, shaded and dense Picea abies dominated managed forest (plot 2), on wood of a Picea abies stump (decay stage 5), 60.3544°N, 25.0322°E, 2013, Kantelinen 2643 (DNA A484), H.

Sweden, Jämtland, Kall par., about 850 m NW of the northwestern tip of Lake Spjuttjärnen, S side of stream Konäsån, on stump of Betula pubescens in old-growth Picea abies forest, 63°34'30"N, 13°04'05"E, elev. 440 m, 2022, Svensson 4335, UPS L-1091180.

Ukraine. Eastern Carpathians, Nadvirna, Bysrytsia, N of hill Skali verkhni, 48°27'48.492"N, 24°18'35.46"E, 1233 m, on bark of Picea abies, 2019, Vondrák 22217, PRA.