Species characterised by pale, usually endolithic thallus, perithecia leaving shallow to deep pits in the rock, very variable involucrellum appressed to the exciple and ascospores (21–)24–28(–30) × (9–)10–12(–13) mm, morphologically rather similar to the other Finnish species of the V. subtilis complex, but the ITS sequence divergence between the species is 1.7–3.9%.

Finland. Varsinais-Suomi, Länsi-Turunmaa (Parainen), Ersby, 150 m SE of Stormossen, abandoned lime quarry, quarry waste hill, S-slope, on pebbles, 27 m alt., 60°17'N, 22°15'E, 3 Sept 2009 J. Pykälä 36722 (H9205739, GenBank accession number: MT229720).

Prothallus absent. Thallus white, grey or pale greyish-brown, endolithic or thinly epilithic, continuous or small patches surrounding perithecia, ca. 20–60 mm thick, algal cells (4–)5–8 mm. Perithecia 0.13–0.26 mm in diam., (1/2–)3/4(–1)–immersed, leaving shallow to deep pits in the rock, sometimes thinly thalline covered; 80–140 perithecia/cm². Ostiole inconspicuous, tiny, pale or dark, plane or depressed, ca. 20–30 mm wide. Involucrellum absent, apical, to the exciple base level or enveloping the exciple, 20–60 mm thick, appressed to the exciple. Exciple 0.18–0.27 mm in diam., wall dark brown or black, ca. 20–30 mm thick. Periphysoids ca. 25–35 × 1.5–2.5 mm. Asci 60–104 × 22–33 mm, 8-spored. Ascospores 0-septate, (20.6–)23.8–25.8–27.8(–30.3) × (8.7–)10.0–11.0–12.0(–12.9) mm (n = 117), perispore 1–1.5 mm thick.

All finds are from lime quarries or road cuttings of calcareous rocks. The species seems to prefer pebbles and stones in lime quarries. It occurs both in sun-exposed and rather shady habitats. The specimens are from SW and SE Finland. This suggests that V. bifurcata has a southern distribution in Finland.

The epithet refers to the dualistic nature of the involucrellum of the species: absent or short vs. long or enveloping the exciple.

Finland. Varsinais-Suomi, Särkisalo, Förby, E of Vähämaankaula, abandoned lime quarry, beneath NW-facing wall, on stone, 7 m alt., 60°05'N, 22°52'E, 23 July 2008, J. Pykälä 33120 (H); Länsi-Turunmaa (Parainen), Simonby, Gropen, abandoned lime quarry, road cutting of calciferous rock, on pebbles, 15 m alt., 60°16'N, 22°13'E, 16 Sept 2009, J. Pykälä 37228 (H); Etelä-Savo, Kerimäki, Ruokojärvi, Pitkäniemi, abandoned lime quarry, on NE-facing wall, 90 m alt., 61°56'N, 29°00'E, 15 Sept 2011, J. Pykälä 45762 (H).

Verrucaria bifurcata is a somewhat puzzling species as it has a very variable involucrellum. Two specimens are characterised by an absent or small involucrellum and two by a deep reaching involucrellum. In the former case, the involucrellum varies within a specimen from absent to apical. In the latter case, the involucrellum extends to the exciple base level or envelopes the exciple. Verrucaria bifurcata cannot be identified with certainty without ITS sequencing. Nevertheless, it shows morphological variation differing from the other species in the V. subtilis complex. Verrucaria bifurcata is the only species in the V. subtilis complex in which involucrellum may be absent or enveloping the exciple. In V. bifurcata, the involucrellum is always tightly appressed to the exciple and sometimes it is difficult to find out whether the involucrellum is absent or enveloping the exciple. The specimen 45762 was originally identified as V. adelminienii Zschacke (Pykälä 2013). However, the type of V. adelminienii is not identifiable (Pykälä 2016). Furthermore, the spore size in the original description (Zschacke 1933) is smaller than the spore size in the Finnish specimen.

Species morphologically somewhat similar to V. subtilis, ascospores slightly larger: (23–)25–30(–34) × (10–)11–13(–14) mm and the ITS sequence divergence between the species is 2.8–3.4%.

Finland. Koillismaa, Kuusamo, Oulanka National Park, Mataraniemi, shore of Oulankajoki river, treeless stony river shore, on dolomite stones, 145 m alt., 66°22'N, 29°20'E, 26 Aug 2011, J. Pykälä 45168 (H9205102, GenBank accession number: MT229725).

Prothallus absent. Thallus grey to pale greyish-brown, endolithic or thinly epilithic, continuous, 20–80 mm thick, algal cells 5–8 mm. Perithecia 0.15–0.28 mm in diam., 1/2–1-immersed, leaving shallow to deep pits in the rock, often surrounded by thallus collar, few perithecia thinly thalline covered; 80–160 perithecia/ cm². Ostiole inconspicuous, dark, plane or depressed. Involucrellum apical to covering half of the exciple, in one specimen also few longer involucrella almost reaching the exciple base level present, 30–60 mm thick, appressed to the exciple or slightly diverging from the exciple. Exciple 0.16–0.32 mm, wall dark brown or black, ca. 15–25 mm thick. Periphysoids (25–)30–40(–50) × 1.5–2.5 mm, branching. Asci 8-spored. Ascospores 0-septate, two 1-septate spores seen in one specimen, (23.1–)25.1–27.5–29.8(–34.1) × (9.8–)10.7–11.6–12.6(–13.7) mm (n = 111), perispore 1 mm thick.

Two specimens of the species are from SW Finland and one specimen from NE Finland. The three sequenced specimens are from different kinds of habitats: dolomite stone on river shore (apparently periodically submerged), calcareous rock on seashore (perhaps not submerged) and in a lime quarry on pebbles. The species may prefer more humid (but preferably sun-exposed?) habitats than the other species in the V. subtilis complex.

The perithecia of the species leave shallow to deep pits in the rock when decayed.

Finland. Varsinais-Suomi, Raasepori (Karjaa), Knapsby, Mustio lime quarry, deciduous forest on lime quarry waste, on pebbles, 45 m alt., 60°10'N, 23°49'E, 2 July 2009, J. Pykälä 34527 (H); Länsi-Turunmaa (Iniö), Söderby, Biskopsö island, calcareous rock outcrop on shore of the Baltic Sea, on N-slope, scarce, 7 m alt., 60°20'N, 21°28'E, 9 June 2010, J. Pykälä 37975 (H).

The species cannot be morphologically separated with certainty from the other species of the V. subtilis complex. It is most difficult to separate from V. subtilis. On average, V. cavernarum has slightly longer (mean 2.3 mm longer than in V. subtilis) and broader (mean 1.1 mm broader than in V. subtilis) spores and pale exciples have not been found.

[Russia,] Suojärvi, ad saxa calcarea Pöpönsaari, 1870, Norrlin (H!, H-NYL 3036a!, syntypes).

Prothallus absent. Thallus white, grey or pale brown, endolithic, rarely epilithic (two sequenced specimens), thin, continuous, algal cells 5–8 mm, occasionally (three sequenced specimens) contiguous conspecific thalli separated by dark brown lines, 0.13–0.22 mm wide. Perithecia 0.13–0.40 mm in diam., (1/4–)1/2–1-immersed, leaving shallow to deep pits in the rock, few perithecia occasionally not leaving pits, often surrounded by a thalline collar, sometimes thinly thalline covered; 50–140 perithecia/cm². Ostiole usually inconspicuous, pale or dark, plane or depressed, ca. 20–50 mm wide. Involucrellum absent or apical, short, rarely covering half of the exciple (two sequenced specimens), (40–)50–80 mm thick, appressed to the exciple or diverging from the exciple. Exciple 0.20–0.35 mm in diam., wall dark brown or black, ca. 27–40 mm thick, apex thickened to ca. 50–100 mm thick if the involucrellum is absent. Periphysoids ca. 30–50(–60) × 1–2.5 mm, branching or branched-anastomosing. Ascospores 0-septate, (20.2–)24.6–27.4–30.2(–34.8) × (10.2–)11.7–12.6–13.5(–15.7) mm (n = 281), perispore 1 mm thick.

The species is a strict calcicole occurring on calcareous rocks. It may prefer fairly humid habitats. Verrucaria devergens seems to be able to tolerate moderate flooding and it also grows on subaquatic calcareous rocks on river shores in the Oulanka area. It is not rare on dolomite rocks in the Oulanka and Kilpisjärvi areas in northern Finland, but seems to be absent from southern Finland.

Finland. Koillismaa, Kuusamo, Oulanka National Park, Pikkukönkäänkuru, Pinus sylvestris-dominated forest, SW-slope, on dolomite stones, 178 m alt., 66°21'N, 29°19'E, 8 Aug 2009, J. Pykälä 35922 (H); Kuusamo, Oulanka National Park, Pikkukönkäänkuru, dolomite rock crop, on overhanging SW-facing wall, 173 m alt., 66°21'N, 29°19'E, 8 Aug 2009, J. Pykälä 35933 (H); Kuusamo, Oulanka National Park, Pikkuköngäs, N shore of river Oulankajoki, dolomite rock outcrop, on SW-facing wall, 160 m alt., 66°22'N, 29°19'E, 12 Aug 2009, J. Pykälä 36220 (H), 36244 (H), 36245 (H); Kuusamo, Oulanka National Park, Pikkuköngäs, N shore of river Oulankajoki, dolomite rock outcrop, stony shore, on stones, 160 m alt., 66°22'N, 29°19'E, 12 Aug 2009, J. Pykälä 36234 (H); Kuusamo, Oulanka National Park, Pikkuköngäs, N shore of river Oulankajoki, dolomite rock outcrop, on 1 m high SW-facing wall, 160 m alt. 66°22'N, 29°19'E, 12.VIII.2009, J. Pykälä 36271 (H); Kuusamo, Oulanka National Park, Kiutaköngäs, N shore of river Oulankajoki, dolomite rock outcrop, on SE-slope, 150 m alt., 66°22'N, 29°20'E, 12 Aug 2009, J. Pykälä 36304 (H); Kuusamo, Oulanka National Park, Kiutaköngäs, by the rapids, S shore of Oulankajoki river, calciferous (dolomite) schistose rock outcrop, NE-slope, on E-facing wall, 152 m alt., 66°22'N, 29°19'E, 13 Aug 2010, J. Pykälä 39898 (H); Kuusamo, Oulanka National Park, Kiutaköngäs, by the rapids, S shore of Oulankajoki river, calciferous (dolomite) schistose rock outcrop, on gentle NE-slope, 152 m alt., 66°22'N, 29°19'E, 13 Aug 2010, J. Pykälä 39901 (H); Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, stony river shore, on dolomite stone, 170 m alt., 66°24'N, 29°11'E, 25 Aug 2011, J. Pykälä 45090 (H); Kuusamo, Oulanka National Park, Mataraniemi W, shore of Oulankajoki river, small dolomite rock outcrop, on 40 cm high SE-facing wall, 145 m alt., 66°22'N, 29°20'E, 28 Aug 2011, J. Pykälä 45367 (H); Salla, Oulanka National Park, 400 m N of Savilampi, shore of river Savinajoki, cliff, dolomite rock outcrop, on overhanging NE-facing wall, 177 m alt. 66°25'N, 29°10'E, 13 Aug 2009, J. Pykälä 36344 (H); Salla, Oulanka National Park, Savilampi 1.4 km NE, shore of Savinajoki river, dolomite rock outcrop, SE-slope, on dolomite boulder, 184 m alt., 66°26'N, 29°11'E, 23 Aug 2011, J. Pykälä 44914 (H); Enontekiön Lappi, Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, gentle SW-slope, dolomite scree, on dolomite boulders , 710 m alt., 69°11'N, 21°26'E, 3 Aug 2011, J. Pykälä 43421 (H); Enontekiö, Kilpisjärvi, Saana, nature reserve, E-part, fell, dolomite rock outcrop, on SW-facing wall, 880 m alt., 69°02'N, 20°50'E, 10 Aug 2011, J. Pykälä 44042 (H).

