[BGBM-Logo] Lichen determination keys
- Pertusaria in Europa and the Mediterranean -
[BGBM-Foto klein]

Compiled identification key
to the genus Pertusaria and some confusible taxa
in Europe and the Mediterranean

modified after Poelt (1969), with additions and corrections; figures before the species refer to recent literature; key includes uncertain species and provisional names! The genus Pertusaria is incompletely known, particularly in the Mediterranean, and this key does not intend to solve the problems, it only wants to bundle the available information.

1a On rock, bark or wood --- 2
1b
On soil or detritus on soil, usually arctic-alpine --- 143

2a Thallus, when fully developed, with apothecia, which may be sometimes with poorly developed hymenium and superficially soralium-like; additionally soralia or isidia may be present --- 3
2b
Thallus normally without apothecia; soralia, isidia or nodulose excrescences mostly present --- 90

3a Ascospores dark at maturity ("Melanaria") --- 4
3b
Ascospores persistently colourless (Pertusaria s.str.) or ascocarps usually absent --- 8

4a Ascospores 1/ascus, c. 150-240 x 50-90 Ám --- 5
4b
Ascospores 2-4/ascus, smaller --- 6

5a Ascospores 160-240 x 60-90 Ám, finally completely greenish grey; thallus whitish grey, smooth, more or less rimose-areolated, areoles 1-2.5 mm wide; fertile warts not clearly differentiated, discs punctiform, black, to 40/areole; on rock, E Pyreneans, Corsica, Macedonia --- P. spilomantha Nyl.
5b Ascospores c. 150-180 x 50-70 Ám, pale brown, with reticulate striae;. thallus pale grey, continuous, warty; thallus P-, K-, C-, KC-, UV-; indet. fatty acids; apothecia becoming crater-like, lecanorine, abundant and confluent, basally constricted, 1-2 mm diam.; disc lilac-brown, flat to concave, white-pruinose; on Quercus tree base in Spain --- 3/P. sp. 2 (Giralt 1996)

6a Apothecia in more or less clearly delimited, basally constricted, 1-2 mm wide fertile warts; discs dense, united in discs of 2nd order surrounded by thalline margin; thallus thick, brownish grey, rimose-areolated; norstictic, gyrophoric, connorstictic acids; ascospores 110-160 x 45-95 Ám; Greece --- P. pentelici J.Steiner
6b Apothecia not in fertile warts or in poorly delimited fertile warts; thallus grey, grey-whitish or sometimes creamy white --- 7

7a Thallus granularly papillose, scabrid, more or less rimose-areolated, 1-1.5 mm thick; papillae semiglobose, about 0.1 mm wide and high; discs with 2-5 together, immersed; ascospores 96-160 x 50-85 Ám, with thick, colourless wall and dark, K+ violet content; on rock, Canary Islands --- P. urceolaria Nyl.
7b Thallus smooth to rugulose, more or less rimose-areolated, often granular with isidia-like, fragile, c. 0.1 mm diam. papillae leaving sorediate scars; thallus K+ orange-red, with norstictic acid; discs with several together, immersed, with slightly open, brownish black, very irregular and much divided discs; ascospores grey- or olive-black, K+ violet, 2(-4) per ascus, c. 80-100 x 55-85 Ám, outer surface minutely pitted; on siliceous rock, Western Europe, ?South Tyrol --- 4/P. lactescens Mudd

8a (3) Apothecia when fully developed with distinctly widened discs, not perithecium-like --- 9
8b
Apothecia persistently perithecium-like, with punctiform discs (ostioles), one or several in each fertile wart --- 47

9a Fertile warts soralium-like, with granularly laciniate, more or less sorediate margin and granularly pruinose discs, often with degenerated hymenium; ascospores 1-2/ascus, often poorly developed --- 10
9b
Fertile warts not soralium-like, with smooth, not pruinose or slightly mealy, initially often punctiform discs; ascospores 1-8/ascus --- 33

10a On rock --- 11
10b
On bark or wood --- 19

11a Thallus K+ yellow turning red --- 12
11b
Thallus K- or +yellowish --- 14

12a Ascospores 1/ascus; norstictic acid present --- 13
12b
Ascospores 2/ascus, c. 120-150 x 50-60 Ám; norstictic acid absent, salazinic acid and fatties present; Aegean --- P. parotica Sipman

