*Abrothallus aff. caerulescens Kotte

Description – Ascomata apothecia, superficial on host thallus, emarginate and strongly convex, 0.2–0.3 mm in diam.; discs black, epruinose. Hymenium ca. 50 µm, greenish in upper part; epihymenium greenish brown, K+ green; hypothecium brownish. Ascospores brown, 1-septate, 14–15 × 5 µm. Vegetative hyphae of the examined specimen I– (see comments).

Host – Xanthoparmelia conspersa (Ach.) Hale (thallus).

Distribution and habitat – Abrothallus caerulescens is a commensal fungus that grows exclusively on the thalli of yellow-green Xanthoparmelia species and, therefore, is associated with siliceous rocks. It is widely distributed, being reported from Northern and Southern America (Diederich, 2004), the Middle East (Seaward et al., 2008) and many regions of Europe (e.g., Czyżewska & Kukwa, 2009; Kondratyuk et al., 2021; Roux et al., 2020; Savić et al., 2006; Schiefelbein et al., 2017; Varga et al., 2021; Westberg et al., 2021; Zhurbenko & Notov, 2015).

Comments – Abrothallus caerulescens was described by Kotte (1909) based on relatively large ascospores and positive iodine reaction of vegetative hyphae, which was even pointed out in the epithet of the species. However, the taxonomical value of this feature is debatable, as at least some specimens found on Xanthoparmelia were reported as I–. Diederich (2003, 2004) treated all Abrothallus specimens on yellow-green Xathoparmelia, both I+ and I–, as A. caerulescens, while Ihlen and Wedin (2008) included I– morphs to another species, A. parmeliarum. Cole and Hawksworth (2001) described I– specimen found in Canada as a new species, A. tulasnei, reported later also from Turkey (Halici & Cansaran Duman, 2008) and New Zealand (Hafellner & Mayrhofer, 2007). Apart from the I-reaction of mycelium, A. tulasnei differs from A. caerulescens by a slightly taller hymenium and bigger ascospores (Cole & Hawksworth, 2001).

The material collected in the Karkonosze Mountains matches the descriptions of Abrothallus caerulescens, except for the iodine reaction of the hyphae. It was found on a summit of the exposed granite rock surrounded by a spruce forest in the lower montane belt. A. caerulescens has not been reported from this mountain range until now; in Poland, it is known from scattered localities in the Carpathians (Kukwa & Czarnota, 2006), Sudety Foreland (Kossowska & Szczepańska, 2013) and the lowland parts of the country (Czyżewska et al., 2008; Kukwa & Flakus, 2009; Kukwa & Jabłońska, 2008; Kukwa & Kowalewska, 2007).

Specimen examined: ATPOL grid square Ea–79, Sudety Mts, Karkonosze Mts, Pogórze Karkonoskie Foothills, Patelnia rock on the slope of the Grabowiec Mt., 50.8039°N, 15.7331°E, alt. 725 m, on Xanthoparmelia conspersa growing on granite, 7.07.2013, leg. M. Kossowska, herb. Kossowska 1367.

*Cercidospora parva Hafellner & Ihlen

Description – Ascomata perithecia, immersed in the host thallus, black, 0.1–0.2 mm in diam. Peridium in the upper part greenish blue, in the lower part, hyaline. Paraphysoids thin, ca. 2 µm, branched and anastomosing. Asci cylindrical, thin-walled, 45–63 × 7–10 µm. Ascospores arranged ± uniseriately, deltoid-ellipsoid, 1-septate, with the upper cell slightly bigger than the lower, hyaline, 12–15 × 4–5 µm. The fungus causes the darkening of infected lichen thalli to grey or dark olive.

Host – Baeomyces rufus (Huds.) Rebent. (thallus)

Distribution and habitat – This is a rare lichen parasite, growing exclusively on Baeomyces (B. rufus and B. platyphyllus). It is known mainly from northern regions of Europe and Asia: Norway, Iceland, arctic Russia (Taymyr Peninsula), and Scotland (Ihlen, 1998; von Brackel, 2010a; Zhurbenko, 2009). In Central Europe, this species has been previously reported only in southern Germany (von Brackel, 2009, 2010b). Here, it is reported as new for Poland.

The first Polish record of Cercidospora parva was located in the alpine belt of the Karkonosze Mts. The host lichen Baeomyces rufus grew there on bare siliceous soil in the loose plant community dominated by Festuca airoides and Calluna vulgaris.