Based on the ITS phylogeny, V. devergens, V. karelica and V. subdevergens are very closely related. They are here considered as distinct species, based on the ITS phylogeny and because of a barcoding gap between the species. Verrucaria devergens is morphologically more variable than previously known (Pykälä 2007). Usually, the species has no involucrellum, but the apex of the exciple is thickened. However, specimens with an apical involucrellum, as well as two specimens in which the involucrellum covers half of the exciple, have an identical ITS sequence compared to the typical V. devergens. Typically, V. devergens has perithecia varying from half-immersed to immersed in the same specimen, but in some specimens, the perithecia are 3/4–1-immersed, while in a few others, they are 1/4–1/2-immersed.

Verrucaria devergens is difficult to separate from V. foveolata, V. karelica and V. subdevergens. V. devergens and V. foveolata show similar variation in the involucrellum, i.e. absent or apical. Verrucaria foveolata has larger spores, but there is a wide overlap in the spore size. Verrucaria foveolata usually has immersed perithecia, while V. devergens has 1/2–1-immersed perithecia. However, some specimens of V. devergens are similar to V. foveolata in having 3/4–1-immersed perithecia. No consistent morphological differences were found between V. devergens and V. karelica, although all specimens of V. karelica have an involucrellum. Verrucaria karelica may have more often an epilithic thallus and dark lines between contiguous conspecific thalli. Verrucaria subdevergens has a longer involucrellum than V. devergens in all studied specimens predominantly exceeding half of the exciple.

Specimens of V. devergens with untypically deep reaching involucrellum may be difficult to separate from V. kuusamoensis and V. subtilis. Verrucaria kuusamoensis tend to have a smaller exciple and shorter periphysoids, the thallus is usually epilithic and the involucrellum usually exceeds half of the exciple. Verrucaria subtilis has thinner and smaller exciple and, on average, smaller spores. In some specimens of V. subtilis, pale exciples are present, while they have never been found from V. devergens.

Species characterised by perithecia 1/4–3/4-immersed, leaving usually shallow pits, involucrellum covering half of the exciple or almost to the exciple base, ascospores (23–)25–29(–34) × (10–)11–12(–13) mm, morphologically rather similar to the other Finnish species of the V. subtilis complex, but the sequence divergence in ITS 1.7–2.6%.

Finland, Varsinais-Suomi, Karkkila, Haavisto, 100 m S of E-part of Iitalammi, S-slope, clear cut herb-rich forest, on calcareous stone, 60°31'N, 24°23'E, 123 m alt., 7 June 2008 J. Pykälä 32687 (H9205096, GenBank accession number: MT229742).

Prothallus absent. Thallus white or grey, inconspicuous, endolithic to thinly epilithic, continuous to irregularly rimose, ca. 20–80 mm thick, algal cells 5–7(–8) mm. Perithecia 0.18–0.36 mm in diam., 1/4–3/4(–1)–immersed, leaving shallow to more rarely deep pits in the rock, often thinly thalline covered except apex; 60–160 perithecia/cm². Ostiole inconspicuous, tiny, pale to usually dark, plane or depressed, ca. 20–30 mm wide. Involucrellum covering half of the exciple or almost to the exciple base, 40–70 mm thick, appressed to the exciple or slightly or moderately diverging from it. Exciple 0.16–0.28 mm in diam., wall dark brown, ca. 20–25 mm thick. Periphysoids (20–)25–35(–40) × 1.5–2.5 mm, some branching. Asci 77–101 × 23–28 mm, 8-spored. Ascospores (22.7–)25.1–27.0–28.9(–33.6) × (9.6–)10.6–11.4–12.3(–13.3) (n = 78), perispore 1 mm thick.

Four sequenced specimens occur: two from SW Finland and two from NE Finland. The species grows on calcareous rocks and in lime quarries, on walls, boulders, stones and pebbles. Verrucaria difficilis may prefer half-shady habitats. The species is rare, but may also have been overlooked due to its morphological similarity to several other species.

The species may be mixed up with several other species of Verrucaria.

Finland, Koillismaa, Kuusamo, Oulanka National Park, Kiutaköngäs 400 m N, Pinus sylvestris-dominated forest, small dolomite rock outcrop, SW-slope, on pebbles, 165 m alt., 66°22'N, 29°19'E, 2 Aug 2010, J. Pykälä 39060 (H); Kuusamo, Juuma, Niskakoski, calciferous (dolomite) schistose rock outcrop, on calciferous boulder, 225 m alt., 66°13'N, 29°24'E, 22 Aug 2011, J. Pykälä 44811 (H); Uusimaa, Vantaa, Sotunki, Bisa, 300 m E-NE, herb-rich forest, abandoned lime quarry, on SW-facing wall, 35 m alt., 60°17'N, 25°08'E, 7 June 2011, J. Pykälä 41859 (H).

Based on the ITS phylogeny, V. difficilis belongs to the V. subtilis complex with V. bifurcata, V. cavernarum and V. subtilis. The involucrellum is usually longer than in V. cavernarum and V. subtilis. Furthermore, the perithecia of V. difficilis are, on average, less immersed, often only 1/4–1/2-immersed in rock. Verrucaria bifurcata differs in more immersed perithecia with the involucrellum appressed to the exciple. Nevertheless, V. difficilis may not be identified with certainty without sequencing. Verrucaria difficilis is also difficult to separate from V. kuusamoensis. This species has slightly longer spores and the perithecia commonly leave deep pits in the rock.

A Genbank sequence Verrucaria calkinsiana Servít (KT695332) has 98% similarity to V. difficilis and it remains to be studied whether it is a closely-related species or possibly conspecific. Based on the morphology of the type specimen (PRM-857016!), V. calkinsiana does not belong to the V. subtilis complex and the sequenced specimen is apparently misidentified.

Not seen. Protologue: “auf Kalksteinen bei Rüdersdorf”.

Prothallus absent. Thallus white, grey or pale brown, endolithic, often inconspicuous, rarely thinly epilithic, algal cells 5–9 mm. Perithecia 0.11–0.42 mm, (1/2–)3/4–1-immersed in rock, leaving deep pits in the rock, commonly surrounded by a thallus collar, sometimes covered by a thin thalline layer except for the apex; (30–)60–120 perithecia/cm². Ostiole usually inconspicuous, tiny, pale or dark, plane or depressed, ca. 20–40(–50) mm wide, wider ostiolar depression rarely present up to 80 mm wide. Involucrellum absent or apical, rarely covering half of the exciple, 40–60 mm thick. Exciple 0.19–0.42 mm in diam., usually round, but sometimes pear-shaped or at least longer than broad, medium brown (rarely), dark brown or black, ca. (20–)25–43(–60) mm thick, apex sometimes thickened to ca. 40–60 mm thick if the involucrellum is absent. Periphysoids ca. (30–)40–65 × 1–2(–3) mm, branching. Asci 78–102 × 27–39 mm, 8-spored. Ascospores 0-septate, rarely solitary spores 1-septate, (23.6–)27.4–30.5–33.7(–37.3) × (10.4–)12.1–13.4–14.6(–17.1) mm (n = 197), perispore 1–1.5 mm thick.

The species grows on calcareous rocks and in lime quarries, both on sun-exposed and shady rocks, both in southern and in northern Finland.

Finland. Varsinais-Suomi, Lohja, Torhola, 400 m E of Torhola cave, S-slope, calcareous rock outcrop, 40 m alt., 60°15'N, 23°52'E, 20 July 2007, J. Pykälä 31528 (H); Salo (Kisko), Leilä, Kalkuuni, Pinus sylvestris-dominated forest, SW-slope, on calcareous rock wall, 60 m alt., 60°12'N, 23°35'E, 14 July 2009, J. Pykälä 34953 (H); Länsi-Turunmaa (Korppoo), Åfvensår, Kilamo, abandoned lime quarry, on SW-facing wall, 13 m alt., 60°17'N, 21°32'E, 28 July 2009, J. Pykälä 35395 (H); Salo (Kisko), Haapaniemi, Plantmaannokka, calcareous rock outcrop on shore of Lake Määrjärvi, on NE-facing wall, 42 m alt. , 60°12'N, 23°31'E, 4 June 2010, J. Pykälä 37728 (H); Salo (Kisko), Jyly, 200 m NE of Purslammi, calcareous rock outcrop, on NW-facing wall, 67 m alt., 60°14'N, 23°36'E, 17 June 2010, J. Pykälä 38119 (H); Kemiönsaari (Dragsfjärd), Olmos, Kolaskär island, calcareous rock outcrop on shore of the Baltic Sea, beneath SE-facing wall, on pebbles, 2 m alt., 60°03'N, 22°19'E, 12 July 2010, J. Pykälä 38719 (H); Koillismaa, Kuusamo, Oulanka, Putaanoja, 500 m W-NW of Hautala, Pinus sylvestris-dominated semi-open forest, dolomite rock outcrop, on N-slope, 230 m alt., 66°22'N, 29°25'E, 9 Aug 2009, J. Pykälä 35965 (H); Kuusamo, Kallunki, Merenvaara, Pinus sylvestris-dominated forest, NW-slope, small dolomite rock outcrop, on W-facing wall, 225 m alt., 66°20'N, 29°20'E, 2 Aug 2010, J. Pykälä 39028 (H); Kuusamo, Oulanka National Park, Kiutaköngäs 400 m N, SE-slope, Pinus sylvestris-dominated forest, small dolomite rock outcrop, on SW-facing wall, 170 m alt., 66°22'N, 29°19'E, 5 Aug 2010, J. Pykälä 39294 (H); Salla, Oulanka National Park, W of Savikoski, cliff, dolomite rock outcrop, NE-slope, on dolomite boulder, 185 m alt., 66°25'N, 29°10'E, 17 Aug 2010, J. Pykälä 40195 (H); Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, Picea abies-dominated herb-rich forest, dolomite rock outcrop, NE-slope, on dolomite boulder, 174 m alt., 66°24'N, 29°11'E, 20 Aug 2011, J. Pykälä 44553 (H); Salla, Hautajärvi, Kurtinniittykuru, dolomite rock outcrop, on flat surface, 195 m alt., 66°26'N, 29°09'E, 24 Aug 2011, J. Pykälä 44952 (H).

Fennoscandian specimens of Verrucaria with large spores, perithecia leaving deep pits in the rock and immersed in rock, lacking an involucrellum and with endolithic pale thallus have been predominantly treated as V. foveolata (e.g. Foucard 2001). It remains uncertain whether V. foveolata is the correct name for this common species, as the type material was not located. The absence of involucrellum has been used as the main character to separate V. foveolata from morphologically-similar species with apical involucrella, such as V. dolomitica (A. Massal.) Kremp. (Breuss 2004). However, the sequenced Finnish specimens with an apical involucrellum do not differ from specimens without an involucrellum.

Based on the ITS phylogeny, Verrucaria foveolata and V. subjunctiva are not monophyletic, but together form a strongly-supported group. However, the two taxa are, for the time being, treated as separate species pending further study. Most specimens can be identified by their morphology, although we found some intermediate specimens having morphological characters pointing to both species. However, overlap in the morphology is not larger than compared to several, not closely related species of Verrucaria. Verrucaria foveolata is more difficult to be separated from V. devergens (see the species) than from V. subjunctiva. Furthermore, some ecological and biogeographical differences seem to occur between V. foveolata and V. subjunctiva. Verrucaria subjunctiva has not been found from lime quarries, whereas several populations of V. foveolata occur in lime quarries. Verrucaria foveolata is fairly common on calcareous rocks both in southern and northern Finland, whereas V. subjunctiva is rare in southern Finland.