13a Thallus with norstictic acid and sometimes? with salazinic, fatty acids and xanthone, rather thick, more or less grey, warty-papillose, the warts with sorediate openings; fertile warts to about 1.5 mm wide with 1-4 blackish discs; ascospores 1/ascus, about 100-300 x 50-100 Ám; Mediterranean-Atlantic, from Wales and Ireland to Greece; primary species of P. excludens --- 4/5/P. monogona Nyl.
13b Thallus with norstictic and picrolichenic acids, areolated, areoles 0.2-0.5 mm wide; fertile warts 1-1.8 mm wide, prominent, with 1-3 discs, soralia-like; disc black with white pruina; ascospores 1/ascus, 100-150 x 35-50 Ám, with strongly striate wall; on siliceous rock near Tanger, also in Spain (Boqueras 2000); primary species of P. teneriffensis --- P. ludovicae Werner

14a Thallus without isidia, sometimes with soralia, more or less grey, K- or K+ brownish; fatty acid iH; on sandstone in border area Saxony/Bohemia/Silesia --- 5/P. ocellata (Wallr.) Koerb.
14b Thallus without isidia and soralia, K- or K+ brownish; protocetraric acid; on siliceous stone in the Aegean, Greece --- 12/P. pseudoparotica Sipman
14c Thallus with coralloid isidia or with columnarly elongated warts --- 15

15a Thallus with dense, columnar, often fertile warts --- 16
15b
Thallus with scattered isidia or thallus warts --- 17

16a Thallus with numerous dense, columnar fertile warts occasionally apically bearing 2-5 discs, mostly apically bursting and producing soredia; fatty acids iH; Ireland --- P. polythecia (Tayl.) Erichsen
16b Thallus with numerous dense, 2-3 mm high and wide, columnar fertile warts apically bearing 2-4 black-brown discs, at first with greyish cover; ascospores 1/ascus, about 200 Ám long; Spain --- P. clementeana MŘll.Arg.

17a Isidia thin, about 0.1-0.3 mm thick, granular to coralloid, concolorous with thallus, pale greyish to whitish; thallus P+ yellow-orange, K+ yellow, C-, KC-, UV-; thamnolic acid; discs rare, usually in groups of 2-4 in 1.5-2 mm wide fertile warts; discs more or less brown; ascospores 2/ascus, about 80-140 x 40-80 Ám; widely distributed and often frequent on boulders and outcrops of non-calcareous rock, occasionally on bark, rather variable; syn. P. subdubia --- 1/2/4/5/P. corallina (L.) Arnold
17b Isidia thicker, like thallus warts --- 18

18a Thallus smoky grey, with mammose, about 1-1.5 mm wide, dense, more or less sorediate papillae; thallus P+ red, K+ yellowish to brownish; fumarprotocetraric with or without succinprotocetraric acids; discs rare, 1-2 together on the papillae, with blackish discs; ascospores 180-200 x 60-70 Ám; southern France to N. Africa; looks similar to the corticolous P. graeca (28c) --- 2/5/P. mammosa Harm.
18b Thallus without sorediate papillae, grey to smoky grey, with short-cylindrical, 0.4-1 mm wide isidia; thallus P+ red, K+ yellowish to brownish; fumarprotocetraric, tr. protocetraric acids; fertile warts more or less semiglobose, usually with 1-4 blackish discs; ascospores 1/ascus, of very variable size; on rock poor in lime, in the Carpathians, variable --- 5/P. stalactiza Nyl.
18c Thallus without isidia or soredia, pale grey, thick, coarse-wartily areolated; thallus warts basally constricted, to 3 mm high, with somewhat worn-off surface, centrally depressed; fumarprotocetraric, succinprotocetraric acids; apothecia immersed in warts, with black discs; spores unknown; central Italy --- 2/5/P. etrusca Erichsen

19a (10) Thallus, or at least soralia, K+ yellow turning red; norstictic acid present --- 20
19b
Thallus not K+ yellow turning red; norstictic acid absent --- 23

20a Spores 2/ascus; thallus without sorediate excrescences; apothecia with grey-pruinose discs; ascospores about 120-150 x 60 Ám; Greece --- 5/13/P. rhodiensis Erichsen
20b Spores 1/ascus; thallus with sorediate excrescences --- 21