Comments – Polish specimen of Cercidospora parva strictly corresponds to the species description given by Ihlen (1998). This is the only known member of the genus Cercidospora, parasitizing Baeomyces spp. It is closely related to C. trypetheliza (Nyl.) Hafellner and Obermayer infecting thalli of another terricolous lichen, Arthrorhapis alpina. The main differences include the pigment of the upper part of the peridium and the size of ascomata, asci, and ascospores (Ihlen, 1998). Because both hosts may grow together and the distinguishing features between these two Cercidospora species are not always clear, Zhurbenko (2009) suggested their taxonomic re-examination. However, C. tryptotheliza is a rare lichenicolous fungus, in Europe known only from Spitsbergen, Faroe Islands, Scandinavia, and high elevations of the Alps (Hafellner & Obermayer, 1995; Zhurbenko & von Brackel, 2013). Its range is limited by the arctic-alpine type of distribution of the host.

Specimen examined: ATPOL grid square Ea–88, Sudety Mts, Karkonosze Mts, above the Śnieżne Kotły glacial cirques, 50.7794°N, 15.5538°E, alt. 1477 m, on the soil in high-mountain grassland Carici-Festucetum airoidis, 08.2015, leg. B. Wojtuń & L. Żołnierz, herb. Kossowska 1516.

Porpidia flavocruenta Fryday & Buschbom

Description – Thallus crustose, rather thick, cracked, yellow-orange, surrounded by a thin, black prothallus. Apothecia large, to 2 mm in diam., sessile, with persistent proper margin, becoming flexuose in mature apothecia; discs black, slightly pruinose. Exciple orange-brown to brown, containing K+ crimson pigment. Epihymenium olive-green to pale olive-brown; hymenium hyaline, ca. 110 µm tall; hypothecium dark brown. Ascospores 8 per ascus, hyaline, 16–17 × 7–8 µm. No lichen substances detected by TLC (see also Fryday, 2005).

Distribution and habitat – Porpidia flavocruenta is an epilithic species growing on various siliceous rocks. It seems to be widespread in Europe, being known from many sites in the British Isles, as well as from scattered localities in Scandinavia, Svalbard, Harz Mountains, Sudetes, and Alps (Fryday, 2005; Jabłońska, 2012; Øvstedal et al., 2009; Schiefelbein et al., 2017). It has also been reported from Alaska (Fryday, 2005) and Newfoundland (McCarthy & Fryday, 2014) in the northern part of North America.

Comments – Porpidia flavocruenta in Poland occurs exclusively in the Karkonosze Mountains. So far, it has only been found on basalt (on the so-called „basalt vein”) in Mały Śnieżny Kocioł glacial cirque (Jabłońska, 2010, 2012; Kossowska et al., 2016). Here, it is reported from a new site on the slope of Śnieżka Mt. in the eastern part of the range. The lichen grew there on a metal-enriched hornfels stone among the rush sward of the alpine belt, together with Lecidea soralifera, L. intricata, L. polytropa, and Rhizocarpon geographicum.

Porpidia flavocruenta belongs to the macrocarpa subgroup in a Porpidia macrocarpa group of species, characterized by thick excipular hyphae and a secondary metabolite chemistry of the stictic/norstictic acid chemosyndrome or no substances (Fryday, 2005). The features that make it easy to distinguish include the truly orange thallus (not rusty red due to iron compounds, as sometimes occurs in other members of the group), and the presence of an unidentified pigment in the exciple, realising a K+ intense crimson solution. A similar pigment occurs also in P. nigrocruenta, which, however, possesses a grey thallus. The also orange P. flavicunda differs in lack of the mentioned pigment in the exciple and the presence of stictic and/or norstictic acids in the thallus (Fryday et al., 2009).

Specimen examined: ATPOL grid square Eb–80, Sudety Mts, Karkonosze Mts, east slope of Śnieżka Mt., 50.7374°N, 15.7414°E, alt. ca. 1570 m, on hornfels, 6.08.2021, leg. M. Kossowska, herb. Kossowska 1622.

Porpidia thomsonii Gowan

Description – Thallus crustose, rather thin, continuous to slightly areolate, pale grey with a beige tinge. Apothecia frequent, ca 0.6–1 mm in diam., sessile, surrounded by a thick and tumid proper margin; discs black, epruinose. Exciple with blue-black cortex, sharply contrasting with the paler, brown medulla, composed of thick hyphae. Epihymenium olive-brown; hymenium hyaline, ca 110 µm tall; hypothecium dark brown, distinctly darker than exciple. Ascospores 8 per ascus, hyaline, 17–20 × 7–9 µm. Thallus K+ yellow to orange, Pd+ orange. Stictic acid as a main secondary metabolite detected by TLC.

Distribution and habitat – Porpidia thomsonii is an epilithic species, growing on siliceous rocks in exposed high-altitude situations (Fryday et al., 2009). It is probably widespread but not distinguished and undercollected. Known localities include arctic and hemiarctic parts of North America (Gowan, 1989; Hansen, 2002), as well as Scandinavia (Gowan & Ahti, 1993; Øvstedal et al., 2009), the British Isles (Fryday, 2005) and mountainous regions of Central Europa (Jabłońska, 2012).