Species characterised by dark lines between contiguous conspecific thalli, pale endolithic thallus, small perithecia leaving shallow to deep pits in the rock, involucrellum reaching the exciple base level and appressed to the exciple, ascospores measuring (21–)24–28(–29) × (10–)11–12(–13) mm.

Finland. Koillismaa, Kuusamo, Oulanka National Park, Pikkuköngäs, N shore of river Oulankajoki, dolomite rock outcrop, on SW-facing wall, 160 m alt., 66°22'N, 29°19'E, 12 Aug 2009, J. Pykälä 36222 (H, GenBank accession number: MT229758).

Prothallus not seen. Thallus pale grey, endolithic, dark lines between contiguous conspecific thalli, 0.21–0.35 mm wide. Perithecia 0.11–0.26 mm in diam., (1/2–)3/4–immersed, leaving shallow to deep pits in the rock, surrounded by a thallus collar; 120–140 perithecia/cm². Ostiole inconspicuous, tiny, pale to dark, plane or depressed, ca. 30 mm wide. Involucrellum reaching the exciple base, 50–60 mm thick, appressed to the exciple. Exciple 0.18–0.25 mm in diam., wall dark brown to black. Periphysoids ca. 25–35 × 2–2.5 mm. Asci 8-spored. Ascospores 0-septate, (21.2–)24.5–26.5–28.4(–29.4) × (10.0–)10.9–11.7–12.5(–13.2) mm (n = 36), perispore 1 mm thick.

The only known specimen is from a dolomite rock on a river shore in north-eastern Finland, in Kuusamo.

The only specimen available is characterised by dark lines between contiguous conspecific thalli.

Verrucaria fuscozonata did not group with any of the examined species in the ITS phylogeny. However, it is morphologically rather similar to V. bifurcata, V. kuusamoensis and V. subdevergens. In V. bifurcata, dark lines between contiguous conspecific thalli are absent and the involucrellum usually thinner. In V. kuusamoensis and V. subdevergens, the spores are larger and the perithecia occur less densely. More material is needed to find out whether V. fuscozonata can be unambiguously identified, based on morphology only.

Russia, Karelia Onegensis, Mundjärvi, supra saxa dolomitica cinerea, J. P. Norrlin (H-NYL 3146!, H!, syntypes).

Prothallus absent. Thallus white, grey or pale greyish-brown, endolithic or thinly epilithic, farinose, algal cells 5–8 mm, contiguous conspecific thalli often separated by dark lines, 0.13–0.22 mm wide. Perithecia 0.07–0.37 mm, (1/2–)3/4–1-immersed, leaving shallow to usually deep pits in the rock, surrounded by a thalline collar; 40–80 perithecia/cm². Ostiole pale or dark, plane or depressed ca. 20–40(–60) mm wide. Involucrellum apical or covering half of the exciple, 50–70 mm thick, appressed to the exciple or diverging from the exciple. Exciple 0.21–0.28 mm in diam., wall dark brown to black, ca. 20–31 mm thick. Periphysoids ca. 30–50 × 2–2.5(–3) mm. Asci ca. 66–84 × 26–33 mm, 8-spored. Ascospores 0-septate, (23.2–)26.2–27.9–29.5(–31.3) × (10.3–)11.7–12.3–13.0(–14.1) mm (n = 63), perispore not seen, but may have vanished during storage.

This species is known from Finland only from the Oulanka area in the biogeographical province of Koillismaa in NE Finland where it grows on dolomite rocks. It seems to occur in fairly shady habitats.

Finland. Koillismaa, Salla, Oulanka National Park, Savikoski 300 m W, Pinus sylvestris-forest, steep N-slope, dolomite rock outcrop, on N-facing wall, 180 m alt., 66°25'N, 29°10'E, 10 Aug 2010, J. Pykälä 39625 (H); Kuusamo, Oulanka, Putaanoja, 500 m W-NW of Hautala, NE-slope, dolomite rock outcrop, on 50 cm high SW-facing wall, scarce, 232 m alt., 66°22'N, 29°25'E, 15 Aug 2010, J. Pykälä 39991 (H); Kuusamo, Oulanka National Park, Kiutaköngäs N, steep S-slope, Pinus sylvestris-dominated forest, dolomite rock outcrop, on SW-facing wall, 182 m alt., 66°22'N, 29°19'E, 19 Aug 2010, J. Pykälä 40325 (H); Salla, Oulanka National Park, W of Savikoski, cliff, dolomite rock outcrop, on NE-facing wall, scarce, 185 m alt., 66°25'N, 29°10'E, 17 Aug 2010, J. Pykälä 40235 (H).

The type specimens of V. karelica have epilithic thalli and contiguous conspecific thalli are separated by dark lines. None of the Finnish specimens has both epilithic thalli and dark lines. However, one of the sequenced specimens has epilithic thalli and another specimen has dark lines. Thus, based on morphology, this entity probably belongs to V. karelica. The type locality of V. karelica (Vainio 1921) is situated rather close to the Oulanka area, suggesting that the species would probably occur in the Oulanka area. The species is closely related to V. devergens and V. subdevergens. V. devergens and V. karelica may not be unambiguously separated by morphology only. Verrucaria devergens usually has endolithic thalli and several specimens lack an involucrellum. Verrucaria karelica may be absent from subaquatic habitats unlike V. devergens which often grows on river shores. Verrucaria subdevergens has an involucrellum usually exceeding half of the exciple height. The species is also difficult to be separated from several other species of Verrucaria belonging to the Thelidium group. Verrucaria cavernarum, V. difficilis and V. subtilis always lack dark lines between contiguous conspecific thalli and the spores are smaller. Verrucaria kuusamoensis usually has an involucrellum exceeding half of the exciple.

Species characterised by pale, usually thinly epilithic thallus, rather large perithecia leaving shallow to deep pits in the rock, involucrellum usually covering more than half of the exciple, ascospores (21–)26–30(–34) × (9–)11–13(–14) mm, morphologically difficult to separate from V. subdevergens, but the sequence divergence in ITS 6.8–7.4%.

Finland. Koillismaa, Kuusamo, Juuma, Oulanka National Park, Hautaniitynvuoma, gorge, dolomite rock outcrop, on high NE-facing wall, 190 m alt., 66°15'N, 29°26'E, 21 Aug 2011, J. Pykälä 44703 (H9205113 – holotype, UPS – isotype, GenBank accession number: MT229776).

Prothallus absent. Thallus white, grey or more rarely pale brown, endolithic or usually thinly epilithic, continuous or rimose, often farinose, up to 0.2 mm thick, algal cells (4–)5–7 mm, contiguous conspecific thalli sometimes separated by a dark line, 0.12–0.35 mm wide, present in only few specimens. Perithecia 0.17–0.45 mm in diam., (1/4–)1/2–3/4(–1)-immersed, leaving shallow to deep pits in the rock, rarely few perithecia not leaving pits, often thinly thalline covered except apex; (30–)40–120 perithecia/cm². Ostiole tiny, pale or dark, plane or depressed, ca. 20–40(–60) mm wide, occasionally wider ostiolar depression up to 110 mm wide. Involucrellum covering half of the exciple or to the exciple base level, rarely in few perithecia enveloping the exciple, (30–)40–70(–80) mm thick, appressed to the exciple or slightly or moderately diverging from it. Exciple 0.19–0.29 mm in diam., wall dark brown or black, rarely pale, ca. 20–42 mm thick. Periphysoids ca. (20–)25–40 × (1.5–)2–2.5(–3) mm. Asci 68–102 × 25–34 mm, 8-spored. Ascospores 0-septate, (21.4–)25.5–27.9–30.3(–34.5) × (9.3–)11.3–12.2–13.1(–14.2) mm (n = 312), perispore 1 mm thick.

Verrucaria kuusamoensis is rather common on dolomite rocks in the Oulanka area in the municipalities of Kuusamo and Salla in the biogeographical Province of Koillismaa (Ks). It seems not to occur in southern Finland.

Most specimens of the species originate from the Kuusamo area.

Finland. Koillismaa, Kuusamo, Paljakka, E shore of Kuusinkijoki river, Kiukaankorva, dolomite rock outcrop, on overhanging NW-facing wall, scarce, 213 m alt., 66°11'N, 29°38'E, 5 Aug 2009, J. Pykälä 35710 (H); Kuusamo, Oulanka National Park, Pikkukönkäänkuru, herb-rich heath forest, small dolomite rock outcrop, on W-facing wall, 165 m alt., 66°21'N, 29°19'E, 6 Aug 2009, J. Pykälä 35857 (H); Kuusamo, Oulanka National Park, Pikkukönkäänkuru, dolomite rock outcrop, on SW-facing wall, 175 m alt., 66°21'N, 29°19'E, 8 Aug 2009, J. Pykälä 35920 (H); Kuusamo, Oulanka National Park, Pikkuköngäs, N shore of river Oulankajoki, dolomite rock outcrop, on SW-facing wall, 160 m alt., 66°22'N, 29°19'E, 12 Aug 2009, J. Pykälä 36254 (H); Kuusamo, Oulanka National Park, Kiutaköngäs, Pinus sylvestris-dominated forest, steep SE-slope, dolomite rock outcrop, on SE-facing wall, rather scarce, 175 m alt., 66°22'N, 29°19'E, 12 Aug 2009, J. Pykälä 36294 (H); Salla, Oulanka National Park, 400 m N of Savilampi, shore of river Savinajoki, dolomite rock outcrop, on NE-slope, scarce, 178 m alt., 66°25'N, 29°10'E, 13 Aug 2009, J. Pykälä 36335 (H); Kuusamo, Oulanka National Park, Kiutaköngäs 400 m N, Pinus sylvestris-dominated forest, small dolomite rock outcrop, on SW-slope, 165 m alt., 66°22'N, 29°19'E, 2 Aug 2010, J. Pykälä 39052 (H); Kuusamo, Oulanka National Park, Kiutaköngäs, by the rapids, S shore of Oulankajoki river, calciferous (dolomite) schistose rock outcrop, NE-slope, on E-facing wall, rather scarce, 152 m alt., 66°22'N, 29°20'E, 13 Aug 2010, J. Pykälä 39900 (H); Salla, Oulanka National Park, W of Savikoski, cliff, dolomite rock outcrop, on NW-facing wall, very scarce, 185 m alt., 66°25'N, 29°10'E, 17 Aug 2010, J. Pykälä 40219 (H); Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, Picea abies-dominated herb-rich forest, dolomite rock outcrop, on NE-facing wall, 175 m alt., 66°24'N, 29°11'E, 20 Aug 2011, J. Pykälä 44563 (H); Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, Picea abies-dominated herb-rich forest, dolomite rock outcrop, on E-facing wall, 175 m alt., 66°24'N, 29°11'E, 20 Aug 2011, J. Pykälä 44570 (H); Kuusamo, Juuma, Oulanka National Park, Hautaniitynvuoma, gorge, dolomite rock outcrop, on high NE-facing wall, 190 m alt., 66°15'N, 29°26'E, 21 Aug 2011, J. Pykälä 44694 (H), 44696 (H); Kuusamo, Juuma, Oulanka National Park, Hautaniitynvuoma, gorge, stony NW-slope with sparse stunted birches, close to bottom, on dolomite stone, 182 m alt., 66°15'N, 29°26'E, 21 Aug 2011, J. Pykälä 44744 (H); Salla, Hautajärvi, Kurtinniittykuru, cliff, dolomite rock outcrop, on SE-facing wall, scarce, 195 m alt., 66°26'N, 29°09'E, 24 Aug 2011, J. Pykälä 44980 (H); Kuusamo, Oulanka National Park, Halosenkuru gorge, NW-slope, Picea abies-dominated forest, dolomite rock outcrop, on NW-facing wall, 215 m alt., 66°21'N, 29°26'E, 27 Aug 2011, J. Pykälä 45231 (H); Kuusamo, Oulanka National Park, Halosenkuru, gorge, dolomite rock outcrop, on SE-facing wall, scarce, 235 m alt., 66°21'N, 29°26'E, 28 Aug 2011, J. Pykälä 45330 (H).