21a Thallus yellowish white to brownish, with irregular, sorediate excrescences; apothecia immersed, with black discs; ascospores about 30-80 x 20-40 Ám; Finland --- 5/P. atropallida Vain.
21b Thallus grey, without or with regular sorediate excrescences --- 22

22a Thallus thin, long remaining endophloeodic, covered with numerous whitish-sorediate, 0.6-1 mm wide, convex warts, which partly bear a single blackish, white-pruinose disc; ascospores 200-300 x 50-100 Ám; France --- 5/P. monogoniza Nyl.
22b Thallus epiphloeodic, often granular-warty, thin, not rimose, more or less grey; fertile warts flat, almost of lecanorine appearance, usually with a single, widely open, black, usually pruinose disc; ascospores about 70-150 x 25-40 Ám; rare in humid sites in Bavaria --- 5/P. waghornei Hulting

23a Thallus (medulla) K+ yellow, P+ yellow to orange, thin, more or less endophloeodic, grey to whitish; thamnolic acid; fertile warts numerous, about 1 mm wide, with usually a single reddish disc; ascospores (1-)2/ascus, (38-)94(-160) x (18-)36(-58) Ám, often not well developed; rare in western and central Europe; syn. P. laevigata (Nyl.) Arnold --- 1/2/5/P. trachythallina Erichsen
23b Thallus K- or K+ indistinctly yellowish or brownish --- 24

24a Thallus C+ red; fertile warts of lecanorine appearance, with usually a single reddish disc --- see P. velata 44a
24b Thallus C- --- 25

25a Ascospores 2/ascus, about 100-150 Ám long; thallus whitish, rimose to radiate-plicate; thiophaninic acid, sometimes with confluentic and/or 2'-O-methylperlatolic acid; fertile warts to 1 mm wide, usually with several (-8) dark discs; thallus K and P almost -; Mediterranean --- 5/P. ilicicola Harm. --- 25
25b
Ascospores 1/ascus --- 26

26a Discs reddish; thallus P+ red or at least KC+ pink or violet, not orange --- 27
26b
Discs grey to black; thallus P-, KC- or KC+ orange --- 29

27a Medulla KC+ violet; thallus P- but soralia P+ orange-red to red; picrolichenic acid; fertile warts strongly convex, usually with a single brownish disc; ascospores about 220-350 Ám long; thallus usually without soralia; on deciduous trees in Central Europe, more common in the Mediterranean; status uncertain, seems distinct in Mediterranean but is usually synonymized elsewhere; syn. P. amara var. slesvicensis --- 2/P. slesvicensis Erichsen
27b Medulla KC+ pink; thallus P+ orange-red to red; picrolichenic acid absent --- 28

28a Thallus rather thick, shelf-like areolate, bluish grey; physodalic, tr. protocetraric acids; fertile warts white, usually with a single, reddish disc; ascospores about 90-200 Ám long; on smooth bark, often Fagus or Abies, in subatlantic parts of western Europe, extending to the Baltic Sea and the northern Alps; syn. P. leptospora Nitschke --- 1/2/4/5/P. multipuncta (Turner) Nyl.
28b Thallus rather thick, more or less rimose-areolated; fertile warts little emergent, with 1-5 small, (pale- to) dark brown discs; ascospores about 150-230 Ám long; thallus K+ reddish, P+ deep yellow, the warts P+ orange; atlantic part of Central Europe, rarely found; =P. multipuncta? --- 7/P. laureri Erichsen
28c Thallus whitish grey with strong, 0.5-1 mm wide papillae and apothecium-like, 1.5-3 mm wide fertile warts and - sorediate warts; discs usually several together, to 1.5 mm wide; ascospores about 160-280 x 50-80 Ám; fertile warts and medulla P+ red; fumarprotocetraric with + succinprotocetraric or protocetraric acids; several times found in Greece, Sardinia, Corsica; looks like corticolous form of P. mammosa --- 2/5/P. graeca Erichsen

29a Thallus KC-, UV-, fatty acids --- 30
29b Thallus KC-, UV-, no substances present; ascospores about 200 m long; thallus epiphloeodic, pale ashy grey, finely rimose-areolate; fertile warts about 1 mm wide, with a single blackish disc; Italy, Crete --- 1/5/P. cf. rhodiensis Erichsen
29c Thallus KC+ pink, UV-, fumarprotocetraric acid;  discs dark-brown or black, level to sunken, c. 0.4 (0.1-0.87) mm wide, usually single, initally white-pruinose, later pruinose-sorediate to sorediate; ascospores cylindric, (66-)134(-196) x (21-)46(-69) mu;  reported from Spain (Boqueras 2000) --- P. multipunctoides Dibben
29d Thallus KC+ orange, UV+ orange-red, thiophaninic with planaic or confluentic acids --- 32