Comments – This species was reported from Poland only by Jabłońska (2012) and Matura (2020). To date, only single localities in the Carpathians (Tatra Mountains, Beskid Sądecki Mountains) and the eastern part of the Sudetes (Śnieżnik Massif) have been known. The reported site in the Karkonosze Mountains is the first one in the Western Sudetes. The lichen grew on a granite stone within the boulder field on Wielki Szyszak (Vysoké Kolo) Mt., in severe conditions of the alpine belt.

Porpidia thomsonii is a species characterized by features that are intermediate between P. macrocarpa and P. crustulata, concerning apothecia and ascospore size, the height of hymenium, and width of excipular hyphae (Fryday, 2005). Therefore, its separation may be difficult and cause confusion. The most distinct feature allowing us to distinguish it seems to be the two-color exciple, with a rather thick, blue-black cortex and contrasting pale brown medulla.

Specimen examined: ATPOL grid square Ea–88, Sudety Mts, Karkonosze Mts, Wielki Szyszak (Vysoké Kolo) Mt., 50.7770°N, 15.5678°E, alt. 1507 m, on granite, 1.08.2008, leg. M. Kossowska, herb. Kossowska 1551.

Rhizocarpon cinereovirens (Müll. Arg.) Vain.

Description – Thallus crustose, cracked-areolate. Areoles small, flat to convex, pale grey with a brownish tinge. Apothecia frequent, black, sessile, with persistent, thin proper margin, 0.3–0.6 mm in diam. Exciple poorly developed, K–. Epihymemium olive-black, with crystals dissolving in K; hymenium hyaline, 70 µm tall; paraphyses branching and anastomosing; hypothecium dark brown. Ascospores 8 per ascus, 1-septate, hyaline, 13–15 × 6–7 µm, halonate. Thallus K+ yellow, Pd+ red, norsitcitc acid detected by TLC (see also Fryday, 2002).

Distribution and habitat – Rhizocarpon cinereovirens is a species of circumboreal distribution, known from many regions in Western, Northern and Central Europe (e.g., Fryday, 2002; Liška & Palice, 2010; Urbanavichus & Urbanavichene, 2018; Wirth et al., 2013) as well as from North America (e.g., Fryday, 2002; Talbot et al., 2007; Thomson, 1967), Russian Arctic (Andreev et al., 1996) and Asian Far East (Bi et al., 2022; Ezhkin & Schumm, 2018; Inoue et al., 2007). It inhabits exposed siliceous rocks, mainly in cool and humid climate conditions (Fryday, 2002; Wirth et al., 2013).

Rhizocarpon cinereovirens is one of the rarest elements of Polish lichen biota. It is known only from the Karkonosze Mountains (Eitner, 1911, see comments below) and a single locality in the High Tatra Mountains (Węgrzyn, 2008, 2009). The species was also reported from the Świętokrzyskie Mountains by Halicz and Kuziel (1966). However, its presence in this area is questioned (Cieśliński, 1991; Łubek, 2007). The only lowland record on a granite boulder in Rościszowice near Wrocław (Eitner, 1896, as Catocarpus seductus) also raises doubts.

Comments – Rhizocarpon cinereovirens was previously reported from the Karkonosze Mountains only by Eitner (1911, as Catocarpus seductus and C. seductus f. turgidus), who found it above the Pod Łabskim Szczytem shelter house in the western part of the mountain range and in upper parts of two glacial cirques, Mały Staw and Łomniczka, in the eastern part. Since then, this species has not been recorded. The new site is located in the western part of the range, below the summit of Wielki Szyszak (Vysoké Kolo) Mt., on granite boulders in the alpine belt.

Rhizocarpon cinereovirens is a member of the Rhizocarpon hochstetteri group, distinguished by non-yellow thalli and hyaline, one-septate ascospores (Fryday, 2002). The diagnostic traits that allow us to recognize this species are K+ orange or red and Pd+ yellow or orange reactions of thalli due to the presence of norstictic and/or stictic acids. The other members of Rh. hochstetteri group with similar chemistry are Rh. glaucescens and Rh. discoense. The latter is known so far only from Greenland and differs in well-developed, K+ purple exciple (Fletcher et al., 2009; Fryday, 2002). Rhizocarpon glaucescens occurs in a subnival belt of the Tatra Mountains (Flakus, 2014); it differs from Rh. cinereovirens in K+ purple exciple and slightly smaller ascospores (Fryday, 2002).

Specimen examined: ATPOL grid square Ea–88, Sudety Mts, Karkonosze Mts, Wielki Szyszak (Vysoké Kolo) Mt., 50.7771°N, 15.5677°E, alt. 1508 m, on granite, 1.08.2008, leg. M. Kossowska, herb. Kossowska 1536, 1559.