The exciple wall of V. kuusamoensis is usually dark brown or black. However, one specimen with a pale exciple wall and one specimen with both pale and dark exciple walls have similar ITS sequences compared to the specimens with dark exciple walls. This species was erroneously reported as V. subjunctiva by Pykälä (2010a), while V. subjunctiva has larger spores and longer periphysoids. Verrucaria devergens has a shorter involucrellum. Verrucaria kuusamoensis may be most difficult to separate from V. subdevergens and V. difficilis. These species show wide overlap in their morphology. Verrucaria subdevergens more often has pale brownish thallus and slightly longer periphysoids. Verrucaria difficilis has, on average, less-developed thallus and the perithecia and the spores slightly smaller.

Differing from V. devergens by longer involucrellum, morphologically difficult to separate from V. kuusamoensis, but the sequence divergence in ITS 5.4–6.0%.

Finland, Koillismaa, Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, dolomite rock outcrop, on gentle NE-slope, 165 m alt., 66°24'N, 29°11'E, 25 Aug 2011, J. Pykälä 45109 (holotype: H9205097, GenBank accession number: MT229783).

Prothallus absent. Thallus white, grey, ochraceous or pale greyish-brown, endolithic to thinly epilithic, continuous to irregularly rimose, in one specimen contiguous conspecific thalli separated by a dark line. Perithecia 0.21–0.42 mm, 1/2–3/4-immersed, leaving shallow to deep pits in the rock, often surrounded by a thallus collar, in one specimen, thalline covered except apex, thalline cover 8–20 mm thick; 80–120 perithecia/cm². Ostiole inconspicuous, tiny, pale to dark, plane or depressed, ca. 20–40 mm wide. Involucrellum covering half of the exciple or to the exciple base, in few perithecia may envelope the exciple, 30–80 mm thick, in one specimen, often apically thickened to 50–70 mm thick, appressed to the exciple. Exciple 0.21–0.34 mm in diam., wall blackish-brown, ca. 15–25 mm thick. Periphysoids ca. 25–50 × 1.5–2 mm. Asci 82–94 × 27–33 mm, 8-spored. Ascospores 0-septate, (23.0–)25.4–28.2–31.0(–34.9) × (11.2–)12.0–13.0–13.9(–15.2) mm (n = 83), perispore 1–1.5 mm thick.

All three finds are from the Oulanka area in NE Finland where the species grows on dolomite rock outcrops and on a dolomite boulder.

The species is close to V. devergens.

Finland. Koillismaa, Kuusamo, Oulanka National Park, Kiutaköngäs 400 m N, Pinus sylvestris-herb-rich forest, small dolomite rock outcrop, on small S-facing wall, 165 m alt., 66°22'N, 29°19'E, 3 Aug 2010, J. Pykälä 39128 (H); Kuusamo, Oulanka National Park, Taivalköngäs, shore of Oulankajoki river, Picea abies-dominated herb-rich forest, dolomite rock outcrop, NE-slope, on dolomite boulder, 174 m alt., 66°24'N, 29°11'E, 20 Aug 2011, J. Pykälä 44550 (H).

This species is close to V. devergens and V. karelica, based on the ITS phylogeny. It differs from these species in a longer involucrellum mainly exceeding half of the exciple. Morphologically, V. subdevergens is most difficult to separate from V. kuusamoensis, which tends to have shorter periphysoids and the thallus is more often white.

[Russia,] Sibiria Septentrionalis: Si nus Konyam ad fretum Bering, 64°50' lat. bor., 173° long. occid. (Greenw.) 28–30.7.1879 E. Almquist (S-L46!, lectotype, designated here); Fretum Behring, Kongar Bay, E. Almquist (H-NYL 3512!, isolectotype).

Prothallus absent. Thallus white or grey, rarely pale ochraceous, endolithic or thinly epilithic, continuous or rimose, up to 0.1 mm thick, algal cells 5–8 mm. Perithecia (0.16–)0.23–0.45 mm in diam., (1/4–)1/2–3/4(–1)-immersed, not leaving pits or usually leaving shallow or deep pits in the rock, sometimes covered by a thin thalline layer except for the apex, often surrounded by a thalline collar; ca. (10–)30–100(–120) perithecia/cm². Ostiole tiny, pale or dark, plane or depressed, ca. 20–40(–50) mm wide, ostiolar depression rarely wide, up to 130 mm wide. Involucrellum exceeding half of the exciple or reaching the exciple base level, rarely enveloping the exciple, (40–)50–100 mm thick, appressed to the exciple or slightly to moderately diverging from the exciple. Exciple 0.20–0.36 mm in diam., wall dark brown or black, ca. 22–45 mm thick. Periphysoids ca. 30–60 × (1–)1.5–2.5 mm, branching. Asci 84–109 × 32–40 mm, 8-spored. Ascospores 0-septate, rarely very few spores 1-septate, (23.4–)27.0–30.4–33.8(–40.1) × (11.7–)12.6–13.8–15.0(–17.4) mm (n = 242), perispore 1–2 mm thick.

The species occurs on calcareous rocks in both sun-exposed and shady sites. Most sequenced specimens are from the biogeographical province of Koillismaa. Three sequenced specimens (two localities) originate from eastern Finland (biogeographical Province of Pohjois-Karjala) and three (two localities) from southern Finland (biogeographical Province of Varsinais-Suomi). In southern Finland, the species seems to be very rare. Verrucaria subjunctiva has not been collected in Finland from lime quarries.

Finland. Varsinais-Suomi, Länsi-Turunmaa (Korppoo), Åfvensår, Kilamo, calcareous rock outcrop, on flat rock, scarce, 17 m. alt., 60°17'N, 21°32'E, 28 July 2009, J. Pykälä 35326 (H); Länsi-Turunmaa (Korppoo), Åfvensår, Kilamo, calcareous rock outcrop, on flat rock, on pebbles, 17 m alt., 60°17'N, 21°32'E, 28 July 2009, J. Pykälä 35361 (H); Salo (Kisko), Haapaniemi, Plantmaannokka, calcareous rock outcrop on shore of Lake Määrjärvi, on calcareous boulder, 43 m alt., 60°12'N, 23°31'E, 4 June 2010, J. Pykälä 37746 (H); Koillismaa, Kuusamo, Oulanka National Park, Pikkukönkäänkuru, dolomite rock outcrop, on SW-facing wall, 173 m alt., 66°21'N, 29°19'E, 8 Aug 2009, J. Pykälä 35930 (H); Kuusamo, Oulanka National Park, Kiutaköngäs, N-shore of river Oulankajoki, dolomite rock outcrop, on SE-slope, 150 m alt., 66°22'N, 29°20'E, 12 Aug 2009, J. Pykälä 36308 (H); Salla, Oulanka National Park, 400 m N of Savilampi, shore of river Savinajoki, cliff, dolomite rock outcrop, on NW-facing wall, 177 m alt., 66°25'N, 29°10'E, 13 Aug 2009, J. Pykälä 36371 (H); Kuusamo, Juuma, Lammasvuoma, gorge, calciferous (dolomite) schistose rock outcrop, on NE-facing wall, 225 m alt., 66°16'N, 29°26'E, 8 Aug 2010, J. Pykälä 39475 (H), 39478 (H), 39491 (H); Salla, Oulanka National Park, Savilamminniemi, shore of lake Savilampi, cliff, dolomite rock outcrop, on E-facing wall, scarce, 185 m alt., 66°25'N, 29°10'E, 12 Aug 2010, J. Pykälä 39803 (H); Kuusamo, Oulanka National Park, Kiutaköngäs, by the rapids, shore of Oulankajoki river, calciferous (dolomite) schistose rock outcrop, N-slope, on boulder, 152 m alt., 66°22'N, 29°20'E, 18 Aug 2010, J. Pykälä 40284 (H); Kuusamo, Juuma, Oulanka National Park, Hautaniitynvuoma, gorge, dolomite rock outcrop, on high NE-facing wall, very scarce, 190 m alt., 66°15'N, 29°26'E, 21 Aug 2011, J. Pykälä 44671 (H); Kuusamo, Juuma, Oulanka National Park, Hautaniitynvuoma, gorge, stony NW-slope with sparse stunted birches, close to bottom, on dolomite boulder, 181 m alt., 66°15'N, 29°26'E, 21 Aug 2011, J. Pykälä 44734 (H); Salla, Oulanka National Park, Savilampi 1.2 km NE, steep E-slope, open area in forest, on small dolomite rock, 190 m alt., 66°26'N, 29°11'E, 23 Aug 2011, J. Pykälä 44881 (H); Pohjois-Karjala, Juuka, Polvela, Valkealampi, close by E-shore, Pinus sylvestris-dominated forest, calcareous rock outcrop, on W-slope, 176 m alt., 63°10'N, 29°07'E, 11 July 2011, J. Pykälä 42392 (H), 42419 (H); Juuka, Polvela, Valkealampi, close by E-shore, Pinus sylvestris-dominated forest, calcareous rock outcrop, W-slope, directly on rock, rather scarce, 175 m alt., 63°10'N, 29°07'E, 11 July 2011, J. Pykälä 42406 (H); Juuka, Petrovaara, Riihilahti S, shore of lake Polvijärvi, calcareous rock outcrop, on W-facing wall, 171 m alt., 63°09'N, 28°58'E, 13 July 2011, J. Pykälä 42510 (H).

This species has usually been treated as V. papillosa Ach. and was also reported from Finland as V. papillosa (Pykälä 2010a). However, Orange (2004b) showed that the type specimen of V. papillosa belongs to V. viridula (Schrad.) Ach. The type specimen of V. lacerata is small, but it fits rather well with the Finnish material. However, ITS sequences from Central Europe are needed to confirm the identity of V. lacerata. According to Breuss (2008b), the exciple size in V. lacerata is 0.4–0.6 mm, i.e. exceeding the size of V. subjunctiva. The ITS phylogeny does not separate V. subjunctiva from V. foveolata. These two taxa are here kept separated pending further study (see V. foveolata). Verrucaria subjunctiva and V. foveolata have larger spores than the other studied species. However, there is much overlap in the spore size of V. devergens and V. kuusamoensis and specimens with suboptimally-developed spores are easily misidentified. Verrucaria subjunctiva has larger perithecia and longer periphysoids than V. kuusamoensis.

[Switzerland] Bagnes-Thal, nördl. vom Hotel Monvoisin gegen den Plaine an Dolomitfelsen 16.9.1873 (G-00295028!, syntype); … Monvoisin & Bonat Mepa in Bagnes-Thal 1874 (G-00260361!, syntype?).

Prothallus absent. Thallus white, grey or pale brown, endolithic, or thinly epilithic, continuous to rimose, up to 0.1 mm thick. Perithecia 0.15–0.34(–0.44) mm in diam., (1/2–)3/4(–1)-immersed, leaving shallow to deep pits in the rock, few perithecia occasionally not leaving pits, sometimes covered by a thin thalline layer except for the ostiolar region; 40–160 perithecia/cm². Ostiole inconspicuous, tiny, pale or dark, plane or depressed, in two specimens, several ostioles slightly projecting, ca. 20–40(–70) mm wide. Involucrellum apical or covering half of the exciple, rarely in few perithecia exceeding half of the exciple, 30–70(–80) mm thick, appressed to the exciple to clearly diverging from the exciple. Exciple 0.16–0.33 mm in diam., wall pale or pale brown (rather rare), usually dark brown or black, 18–30 mm thick. Periphysoids ca. 20–40(–50) × (1–)1.5–2.5(–3) mm, branching. Asci 58–84 × 22–28 mm, 8-spored. Ascospores 0-septate, (19.8–)22.9–25.2–27.4(–30.7) × (8.3–)9.6–10.5–11.4(–12.8) mm (n = 400), perispore 1 mm thick.