30a Medulla J+ blue; thallus thin, at first endophloeodic, smooth to warty; thallus K, C and P-; fertile warts to over 1 mm wide with a single, deeply immersed, blackish disc; ascospores about 90-140 Ám long; so far only near Gdansk, on Betula; =P. ophthalmiza?? --- P. brachyspora Erichsen
30b Medulla J- --- 31

31a Thallus flat, not areolated, thin to rather thick, not sorediate; fertile warts more or less regularly distributed, flat, 0.5-1 mm wide, usually with 1-2, greyish pruinose to blackish, to 0.5 mm wide discs; ascospores about 130-200 x 50-70 Ám; 4 indet. fatty acids; on leached bark of e.g. Betula and Abies in oceanic and mediterranean areas, in particular in mountain forest --- 4/P. ophthalmiza (Nyl.) Nyl.
31b Thallus verrucose, not areolated, rather thick, sorediate; rarely fruiting, with scattered, about 1-4 mm wide fertile warts --- see P. albescens 141b

32a Thallus not sorediate; thiophaninic, planaic, 4-O-dimethylplanaic acids; fruits lecanorine with black disc more or less covered with thick, white pruina; epithecium greenish, K+ violet; ascospores 120-190 x (40-)60-75(-90) Ám; on Juniperus in continental Spain --- 9/10/P. paramerae Crespo & Vezda
32b Thallus more or less sorediate, brownish white, more or less rimose; thiophaninic, confluentic acids; hymenium 400-500 m high; fertile warts in dense groups, to about 1 mm wide, with blackish disc and swollen thalline margin; ascospores about 150-250 x 60-90 Ám; Greece --- 5/P. corinthiaca Erichsen
32c Thallus not sorediate, whitish, granular-warty-rimose; thiophaninic, 2'-O-methylperlatolic acids; fertile warts appressed, with a single blackish disc covered by white pruina composed of several apothecia; hymenium 250-300 Ám; ascospores about 180-220 x 75-100 Ám, with thick, smooth wall; Mediterranean --- 2/5/10/P. caesioalba (Flot.) Nyl.

33a (9) Ascospores (6-)8/ascus, usually under 50 Ám long --- 34
33b
Ascospores 4/ascus, about 30-60 x 25-35 Ám; discs blackish; paraphyses simple to little branched; thallus whitish, P-, with dense, almost semiglobose fertile warts; no substances; on soil or bark; syn. P. freyi Erichsen --- 5/Megaspora verrucosa (Ach.) Hafellner & V.Wirth
33c Ascospores 2/ascus --- 42
33d
Ascospores 1/ascus, usually over 100 m long --- 44

34a Isidia numerous, about 0.3-0.4 mm thick, 1-3 mm long, fragile, dark-tipped isidia; thallus K+ yellow becoming rusty red, P+ yellow becoming orange, C+ pink or C-, KC+ yellow-red; fumarprotocetraric, trace protocetraric or gyrophoric acids --- see P. oculata 152a
34b Isidia absent --- 35

35a On rock; thallus whitish to dark grey or brownish, P+ orange, K+ yellow to orange, C-, KC-, UV-; stictic, sometimes with tr. constictic and/or norstictic acids; fertile warts 0.5-1 mm wide, flattened, usually with several, rounded-edgy, often confluent, black, naked discs; ascospores about 20-40 x 10-25 Ám; on hard, non-calcareous rock, preferably serpentine, widely distributed but usually scattered; perhaps more species involved; syn. P. inquinata (Ach.) Th.Fr., P. aspicilioides Samp. --- 1/2/4/5/11/P. chiodectonoides Bagl.
35b On bark or wood --- 36

36a On wood or on bark; ascospores rounded; thallus endo- to epiphloeodic, thin, grey, with rounded, whitish, about 0.5 mm wide soralia; thallus P+ red, K+ dirty red, C-, KC+ pink to red; fumarprotocetraric, tr. protocetraric and/or gyrophoric acid; fertile warts to 1 mm wide, Lecanora-like, with blackish, wide, scabrid disc and swollen margin; epithecium olive-green, K+ violet; ascospores about 10-15 x 8-12 Ám; rare, on smooth barked trees, esp. Corylus, Sorbus, and on wood of Pinus and Betula, in Fennoscandia, Britain, Pyreneans --- 1/2/4/5/P. pupillaris (Nyl.) Th.Fr.
36b On bark; ascospores elliptic; thallus verrucose, yellowish, centrally with pulverulent-sorediate surface; K+ yellow turning red, C+ orange; thiophaninic and norstictic acids major; apothecia with dark brown disc and thick, pulverulent margin; epithecium brown, K+ violet; ascospores 4-5(-8)/ascus, biseriate, 50-70 x 25-35 Ám, with smooth walls; on Quercus suber in Morocco, also in Spain (Boqueras 2000) --- 10/P. praelutescens Werner
36c On bark; ascospores elliptic; thallus KC+ yellowish or red --- 37

37a Thallus thin, usually endophloeodic, whitish-greyish, UV-; no thiophaninic acid, with gyrophoric acid; fertile warts flat but with clearly raised margin, 0.4-0.7 mm wide, with single, flesh-brownish disc and irregular margin; on smooth bark, mainly of Alnus, Betula, in Scandinavia and the Alps --- (1/2/5/P. carneopallida) 38
37b
Thallus epiphloeodic, thickish, grey to strongly yellowish, UV+ orange, with thiophaninic and sometimes gyrophoric acid; Mediterranean and Atlantic --- 39
37c
Thallus epiphloeodic, thin becoming warty, continuous; no substances; fertile warts hemispherical with contracted based and slightly depressed tip, 1-1.4 mm wide; ostioles usually single, black, depressed, initially punctiform, later widened to 0.5 mm; ascospores biseriate, (39-)45-60 x (21-)28-39 Ám, smooth-walled; Cyprus; poorly-known taxon --- 5/P. cypriaca Erichsen
37d Thallus epiphloeodic, white to grey, irregularly warty, P+ red, KC+ red; fertile warts to 1 mm high; discs single, punctiform, later to 0.5 mm wide, blackish; ascospores 70-100 x 30-45 Ám; on Quercus in Tunisia; poorly-known taxon --- P. debazaci Werner

38a Ascospores about 20-30 x 12-16 Ám; Northern Europe, Scotland, Wales; --- syn. P. protuberans (Sommerf.) Th.Fr. --- P. carneopallida (Nyl.) Anzi v. cinereopallida
38b
Ascospores 28-42 x 15-24 Ám; Alps, Vosges, Iceland --- v. macrospora Erichsen

39a Discs blackish --- 40
39b
Discs yellowish to brownish --- 41

40a Thallus strongly yellow, rather thick; fertile warts rounded, clearly raised, about 1-1.5 mm wide, with single, to 1 mm wide, flat, black disc and swollen margin; ascospores about 70-100 x 30-50 Ám; on bark in the Mediterranean widespread (often included in P. hymenaea (41a))  --- 5/6/P. lecanorodes Erichsen
40b Disc blue-black, small; ascospores 50-60 x 20-35 Ám; N. Africa; = P. lecanorodes?; poorly-known species --- P. lapieana B. de Lesd.

41a Thallus yellowish to ash-grey, more rarely clearly yellow, thin to rather thick; fertile warts usually frequent, often deformed, to 2 mm wide, with 1-4 deformed-rounded discs; ascospores about 60-110 x 30-50 Ám; on bark of deciduous trees in well-illuminated sites in W. Europe to S. Scandinavia and the Bohemian Forest, and in the Mediterranean, absent from the Alps; syn. P. wulfenii DC --- 1/2/4/5/P. hymenea (Ach.) Schaer.
41b Thallus whitish grey, thin; K-, C-; fertile warts raised, 0.3-1.5 mm wide, lecanoroid with thick margin; disc initially round, 0.3 mm wide, later lecanoroid, pale brown; ascospores 8/ascus, 48-66 x 24-32 Ám; Rumania; = P. hymenea?; poorly-known species --- P. transsilvanica Ciurchea

42a (33) Discs pale; thallus almost always endophloeodic --- see P. heterochroa 52b
42b Discs blackish; thallus K+ yellow --- 43