The species grows on various calcareous rocks and in lime quarries. It occurs both in sun-exposed and shady habitats. It is amongst the most common species of Verrucaria on calcareous rocks of southern Finland. It may occur in the whole country, but the northernmost sequenced specimens are from the biogeographical province of Koillismaa. In Finland, V. subtilis is the most common species of Verrucaria belonging to the Thelidium group and having perithecia leaving pits in the rock.

Finland. Varsinais-Suomi, Lohja, Paavola, N of Rautaniemi, stony SE-slope, young Pinus sylvestris-plantation, on calcareous stone, 50 m alt., 60°13'N, 23°54'E, 21 May 2005, J. Pykälä 26865 (H); Pohja, Kuovila, 150 m NW of Valkjärvi, small rather flat calcareous rock outcrop, 50 m alt., 60°08'N, 23°23'E, 9 October 2006, J. Pykälä 29589 (H); Karkkila, Haavisto, 200 m N of Saaressuo, on calcareous rock outcrop, 132 m alt., 60°31'N, 24°22'E, 24 May 2008, J. Pykälä 32606 (H); Suomusjärvi, Sallittu, Huuttavanmäki, S-slope, on calciferous boulder, 110 m alt., 60°18'N, 23°37'E, 28 June 2008, J. Pykälä 32749 (H); Salo (Kiikala), Saari, Kalkkimäki, abandoned lime quarry, on NW-facing wall, 105 m alt., 60°25'N, 23°40'E, 4 July 2009, J. Pykälä 34601 (H); Salo (Kisko), Haapaniemi, Multsilta, calcareous rock outcrop, on shady N-facing wall, 65 m alt., 60°13'N, 23°29'E, 17 July 2009, J. Pykälä 35093 (H); Kemiönsaari (Västanfjärd), Billböle, Svinberget, calcareous rock outcrop, on W-slope, st pc, 25 m alt., 60°03'N, 22°43'E, 4 Sept 2009, J. Pykälä 36819 (H); Länsi-Turunmaa (Parainen), Hyvilemp, Hyvilemp, abandoned lime quarry, on SW-facing wall, scarce, 15 m alt., 60°17'N, 22°12'E, 14 Sept 2009, J. Pykälä 37102 (H); Karjalohja, Pyöli, E of Innoonlampi, rocky forest, on calcareous boulder, 46 m alt., 60°13'N, 23°49'E, 28 Sept 2009, J. Pykälä 37329 (H), 37331 (H); Salo (Kisko), Haapaniemi, Sorronniemi, abandoned lime quarry, on SE-facing wall, scarce, 65 m alt., 60°13'N, 23°30'E, 4 June 2010, J. Pykälä 37794 (H);

Salo (Kisko), Jyly, 200 m NE of Purslammi, calcareous rock outcrop, on NW-facing wall, 68 m alt., 60°14'N, 23°36'E, 17 June 2010, J. Pykälä 38140 (H); Salo (Särkisalo), Kaukosalo, Pyölinmäki, abandoned lime quarry, quarry spoil heap, NW-slope, on calcareous pebbles, 15 m alt., 60°07'N, 22°58'E, 17 June 2011, J. Pykälä 42225 (H); Koillismaa, Salla, Oulanka National Park, Pikkuköngäs, shore of river Oulankajoki, high cliff, dolomite rock outcrop, on SW-slope, 180 m alt., 66°25'N, 29°08'E, 13 Aug 2010, J. Pykälä 39870 (H); Kuusamo, Liikasenvaara, Iso Sirkkalampi 200 m E, SW-slope, young Larix-plantation, on dolomite boulder, rather scarce, 295 m alt., 66°21'N, 29°35'E, 18 Aug 2010, J. Pykälä 40280 (H); Salla, Oulanka National Park, Savilampi 850 m N, shore of Savinajoki river, river shore, on dolomite boulder, on S-facing wall, 182 m alt., 66°26'N, 29°10'E, 23 Aug 2011, J. Pykälä 44843 (H), 44844 (H); Keski-Pohjanmaa, Vimpeli, Vimpeli, Ryytimaa, lime quarry, quarry spoil heap, young deciduous forest, on calcareous boulders, rather scarce, 135 m alt., 63°09'N, 24°01'E, 31 Aug 2010, J. Pykälä 40596 (H);

Vimpeli, Vimpeli, Ryytimaa, lime quarry, S-slope, on pebbles, 125 m alt., 63°09'N, 24°01'E, 2 Sept 2010, J. Pykälä 40833 (H); Vimpeli, Möksy, Kotakangas, abandoned lime quarry, small quarry spoil heap, on pebbles, 122 m alt., 63°07'N, 23°58'E, 2 Sept 2010, J. Pykälä 40859 (H); Vimpeli, Möksy, Kotakangas, by abandoned lime quarry, quarry spoil heap, W-slope, on boulders, 120 m alt., 63°07'N, 23°58'E, 2 Sept 2010, J. Pykälä 40874 (H); Uusimaa, Vantaa, Sotunki, Bisa, 300 m E-NE, herb-rich forest, abandoned lime quarry, on SW-facing wall, 35 m alt., 60°17'N, 25°09'E, 7 June 2011, J. Pykälä 41857 (H); Pohjois-Karjala, Juuka, Nunnanlahti, Mustanvaara, dolomite rock outcrop, on SE-slope, 140 m alt., 63°09'N, 29°09'E, 14 July 2011, J. Pykälä 42540 (H); Etelä-Savo, Kerimäki, Ruokojärvi, Pitkäniemi, abandoned lime quarry, gravelly field, on calcareous pebbles, 85 m alt., 61°56'N, 29°00'E, 15 Sept 2011, J. Pykälä 45794 (H), 45817 (H), 45847 (H).

Verrucaria subtilis may be confused with several other species treated in this paper (see descriptions of these species). Verrucaria cavernarum and V. difficilis may differ by often longer involucrellum and slightly larger spores. The species may also be mixed up with Verrucaria epilithea Vain. and Verrucaria muralis Ach. These species have shorter spores (17–26 mm long) and the perithecia are not leaving pits in the rock or the pits are shallow. The first specimens of V. subtilis from Finland were identified as Verrucaria mimicrans Servít and V. transfugiens Zschacke (Pykälä and Breuss 2008). The type material of V. mimicrans has not been located and the identity of this species remains to be studied. Verrucaria transfugiens (see Pykälä 2016) differs in smaller spores and the presence of dark lines between contiguous conspecific thalli. Verrucaria hypophaea has usually been considered to belong to V. muralis or to V. schindleri Servít, which is said to differ from V. muralis by a dark exciple (Breuss 2007). However, V. hypophaea clearly differs from V. muralis by larger spores and the perithecia commonly leaving deep pits in the rock. The characters of V. hypophaea fit well with V. subtilis.

Species characterised by dark lines between contiguous conspecific thalli, pale usually endolithic thallus, perithecia leaving shallow to deep pits in the rock, very variable involucrellum, ascospores (18–)23–28(–32) × (8–)11–13(–15) mm, morphologically rather similar to the Finnish species of the V. subtilis complex, but the sequence divergence in ITS 4.5–6.8%.

Finland. Enontekiön Lappi, Enontekiö, Porojärvet, Toskalharji, Toskalpahta, fell, SW-slope, scree, on dolomite boulder, 795 m alt., 69°11'N, 21°29'E, 1 Aug 2011, J. Pykälä 43118 (H9205851, GenBank accession number: MT229829).

Prothallus absent. Thallus white, whitish grey or pale brownish, mainly endolithic to thinly epilithic, 20–170 mm thick, algal cells 5–10 mm, contiguous conspecific thalli separated by dark lines, 0.21–0.41 mm wide. Perithecia 0.15–0.47 mm in diam., 1/4–3/4-immersed, usually leaving shallow to fairly deep pits in the rock, rarely few perithecia not leaving pits, often surrounded by a thalline collar, 60–160(–200) perithecia/cm². Ostiole tiny or conspicuous, pale to dark, plane or depressed, ca. 20–40(–60) mm wide, wider ostiolar depression occasionally present, up to 160 mm wide. Involucrellum apical, covering half of the exciple, exceeding half of the exciple or rarely to the exciple base, 30–70(–90) mm thick, appressed to the exciple, moderately diverging from the exciple, strongly diverging from the exciple or even spreading outwards away from the exciple. Exciple 0.15–0.26 mm, wall dark brown or black, 17–35 mm thick. Periphysoids ca. 25–40(–50) × 1.5–2.5 mm, branching. Asci 67–84 × 27–28 mm, 8-spored. Ascospores 0-septate, (18.1–)22.7–25.3–28.0(–31.7) × (8.3–)10.8–11.9–13.1(–15.2) mm (n = 228), perispore 1–1.5 mm thick.

The species is restricted in Finland to the calcareous mountains (Scandes) in NW Finland above the tree level. It always grows on dolomite. It grows on rock outcrops, boulders, stones and pebbles.

The specific epithet refers to the high morphological variation in the involucrellum from apical to (rarely) reaching the exciple base level, from being appressed to the exciple to spreading outwards away from the exciple and from fairly thin to thick.

Finland. Enontekiön Lappi, Enontekiö, Porojärvet, Toskalharji, Toskalpahta, fell, SW-slope, scree, on dolomite pebbles, 785 m alt., 69°11'N, 21°29'E, 1 Aug 2011, J. Pykälä 43058 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, gentle SE-slope, dolomite rock outcrop, on dolomite stones, with V. foveolata, 730 m alt., 69°12'N, 21°26'E, 2 Aug 2011, J. Pykälä 43232 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, dolomite rock, gentle S-slope, on dolomite stone, 720 m alt., 69°12'N, 21°26'E, 2 Aug 2011, J. Pykälä 43272 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, dolomite rock, on SE-facing wall, 720 m alt., 69°12'N, 21°26'E, 2 Aug 2011, J. Pykälä 43296 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, dolomite rock, gentle SE-slope, on dolomite pebbles, 730 m alt., 69°12'N, 21°26'E, 2 Aug 2011, J. Pykälä 43302 (H); Enontekiö, Porojärvet, Toskalharji, Toskaljärvi N, fell, dolomite scree, on dolomite boulder, rather abundant, 710 m alt., 69°11'N, 21°26'E, 2 Aug 2011, J. Pykälä 43384 (H); Enontekiö, Kilpisjärvi, Saana, nature reserve, E-part, fell, dolomite rock, on SW-facing wall, 880 m alt., 69°02'N, 20°51'E, 10 Aug 2011, J. Pykälä 44075, 44081b (H); Enontekiö, Kilpisjärvi, Saana, fell, steep NE-slope, dolomite rock, on NE-facing wall, 820 m alt., 69°02'N, 20°51'E, 11 Aug 2011, J. Pykälä 44142, 44162 (H); Enontekiö, Kilpisjärvi, Saana, nature reserve, E-part, fell, steep SW-slope, dolomite rock, on SW-facing wall, 730 m alt., 69°02'N, 20°51'E, 12 Aug 2011, J. Pykälä 44255 (H).