43a Discs single, punctiform to deformed, surrounded by lacerate thalline margin; subatlantic --- see P. pustulata 54a
43b Discs single, regularly rounded, black, 0.4-0.8 mm wide together with narrow, smooth margin; thallus thin, smooth, whitish, occasionally sorediate (v. elatina Erichsen, on conifer bark in the Alps); no substances; ascospores about 60-120 x 30-55 Ám; Fennoscandia, rare in the Alps --- 1/2/5/P. stenhammari Hellb.
43c Discs single, punctiform to deformed, surrounded by smooth, slightly verrucose margin; thallus strongly yellow, thick, rimose-areolated or warted, not zoned at the margin; thiophaninic acid; fertile warts with constricted base, 1-1.2 mm wide, abundant and confluent, rounded, with initially punctiform, later to 0.5 mm wide, flat, smooth; epithecium K+ violet, C+ violet; ascospores 100-170 x 50-70 Ám; on Cedrus in Morocco; syn. P. ilicicola var. tazzekensis (INED.?) --- P. tazzekensis Werner

44a (33) On bark; thallus C+ red, white to greyish, smooth to rimose-verruculose, at the margin often radiate-plicate; fertile warts numerous but scattered, 0.5- over 1 mm wide, lecanora-like rounded, with strong, raised, sometimes finely sorediate margin and usually single, pale reddish disc; ascospores about 150-300 x 50-90 Ám; lecanoric acid, sometimes with lichexanthone; SW Europe, occasionally extending to the Baltic --- 1/2/4/5/P. velata (Turner) Nyl.
44b On rock --- 45

45a Thallus C+ pink or red, KC+ pink or red; lichexanthone, lecanoric acid; thallus whitish, thickish, more or less covered by semiglobose, more or less coarsely warty fertile warts; discs reddish, to 0.5 mm wide; ascospores about 200-270 x 70-85 Ám; France, collected once, unusual form of P. velata?; acc. to Boqueras (2000) in Spain --- 2/5/P. conglobata (Ach.) Th. Fr.
45b Thallus C-; arctic species with pruinose discs on more or less calcareous substrate --- 46

46a Thallus J+ clearly blue, thin, whitish-greyish, areolate, with 1-1.5 mm wide, raised fertile warts bearing 1-2 blackish, 0.3-0.5 mm wide discs; ascospores about 135-240 x 40-90 Ám; protocetraric acid; Nowaja Semlja; = P. cribellata Branth? --- 5/P. solitaria H.Magn. (non Darb.) NOM. ILLEG.
46b Thallus J- or medulla weakly J+ violet; thallus chalky-whitish, at border almost lobed, rather thick; fertile warts in the centre dense, with 1-3 black, more or less white-pruinose, rounded-deformed discs and thick margin; ascospores about 140 x 50 Ám; no substances; Lapland, on limestone --- 1/5/P. tornensis H.Magn.

47a (8) Fertile warts strongly widened at base, not sharply delimited from the thallus, usually flat; soralia absent; thallus K- to K+ pale yellow, rarely more strongly yellow, sometimes endophloeiodic; on bark --- 48
47b
Fertile warts sharply delimited, usually distinctly contracted at base or areole-like; thallus K-, K+ yellow or K+ yellow turning red, always epiphloeodic when on bark; on soil, bark or rock --- 55

48a Ascospores 8/ascus --- 49
48b
Ascospores usually 4-5(2-8)/ascus; thallus thin, at least initially endophloeodic, whitish to greenish grey; coronaton, usually with stictic, norstictic acids, indet. depsids; fertile warts 1-2 mm wide, slightly convex-flattened, often dense, basally constricted or nodulose, usually with 1- few ostioles; ostioles usually greyish or brownish to blackish, but sometimes widened, flesh-coloured, with pale to brownish epithecium; ascospores about 70-100 x 25-40 Ám; on smooth bark of forest trees, mainly Fagus, widespread in the deciduous forest zone, variable, often with the hymenia eaten away; syn. P. leioplaca (Ach.) DC. --- 1/3/4/10/P. leucostoma (Bernh.) A.Massal.
48c Ascospores 2/ascus --- 51

49a Thallus endophloeodic to weakly epiphloeodic; stictic acid present; in N Europe, the Alps, Carpathians, Vosges --- 49'
49b Thallus clearly epiphloeodic; stictic acid absent (unknown in 50b); in southern Europe --- 50

49'a Epithecium blackish, K+ violet like dark marginal rim; ascospores about 20-40 x 12-20 Ám; thallus thin, endophloeodic, whitish-greyish; coronaton, stictic sometimes with tr. norstictic and/or constictic acids, sometimes subst. mH; fertile warts to 1 mm wide, at base widened to contracted, usually with 1-5 ostioles; on bark and wood of deciduous trees and Juniperus, mainly near the soil, in N Europe, the Alps, Carpathians, Vosges --- 1/2/5/P. sommerfeltii Flörke
49'b Epithecium almost colourless to brownish; ascospores about 30-70 x 20-30 Ám with weakly punctuated wall; thallus thin, endophloeodic to weakly epiphloeodic, more or less grey-greenish; coronaton, stictic, tr. norstictic, constictic acids; fertile warts to 2.6 mm wide, with 1-3(-8) pale ostioles; on smooth bark of young trees, e.g. Alnus, in N Europe and at lower elevations in the Central European mountains till Dalmatia; syn. P. leioplaca v. octospora Nyl. --- 1/2/5/10/P. alpina Hepp

50a Ascospores about 50-60 x 25-30 Ám, (4-)8/ ascus, with smooth walls; 1-2 pale. punctiform ostioles/wart; coronaton, 2'-O-methylperlatolic, confluentic acids; in Caloplacetum pollinii in Spain; also in Greece --- 3/10/P. sp. 1 (Giralt 1996) = P. werneriana Boqueras
50b Ascospores 90-95 x 33-36 Ám; thallus thin, smooth, greyish white, K+ yellowish, C-, KC+ yellowish; fertile warts depressed-subglobose, not constricted at base, 0.7-0.7 mm wide; ostioles mostly single, brown-black, immersed, 0.2-0.3 mm wide; on Erica on Teneriffe --- P. teguestensis Erichsen
50c See also P. cypriaca Erichs. 37c, P. debazaci R. G. Werner 37d, and P. lapieana Bouly de Lesd. 40b, poorly-known Mediterranean corticolous taxa.

51a Ostioles pale to pinkish --- 52
51b
Ostioles blackish --- 53

52a Thallus thin, UV+ orange; fertile warts rounded to irregular, rimose, flat; artothelin, granulosin, gyrophoric, lecanoric acid; ostioles 1-3/wart, flat, 0.3-0.4 mm wide, pale, C+ pinkish red; ascospores 80-110 x 28-50 Ám, with transversally striate walls; Portugal, Baleares Isl. --- 5/10/P. dispar J.Steiner
52b As a, ostioles C-; thiophaninic, stictic, and traces of norstictic, constictic acids, 0-methylmonochlorlichexanthone; ostioles with colourless epithecium, to 0.5 mm wide, usually single or with few together, in to 1.5 mm wide fertile warts; ascospores about (50-)70-110(-170) x 25-60 Ám with transversely striated walls; on bark in the Mediterranean; syn. P. maximiliana Klem. --- 2/3/5/10/P. heterochroa (MŘll.Arg.) Erichsen

53a Fertile warts slightly convex, at base widened to clearly delimited; ascospores about 100-220 x 40-75 Ám, with slightly plicate walls; mainly on Fagus and Carpinus in Central Europe widespread but infrequent; syn. P. leioterella Erichsen, P. communis v. leiotera Nyl., P. colliculosa Körb. --- see P. pertusa 79b
53b Fertile warts slightly convex, at base scarcely widened, c. 0.5 mm wide; coronaton, tr. confuentic, 2'-O-methylperlatolic acids; ostioles usually single, pruinose; epithecium granulose-greyish; ascospores 65-95 x 25-27 Ám; on Quercus in Israel --- 5/P. carmelii Reichert & Galun
53c Fertile warts flat, regularly becoming apothecium-like with widened discs --- 54

54a Discs remaining punctiform or soon deformed, with whitish, irregular, about 0.5 mm wide margin, 1-8/wart; thallus thin, grey-greenish; epithecium blackish, K+ red-violet; ascospores about 60-130 x 20-40 Ám, wall finely striate; thallus KC+ yellow to yellow-reddish; stictic acid, 2-chloro-6-O-methylnorlichexanthone, sometimes with (traces of) constictic, norstictic acids; on smooth bark of young deciduous trees, especially Fagus, Mediterranean-Atlantic till western Central Europe (syn. P. exalbescens Nyl.) --- 2/3/5/10/P. pustulata (Ach.) Dufour
54b Discs remaining punctiform, 1/wart; thallus thin, grey, often with yellowish tinge; epithecium dark green or blackish, K-; ascospores 70-95 x 25-35 mu, wall transversely striate; thallus KC+ orange-red; thiophaninic and norstictic acids; on smooth bark, Spain --- 10/P. luteola Boqueras