Based on ITS sequences, V. vacillans is genetically well distinct from other Verrucaria species. However, it may be confused with several other species. Verrucaria vacillans is most difficult to separate from V. cavernarum, V. difficilis and V. subtilis. In these three species, dark lines between contiguous conspecific thalli are never present. Verrucaria cavernarum and V. subtilis have an involucrellum seldom exceeding half of the exciple (and then only in a minority of perithecia). The exciple of V. subtilis is sometimes pale (although usually dark). The spores tend to be slightly broader in V. vacillans than in V. subtilis. However, specimens of V. vacillans without dark lines and with a short involucrellum may not be possible to separate from V. cavernarum and V. subtilis by morphology. Specimens of V. vacillans with a deep reaching involucrellum may not be separable from V. difficilis if dark lines are absent. Verrucaria vacillans may also be confused with V. devergens, V. kuusamoensis, V. epilithea and V. muralis. Verrucaria kuusamoensis has an involucrellum usually exceeding half of the exciple, larger spores and dark lines are rather rare. Verrucaria devergens has larger spores and the involucrellum is usually absent or sometimes apical. Verrucaria epilithea and V. muralis have perithecia not leaving pits or the pits are shallow, the spores do not exceed 26 mm in length and dark lines are absent.

France, Cantal: Auf hartem Kalk bei St. Santin, 1886, F. Adelminien (B600191351!, syntype).

The specimen in B is tiny with ca. 10 perithecia, of which all but two are covered by glue. The specimen is not identifiable and the species is better to be treated as a species with unresolved status (Pykälä 2016).

[Slovenia] Carniola, Mojakrana, Aljazev dom, 1100 m, 1931, Servít (PRM-858477!, holotype?).

Prothallus not seen. Thallus white, endolithic. Perithecia 0.11–0.36 mm, immersed, leaving deep pits in the rock. Involucrellum absent. Exciple ca. 0.25 mm in diam., wall dark. Periphysoids ca. 25–35 × 2–3 mm, sparsely branching, Bagliettoa-like. Ascospores 0-septate (only few seen), 15–18 × 6–8 mm.

According to the protologue (Servít 1948), the spore size is 20–28 × 7–8 mm. The species may be related to Bagliettoa calciseda (DC.) Gueidan & Cl. Roux.

Austria, Niederösterreich, Voralpen, Bez. Lilienfeld, Gem. Kleinzell, SE von Salzerbad, Weg von Reintal zum Kruckensattel, 550–650 m alt., 29.3.2002, O. Breuss (8060) 19.990 (LI-01763881!, holotype).

Prothallus rather weakly developed, medium brown, weakly fimbriate. Thallus pale greyish-brown with frequent medium brown flecks, rimose, ca. 0.05–0.15 mm thick. Perithecia 0.22–0.38 mm, 1/2–3/4-immersed, not leaving pits to leaving shallow pits in the rock, thinly thalline covered except apex; ca. 80–100 perithecia cm². Ostiole pale brown, plane, ca. 20–60 mm wide. Involucrellum to the exciple base level, occasionally enveloping the exciple, ca. 40–60 mm thick, appressed to the exciple. Exciple 0.21–0.24 mm in diam., wall pale to dark brown. Ascospores 0-septate, (22.7–)26.1–28.1– 30.9(–33.6) × (12.1–)12.4–13.5–14.5(–15.8) mm (n = 20).

This species was erroneously reported from Finland by Pykälä (2011), but based on the ITS phylogeny, the specimen belongs to V. subjunctiva. It differs from the other Finnish specimens of V. subjunctiva by the pale exciple wall. Originally, V. alpigena was described as a species related to V. muralis, but differing by larger spores (Breuss 2008). Studying the type specimen of V. alpigena revealed that the species may not be related to V. muralis nor to the Thelidium group. It has a superficial morphological similarity to Verrucaria ahtii Pykälä, Launis & Myllys (Pykälä et al. 2017), but the spores are larger. Verrucaria alpigena may belong to the so-called Endocarpon group such as V. ahtii.

[Germany,] Alg. Alpen, Britzelmeyer (PRM-858488!, holotype?).

Prothallus not seen. Thallus whitish grey, endolithic. Perithecia 0.22–0.36 mm, 3/4–1-immersed, leaving deep pits in the rock. Involucrellum apical, ca. 60 mm thick, appressed to the exciple. Exciple ca. 0.24 mm in diam., wall dark. Ascospores 0-septate, 23–31 × 11–13 mm.

The specimen is small and only one perithecium was dissected. Our spore measurements match well with the original description (26–32 × 10–12(–14) mm, according to Servít 1948), as well as the values given by Breuss (26–32 × 10–13 mm, according to Breuss 2016). According to Servít (1948), the size of the exciple is 0.4 mm. Verrucaria bavarica is morphologically close to V. cavernarum and V. subtilis, but may differ in having a larger exciple (which was not confirmed due to the very small size of the specimen) and slightly larger spores.

[Switzerland] ad saxa dolomitica in alpe Camsciano sopra Poschiavo, Anzi nro. 364 (S-L140!, syntype).

Prothallus not seen. Thallus inconspicuous, endolithic. Perithecia 0.15–0.25 mm, 3/4–1-immersed, leaving deep pits in the rock. Involucrellum absent. Exciple ca. 0.25–0.3 mm in diam., wall black. Periphysoids ca. 30–40 × 2 mm. Ascospores 0-septate, 17–23 × 11–12(–14) mm.

The species differs from V. devergens, V. foveolata and other species treated in the Taxonomy section in smaller spores.

[Germany] an einer Sandsteinmauer in den Weinbergen bei Neuenheim, Febr. 1863, W. von Zwackh (M-0023494!, syntype?).

Prothallus not seen. Thallus pale grey, rimose to areolate, areoles 0.3–0.7 mm. Perithecia 0.22–0.26 mm, immersed in thallus. Involucrellum absent. Exciple wall pale. Periphysoids ca. 50–80 × 2.5–3 mm, branching. Ascospores 0-septate (only few seen), 20–28 × 13–14 mm.

Krzewicka (2012) treated V. carnea as a pigment-deficient mutant of V. hochstetteri and Gilbert (1996) as an albino form of V. macrostoma Dufour ex DC. However, it differs in several morphological characters from these species. Oïhénart et al. (2018) accepted V. carnea as a distinct species.

[France,] Saléve (H-NYL3038!, UPS!, probably syntypes).

Prothallus not seen. Thallus pale greyish-brown, thinly epilithic, continuous. Perithecia 0.38–0.61 mm, 1/2–3/4-immersed, leaving fairly deep to deep pits in the rock; ca. 30–60 perithecia/cm². Ostiole plane to depressed, ca. 20–60 mm wide. Involucrellum covering half of the exciple, ca. 70–180 mm thick. Exciple 0.23–0.38 mm in diam., wall black. Periphysoids long, ca. 1.5–3 mm thick. Ascospores 0-septate, 30–38 × 12–15 mm.

The species may be related to Verrucaria depressula Servít, but has larger perithecia and thicker involucrellum. The species was erroneously reported by Pykälä (2010a) from Finland.

[France] Calcaire argileux enposé au N, á 100 m au NE du pas du Bourreau Allaunch, 7.7.1951, Clauzade (PRM-858628!, syntype?).

Prothallus not seen (but, according to the protologue, “linea nigra marginatus”). Thallus grey with tiny brown flecks, thinly epilithic, continuous. Perithecia 0.25–0.45 mm, 3/4–1-immersed, leaving deep pits in the rock; ca. 70–80 perithecia/cm². Involucrellum covering half of the exciple, ca. 60–80 mm thick. Exciple ca. 0.25 mm in diam., wall black. Periphysoids ca. 35–50 × 2–2.5 mm. Ascospores 0-septate, 28–34(–38) × 12–13 mm.

The studied specimen is tiny and better material is needed to solve the identity of the species. The specimen matches in most respects with V. subjunctiva. The spores seen were narrower, but the spore size given in the protologue (Bouly de Lesdain 1950) 25–33 × 13–16 mm is similar to V. subjunctiva.

[Italy] An Kalksteinen einer Schutthalde unterhalb der Kalkwände an der Südseite des Latemar –Gebirges oberhalb Predazzo, Südtirol, 21. Aug. 1883, Arnold (H-NYL 7009!, H!, UPS-L-169663!, isotypes).

Prothallus absent. Thallus endolithic, grey. Perithecia 0.15–0.39 mm, (3/4–)1-immersed in rock, leaving deep pits in the rock. Involucrellum absent or possibly in some perithecia, small apical involucrellum. Exciple ca. 0.25–0.40 mm in diam., apex thickened, wall black, ca. 30 mm thick. Periphysoids ca. 50–70 × 2 mm, branched-anastomosing. Ascospores 0-septate, 25–30(–32) × (12–)13–16(–17) mm, perispore 1(–1.5) mm thick, persistent.

The species is rather similar to V. foveolata, but the halonate perispore seems to be persistent. This species seems not to have been validly published as the species description is missing from Arnold (1885) and Steiner (1911).

Prothallus not seen. Thallus grey, pale brown, medium brown or rarely dark brown, with a violet tinge, continuous, rimose or areolate, thallus colour may be variable within specimen, 0.05–0.2(–0.3) mm thick, contiguous conspecific thalli separated by dark lines. Perithecia 0.26–0.52 mm, (1/2–)3/4-immersed, leaving shallow to deep pits in the rock; ca. 60–120 perithecia/cm². Involucrellum apical, strongly diverging from the exciple (mainly spreading outwards away from the exciple), (40–) 50–90 μm thick. Exciple 0.25–0.4 mm in diameter, pale or dark. Periphysoids ca. 40–60 × (1–)1.5–2 μm. Ascospores 0-septate, (24–)27–35(–45) × 10–18(–20) μm, few spores 1-septate.

Based on morphology, V. depressula may belong to the Thelidium group or perhaps more probably be related to V. viridula. The type locality is in Sweden and rather close to Finland, but nevertheless, no specimens fitting with V. depressula have been found from Finland.

[Italy] ad saxa calcarea prope Veronam Mass., Anzi, Lich. Exs. minus rari Italiae superioris 377 (UPS!, syntype).

Prothallus not seen. Thallus grey, rimose to areolate, 0.2–0.4 mm thick. Perithecia 0.18–0.23 mm, immersed in thallus. Involucrellum apical, ca. 30–40 mm thick. Exciple ca. 0.4–0.45 mm in diam., pear-shaped, wall black. Ascospores 0-septate, 27–32 × 13–15 mm.

The studied specimen is conspecific with V. viridula.

[Italy,] in op. Giazza ad saxa dolomitica, 1853, A. Massalongo (VER!, syntype); Ad saxa dolomitica in oppido Giazza Prov. Veron. Massal., Massalongo Lichens Ital. Exsiccatae 250 (VER!, syntype).

Prothallus not seen. Thallus pale greyish-cream, endolithic to thinly epilithic surrounding perithecia, slightly rimose, thalli bordered by a blackish-brown line. Perithecia 0.26–0.53 mm, (1/2–)3/4-immersed, leaving deep pits in the rock; 70–100 perithecia/cm². Ostiole, pale, plane or depressed, ca. 40–150 mm wide. Involucrellum apical, 50–80 mm thick. Exciple 0.24–0.42 mm in diam., wall medium brown to blackish-brown, pale in one studied perithecium. Periphysoids ca. 40–50 × 2 mm. Ascospores 0-septate, 26–37 × 11–18 mm.

Verrucaria dolomitica and V. foveolata have been treated as separate taxa because of the presence (in the former) or absence (in the latter) of an apical involucrellum (Breuss 2004). Verrucaria dolomitica was reported as new to Finland by Pykälä (2010b). However, the Finnish specimens with and without an apical involucrellum have identical ITS sequences or the sequences differ only by a few bases. The Finnish specimens originally identified as V. dolomitica are conspecific with V. foveolata and treated as such in Stenroos et al. (2016). The Finnish specimens identified as V. dolomitica usually have endolithic thalli and no dark lines have been observed between thalli. The syntypes of V. dolomitica studied have a partly epilithic thin thallus bordered by a dark line. Furthermore, the perithecia are larger than in the Finnish specimens. Thus, V. dolomitica is apparently distinct from V. foveolata, but V. dolomitica does not occur in Finland.

[Switzerland] Helvetia (H-ACH 686!, holotype?, piece on the upper left).

Prothallus not seen. Thallus pale grey, thin, continuous, up to 0.1 mm thick. Perithecia 0.26–0.41 mm, 1/4–1/2-immersed in thallus, sometimes with thin irregular thalline cover; ca. 70–100 perithecia/cm². Ostiole inconspicuous, dark, plane or depressed, ca. 20–70 mm wide. Involucrellum slightly exceeding half of the exciple or reaching the exciple base level, 50–70 mm thick, appressed to the exciple or slightly diverging from it. Exciple 0.25–0.32 mm in diam., wall pale. Periphysoids ca. 30–40 × 1.5–2 mm, branching. Asci 75–117 × 25–37 mm, 8-spored. Ascospores 0-septate, (25.3–)26.8–29.6–32.3(–34.4) × (10.4–)11.8–12.5–13.2(–13.4) mm (n = 37).

Verrucaria epipolaea is reminiscent of rare morphs of V. kuusamoensis with a pale exciple. It differs in less immersed perithecia by not leaving pits and in the consistently hyaline exciple wall.

[Greece,] Euboea: Berg Xerowuni, ca. 1100 m alt., 1931, Rechinger (PRM-858655!, isotype).

Prothallus not seen. Thallus white to whitish-grey, endolithic. Perithecia 0.2–0.35 mm, 3/4–1-immersed, leaving deep pits in the rock. Involucrellum covering half of the exciple, ca. 100 mm thick, appressed to the exciple. Exciple ca. 0.35–0.45 mm in diam., wall black. Periphysoids ca. 40–50 × 2–2.5 mm. Ascospores 0-septate, 25–30 × 12–16 mm.

The species may be conspecific with V. viridula, but the thallus is endolithic.

[Russia,] Lapponia Rossica, 1843, F. Nylander (H!, holotype or syntype).

Prothallus not seen. Thallus grey, rimose. Perithecia ca. 0.4–0.6 mm, 1/2-immersed, leaving deep pits in the rock. Involucrellum enveloping the exciple, ca. 50–100 mm thick, thicker at apex. Exciple ca. 0.3–0.4 mm in diam., wall black. Ascospores in very poor condition, 0-septate, ca. 22–25 × 10 mm.

The specimen in H is small and in a very poor condition. Vainio (1921) reported the spore size of 15–24 × 10–18 mm. Pykälä (2010b) reported the species new to Finland. The Finnish specimen (the sequencing failed) may be rather similar to the one sectioned perithecium of the type of V. grossa, which, however, had spores in poor condition. Verrucaria grossa should be treated as a species with unresolved identity unless better type material can be located.

[Montenegro] Dalmatia mer., Herceg Novi, 80 m, 1929, M. Servít (PRM-760604!, holotype).

Prothallus not seen. Thallus white to grey, endolithic. Perithecia 0.12–0.26 mm, immersed, leaving deep pits in the rock; ca. 30–40 perithecia/cm². Involucrellum absent. Exciple ca. 0.4 mm in diam., wall black. Periphysoids ca. 35–50 × 1.5–2 mm, branched-anastomosing. Ascospores 0-septate (only few seen), 20–23 × 10–11 mm.

The spore size given in the protologue (Servít 1948) is 21–25(–32) × 12–13(–15) mm. The species differs from V. devergens and V. foveolata in smaller spores. Verrucaria devergens has smaller exciple (up to 0.35 mm). Verrucaria caesiopsila may differ in a smaller exciple and possibly in smaller spores.

Germania: Regni Würtemberg, Blabyrae, ad rupes calcareas, Hochstetter (UPS-L-708716!, holotype).

Prothallus not seen. Thallus light grey, endolithic, dark lines between contiguous conspecific thalli present. Perithecia immersed, leaving deep pits in the rock. Involucrellum absent. Exciple 0.32–0.4 mm in diam., longer than wide, wall black, rather thin. Asci ca. 110–125 × 30–38 mm. Ascospores 0-septate, (25–)26–30(–35) × 16–20 mm.

The specimen is small and the description above is based on only one perithecium dissected. Verrucaria hochstetteri was reported from Finland by Pykälä (2007). However, all the Finnish specimens have narrower spores (max. 18 mm broad) than in the type specimen of V. hochstetteri and no dark lines between contiguous conspecific thalli. Thus, they apparently do not belong to V. hochstetteri, but to V. foveolata.

Not in H-NYL, protologue: “in Gallia passim (Ejus statum ochraceo-tinctum, E Cebennis inferioribus in hb. Mougeot vidi)”.

The type material has not been located (possibly in Paris). Nylander had a very wide circumscription for V. integra. Specimens identified by Nylander as V. integra in H-NYL represent several species of Verrucaria. Thus, the identity of V. integra cannot be solved without studying the type material. Two old records of this species have been reported from Finland (Vainio 1921), but these specimens belong to V. viridula. Based on Vainio’s interpretation of V. integra, the species may be conspecific with V. viridula.

[Switzerland] ad dolomit supra Poschiavo, Anzi (H-NYL 3384!, syntype).

Prothallus absent. Thallus inconspicuous, endolithic. Perithecia 0.18–0.23 mm, 3/4–1-immersed, leaving deep pits in the rock; ca. 100–110 perithecia/cm². Ostiole depressed, ca. 20–50 mm wide. Involucrellum absent (?). Exciple ca. 0.2 mm in diam., wall dark. Ascospores 0-septate, ca. 17–21 × 11–12 mm.

The studied specimen may be a tiny syntype. Nylander has annotated to the specimen: spores 18–24 × 11–14 mm. Verrucaria integrella may be synonymous with V. caesiopsila as often stated in literature (e.g. Clauzade and Roux 1985; Santesson et al. 2004).

[Germany] an Dolomitfelsen in Laubwäldern bei Eichstätt (Baiern), F. Arnold, Hepp, Flechten Eur. 692 (UPS-L-069713!, syntype).

Prothallus not seen. Thallus white, endolithic to thinly epilithic. Perithecia 0.2–0.3 mm, 3/4–1-immersed, leaving deep pits in the rock, surrounded by a thalline collar, ca. 50–120 perithecia/cm². Ostiole inconspicuous, dark, depressed, ostiolar depression up to 100 mm wide. Involucrellum apical, 40–70 mm thick, appressed to the exciple. Exciple 0.17–0.25 mm in diam., wall dark. Periphysoids ca. 30 × 1.5 mm. Ascospores 0-septate, (17–)18–21 × (7–)8 mm.

This species differs from V. subtilis in smaller spores. The specimen H-NYL 7012 does not belong to the type material because it has too large spores (25–33 × 12–16 mm).

[Italy,] in op. Tregnago – Viacara (VER!, syntype).

Prothallus not seen. Thallus pale brownish-grey, continuous to rimose. Perithecia 0.12–0.21 mm, 3/4–immersed in thallus. Involucrellum apical, ca. 40–50 mm thick, appressed to the exciple. Exciple 0.27–0.33 mm in diam., wall black. Periphysoids ca. 40–45 × 2 mm. Ascospores 0-septate, 28–31 × 12–15 mm.

The syntype specimen studied is probably conspecific with V. viridula.

?, protologue: “Jugoslavia, Pulac pr. Rijeka (Fiume), 250 m, dolom., Schuler (P)”.

The type material was not located. Verrucaria mimicrans was reported from Finland by Pykälä and Breuss (2008), but the specimen belongs to V. subtilis. In the original description, the spore size of V. mimicrans is 25–31 × 12–15 mm (Servít 1950) which exceeds the values of V. subtilis. Thus, V. mimicrans may be distinct from V. subtilis, but not present in Finland.

[Montenegro,] Lovcen, Veterni mlin, 1400 m, 1929, M. Servít (PRM-859152!, holotype).

Prothallus not seen. Thallus grey with frequent tiny brown flecks, endolithic. Perithecia 0.18–0.26 mm, 3/4(–1)-immersed, leaving deep pits in the rock; ca. 60–80 perithecia/cm². Involucrellum reaching the exciple base or enveloping the exciple, in the latter case diffusely pigmented under the exciple, ca. 70–110 mm thick, appressed to the exciple. Exciple ca. 0.20–0.22 mm in diam., wall dark. Periphysoids ca. 20–25 × 2.5–3 mm. Ascospores 0-septate (only few seen), 20–25 × 11–14 mm.

The species differs from the species of the V. subtilis complex by thicker involucrellum and shorter spores. Verrucaria samosensis Servít has thinner involucrellum and shorter spores.

[Czech Republic,] Moravia, Kopřivnice, Piskovnice, 490 m alt., 1922, Suza (PRM-760594!, syntype).

Prothallus not seen. Thallus whitish-grey with abundant medium greenish-brown punctae, endolithic, a dark line between contiguous conspecific thalli. Perithecia 0.23–0.35 mm, 3/4–1-immersed, leaving deep pits in the rock, surrounded by a thalline collar; ca. 40–60 perithecia/cm². Involucrellum apical. Exciple ca. 0.26 mm in diam., wall brown. Ascospores 0-septate, 20–25 × 9–12 mm.

Perithecia are mostly over-mature. One perithecium was sectioned. V. moravica may be rather similar to V. subtilis, but differs in the presence of dark lines between contiguous conspecific thalli. In the original description, the spore length was reported to be more variable: 18–28 × 9–12 (Servít 1948). In V. transfugiens Zschacke, the involucrellum is absent.

[France] Salève, J. Müller (M-0193432!, holotype).

Prothallus not seen. Thallus pale brown with a violet tinge, continuous, hemi-endolithic, contiguous conspecific thalli separated by dark lines. Perithecia 0.38–0.46 mm, 3/4-immersed, leaving deep pits in the rock; ca. 30–50 perithecia/cm². Involucrellum apical, ca. 50–60 mm thick, appressed to the exciple. Exciple ca. 0.34–0.35 mm in diam., wall black, ca. 25 mm thick. Periphysoids ca. 50–80 × 1–1.5 mm. Ascospores 0-septate, 32–41 × 12–15 mm.

The species is morphologically close to V. depressula or may even be conspecific.

[France] Gallia, Sevres (M-0193237!, holotype).

Prothallus not seen. Thallus greenish-grey with green flecks, continuous, ca. 0.1–0.3 mm thick. Perithecia 0.12–0.32 mm, immersed, leaving deep pits in the rock; ca. 80–100 perithecia/cm². Involucrellum absent. Exciple ca. 0.27–0.41 mm in diam., higher than broad, often pear-shaped, wall dark brown. Periphysoids ca. 40–60 × 2–2.5 mm, branched-anastomosing. Asci 85–106 × 25–29 mm, 8-spored. Ascospores 0-septate, 18–23 × 12–14 mm.

The species differs from V. viridula by shorter spores and absence of an involucrellum.

[Germany] Eichstätt, ober dem Tiefenthale, 2. 1887, Boll (M-0204594!, holotype).

Prothallus not seen. Thallus grey, endolithic. Perithecia 0.08–0.21 mm, immersed, leaving deep pits in the rock; ca. 60–100 perithecia/cm². Involucrellum absent. Exciple ca. 0.19–0.24 mm in diam., wall medium brown to dark brown, apex often thickened. Periphysoids ca. 15–30 × 2–2.5 mm. Asci ca. 61–69 × 20–21 mm, 8-spored. Ascospores 0-septate, 18–23 × 8–11 mm.

The species may differ from V. caesiopsila by narrower spores and shorter periphysoids. Verrucaria koerberi has an apical involucrellum and narrower spores.

Jugoslavia, Lovčen, Sanatorium, 1240 m, 1929, M. Servít (PRM-858454!, holotype?).

Prothallus not seen. Thallus grey with brown punctae, endolithic, contiguous conspecific thalli separated by dark lines. Perithecia 0.15–0.2 mm, 3/4(–1)-immersed, leaving deep pits in the rock; ca. 80–240 perithecia/cm². Involucrellum absent. Exciple ca. 0.21–0.24 mm in diam., wall pale brown to medium brown, apex thickened to ca. 40–50 mm thick. Ascospores 0-septate 16–24 × 10–13(–14) mm.

The species is rather similar to V. transfugiens, but has a paler exciple wall and slightly larger spores.

[Austria,] Dolomit … Grosser Rettenstein bei Kizbühel im Tirol, 1869, Arnold (PRM-858456!, isotype).

Prothallus not seen. Thallus pale brown, epilithic, thin, continuous. Perithecia 0.15–0.23 mm, (3/4–)1-immersed, leaving deep pits in the rock. Involucrellum absent or apical, ca. 70–90 mm thick. Exciple ca. 0.22–0.25 mm in diam., wall blackish-brown, the apex is strongly thickened when the involucrellum is absent. Ascospores 0-septate, 27–37 × 12–15 mm.

The species may fall within the variation of V. foveolata, although it has an epilithic pale brown thallus.

[Croatia] Dalmatien: Schlossruine Vrlika a.d. … Granuga, an Kalk… c. 550 m, 5.7.1911, J. Baumgartner 4250 (W-4250!).

Prothallus not seen. Thallus endolithic, grey. Perithecia 0.15–0.34 mm, immersed, leaving deep pits in the rock; ca. 100–130 perithecia/cm². Involucrellum absent. Exciple ca. 0.35–0.5 mm in diam., longer than wide, often pear-shaped, apex thickened, wall black. Periphysoids ca. 50–80 × 2 mm. Ascospores 0-septate, 26–35 × 12–14 mm.

Material similar to V. periphysata has not been observed in Finland. The exciple of the species is larger than in V. foveolata (0.2–0.4 mm in diam.). The periphysoids may also be longer.

[Italy] 87. Dolomitfelsen in der Schlernklamm ober … in Süd Tirol, 7.1867, Arnold (H-NYL 3208!, H-NYL 3209!, syntypes).

Prothallus absent. Thallus endolithic, grey with a violet tinge, a dark line between contiguous conspecific thalli present, 0.15–0.22 mm wide. Perithecia 0.21–0.44 mm, immersed in rock, leaving deep pits in the rock. Ostiolar depression large. Involucrellum absent or possibly in some perithecia, small apical involucrellum. Exciple ca. 0.4 mm in diam., apex thickened to ca. 60–80 mm, wall black. Periphysoids ca. 50–60 × 2 mm. Ascospores 0-septate, ca. 26–34 × 16–20 mm, perispore ca. 1–1.5 mm thick.

The perithecia of the syntypes in H-NYL are mainly over-mature. The spore size annotated by Nylander to the specimen is larger (40–48 × 23–26 mm) than the few spores measured by us. Servít (1948) reported high variation in the spore size: 20–45 × 18–26 mm. Verrucaria praecellens seems to be characterised by broad spores and a persistent perispore. Verrucaria cryptica has narrower spores. V. praecellens has been synonymised with V. hochstetteri (Krzewicka 2012), but it may differ by persistent perispores and larger spores.

Slovakia, in valle fl. Hnilec, pr. R. Ztratená, 800 m alt., calc., 1933, Suza (PRM 858074!, syntype).

Prothallus not seen. Thallus grey, endolithic to semi-endolithic. Perithecia 0.25–0.33 mm, 3/4-immersed, leaving deep pits in the rock, usually surrounded by a thalline collar or is covered by a thin thalline layer except for the apex. Ostiole pale, plane, ca. 20–50 mm wide. Involucrellum covering half of the exciple, ca. 50–70 mm thick, diverging from the exciple. Exciple ca. 0.3–0.33 mm in diam., wall pale brown. Periphysoids ca. 25–30 × 2–2.5 mm. Ascospores 0-septate, 27–38 × 12–15 mm.

Verrucaria pustulifera differs from V. subjunctiva in a pale brown exciple and shorter periphysoids. The involucrellum is also smaller than usually in V. subjunctiva. Verrucaria kuusamoensis has smaller spores.

[France] Reculet, Jan. 1855, J. Müller (M-0220250!, holotype).

Prothallus not seen. Thallus pale brown, epilithic, thin, continuous. Perithecia 0.38–0.55 mm, 1/2–3/4-immersed, leaving deep pits in the rock; ca. 30–40 perithecia/cm². Ostiole tiny, inconspicuous, dark, plane, often surrounded by a projecting neck up to ca. 150 mm wide. Involucrellum absent. Exciple ca. 0.38–0.45 mm in diam., wall dark, ca. 30–40 mm thick, apex thickened to 70–100 mm thick. Periphysoids ca. 50–60 × 1.5–2 mm, branched-anastomosing. Ascospores 0-septate, 25–30 × 13–16 mm.

The species is rather similar to V. foveolata, but may differ by slightly larger perithecia and an epilithic pale brown thallus.

[Greece,] Samos, Vathy, Rechinger (PRM-858434!, holotype).

Prothallus not seen. Thallus whitish-grey, endolithic to thinly epilithic, occasionally irregularly rimose around perithecia. Perithecia 0.22–0.28 mm, (1/2–)3/4-immersed, leaving shallow to deep pits in the rock; ca. 70–80 perithecia/cm². Involucrellum enveloping the exciple, 40–50 mm thick. Exciple 0.19–0.28 mm in diam., wall black. Periphysoids ca. 50–60 × 2–2.5 mm. Ascospores 0-septate, ca. 21–25 × 11–13 mm.

According to the protologue, the spores may be larger: 20–29 × 9–15 mm (Servít 1948). The species differs from V. bifurcata by longer periphysoids and possibly by slightly shorter, but broader spores.

[Italy,] avi in op. Avesa ([Monte] Ongarine) ad saxa putrida eocenica (VER!, syntype).

Prothallus not seen. Thallus whitish-grey, endolithic to semi-endolithic, a black line between thalli present. Perithecia 0.16–0.23 mm, immersed, leaving deep pits in the rock. Involucrellum absent. Exciple ca. 0.26 mm in diam., wall brown. Ascospores 0-septate, 24–33 × 12–18 mm.

Krzewicka (2012) treated V. saprophila as a synonym of V. hochstetteri. However, V. hochstetteri has a larger exciple and broader spores. The species differs from V. foveolata with the presence of a dark line. Verrucaria dolomitica has larger perithecia and an apical involucrellum.

Not seen. Protologue: “Italia, in Valle Bisagno prope Genuam, loco Prato, supra rupem calcaream colore fuscorufo tinctam. leg. Sbarbaro, 1946”.

The type material of V. sbarbaronis has not been located. Breuss (2008a) treated V. sbarbaronis as a species rather similar to V. lacerata (which is here considered conspecific with V. subjunctiva), but with clearly smaller spores (20–26 × 11–15 mm). Such specimens have not been found from Finland.

[Austria], Kalksteine des Serlosgipfels 8200’ Matrei-Tirol, 7. 1869, Arnold (M-0193173!, holotype).

Prothallus not seen. Thallus grey to pale brown, endolithic, somewhat inconspicuous. Perithecia 0.12–0.22 mm, immersed, leaving deep pits in the rock; ca. 60–100 perithecia/cm². Involucrellum absent. Exciple ca. 0.2 mm in diam., wall pale to pale brown, apex dark, thickened. Ascospores 0-septate, (23.2–)23.9–24.7–25.4(–25.5) × (12.7–)12.8–13.7–14.6(–15.1) mm (n = 15).

The specimen is rather poor. The species differs from V. foveolata by a pale exciple wall, shorter spores and perhaps by a smaller exciple. Verrucaria caesiopsila has smaller spores and a dark exciple wall.

Slovakia, Liptovskě hole, Zuberec, Osobita, 1650–1680 m, 1935, Suza (PRM-765231!, syntype).

Prothallus not seen. Thallus white or grey, endolithic. Perithecia 0.25–0.35 mm, 1/2–3/4(–1)-immersed, leaving shallow to deep pits in the rock. Involucrellum reaching the exciple base, ca. 70–90 mm thick, appressed to the exciple or slightly diverging from the exciple. Exciple ca. 0.15–0.25 mm in diam., wall pale. Periphysoids ca. 25 × 2–2.5 mm. Ascospores 0-septate, few spores 1-septate, ca. 20–27 × 9–10 mm, not well developed.

Verrucaria slovaca may possibly belong to the V. subtilis complex, but similar specimens have not been found in Finland. The spore size given by Servít (1950) is 24–30 × 9–11 mm. Breuss (2016) apparently found better-developed spores than in this study: (22–)24–27(–28) × (7.5–)9–11–(12) mm.

[Italy], Auf Kalkconglommerat in Villa Lagarina bei Roveredo in Südtirol, 1.5.1883, P. Strasser (M-02039301!, holotype).

Prothallus not seen. Thallus whitish-grey, endolithic. Perithecia 0.15–0.38 mm, (3/4)–1-immersed, leaving deep pits in the rock. Involucrellum apical, ca. 50–90 mm thick, appressed to the exciple. Exciple ca. 0.22–0.26 mm in diam., wall pale brown to dark brown. Periphysoids ca. 30–50 × 1.5–2.5 mm, branching. Asci ca. 88–95 × 26–28 mm, 8-spored. Ascospores 0-septate, (23.6–)24.5–26.6–28.8(–30.2) × (10.1–)10.4–11.4–12.4(–13.7) mm (n = 17).

The species may differ from the V. devergens and V. subtilis complexes by mostly fully immersed perithecia and from the V. subtilis complex by slightly larger perithecia and a thicker involucrellum.

Deutschland. Thüringen, Jonastal bei Arnstadt, alt. 350–400 m, co-ord. 10°55'E, 50°49'N. An Muschelkalkplättchen, 7.7.1907, G. Lettau (B-600025730!); Deutschland.Sachsen-Anhalt: Vorland des Nord-Ost-Harzes, Steinbruch am Hackel. co-ord. 11°19'E, 51°53'N, 1910, H. Zschacke 4664 (B-600194785!); Deutschland.Sachsen-Anhalt: Harz-Vorland, Ostseite des Hackels. co-ord. 11°19'E, 51°53'N, 1.2.1906, H. Zschacke 4664 (B-600194786!); Deutschland. Thüringen: Dosdorfer Haart, unweit Arnstadt, alt. 450 m, an Muschel Kalk-Felsbänken, accomp. Tichothecium erraticum, Caloplaca lactea 11.9.1907, G. Lettau 614 (B-600194783!); Deutschland. Thüringen: Dosdorfer Haart, unweit Arnstadt, alt. 450 m, an Muschel Kalk-Felsbänken, 1907?, G. Lettau (B-600194781!). Syntypes.

For the description of the species, see Pykälä (2016). V. transfugiens has been reported from Finland by Pykälä and Breuss (2008), but the specimens belong to V. subtilis (Stenroos et al. 2016).

[Italy,] S. Leonardo, L. Tonini (VER!, syntype); ad saxa eocenica circa urbem Veronam (S. Leonardo), leg. Tonini, Massalongo Lichenes Ital. Exsiccatae 8 (VER!, syntype); Massalongo, Lich. Ital. exs. 8 (UPS!, syntype).

Prothallus absent. Thallus greenish-grey or grey with some brown pigmentation, epilithic, rimose, ca. 0.2–0.3(–0.4) mm thick. Perithecia 0.12–0.32 mm, 3/4–1-immersed in thallus. Involucrellum apical, ca. 60–70 mm thick. Exciple ca. (0.2–)0.3–0.5 mm in diam., often longer than broad, wall dark. Ascospores 0-septate, 27–35 × 11–15 mm.

The type material of the species is morphologically similar to V. viridula and, based on the morphological similarity, the species is likely to be conspecific with V. viridula.