55a (47) Thallus K+ yellow->fast red (norstictic acid) --- 56
55b
Thallus K+ yellow (usually stictic or thamnolic acid) --- 61
55c
Thallus K- (no norstictic, stictic, thamnolic acid) --- 81

56a On bark and wood --- 57
56b
On rock --- 58

57a Thallus with irregular, sorediate outbursts, without isidia, rimose-warted, whitish; thallus P+ strongly yellow; fertile warts scarce, always cushion-like accumulated, with depressed ostiole; ascospores 1-2/ascus, 110-195 x 34-55 Ám; particularly on Fagus, Yugoslavia --- 8/P. servitiana Erichsen
57b Thallus isidiate, more or less grey, often grey-greenish; isidia granular to elongate-coralloid, about 0.1-0.4 mm thick, often in cushion-like accumulations, in places becoming sorediate; fertile warts rare, usually cushion-like accumulated; ascospores (1-)2(-4)/ascus, about 100-200 x 30-60 Ám; thallus P+ yellow, sorediate spots P+ orange; norstictic acid; on bark of old, free-standing trees in deciduous forest zone of W and Central Europe, widespread and common, very variable; syn. P. phymatodes (Ach.) Nyl., form of shady places with longer isidia; P. polycarpiza Choisy et Werner --- 1/2/4/5/P. coccodes (Ach.) Nyl.

58a Isidia absent --- 59
58b
Isidia present, granular to coralloid --- 60

59a Thallus deeply rimose-areolate, rather thick, brownish white; isidia absent; thallus C-, P-; norstictic acid; fruit-bearing areoles to over 3 mm wide, smooth, with many congested, to about 1 mm thick, each with 1-8, blackish ostioles; ascospores 2/ascus, about 150-250 Ám long, often poorly developed; on non-calcareous rock, e.g., serpentine, Mediterranean-Atlantic --- 2/5/P. apennina Bagl.
59b Thallus yellowish, rather thick, UV+ orange, K+ yellow turning red, KC+ orange, P+ range, warty-rimose, cartilaginous; thiophaninic and norstictic acid major; fertile warts 1-2 mm wide, semiglobose, with more or less depressed tip containing usually several black, non-pruinose ostioles; ascospores 8/ascus, 85-110 x 40-65 Ám, thick-walled; on sandstone on the Baleares (type only); close to P. rupicola but with different chemistry --- P. huneckiana Feige & Lumbsch

60a Isidia cushion-like, greyish to pale brownish, without dark tip; occasionally on rock (when isidia finely granular, 0.1-0.4 mm wide; thallus with plenty punctiform sorediate outbursts; on granite in N Germany: v. petraea Erichsen) --- see P. coccodes 57b
60b Isidia with thickened, blackish tip, scattered, fragile and leaving crater-like scars, 0.5-1 mm thick, usually short granular, more rarely elongated; thallus rimose-areolated, brownish grey; areoles about 1-3 mm wide, warty to nodulose; medulla P+ orange, K+ yellow-red, KC+ yellow-red, C-, UV-; norstictic acid; apothecia rare, with 2-7 punctiform, grey-black ostioles in 1-3 mm wide, more or less dense, semiglobose fertile warts; ascospores 2/ascus, about 125-200 x 50-80 Ám; on non-calcareous rock from Scandinavia through Central and Western Europe to the Mediterranean, very scattered; syn. P. ceuthocarpoides Zahlbr., P. microsticta (Sm.) Erichsen, P. concreta Nyl. --- 1/4/5/P. pseudocorallina (Sw.) Arnold

61a (55) Isidia present; thallus often sterile --- 62
61b
Isidia absent; thallus usually fertile --- 65

62a On rock --- 63
62b
On bark --- 64

63a Thallus grey, KC- or + pale yellowish; medulla J-; thallus always fertile, thickish, rimose-areolated, with usually numerous, small, 0.2-0.5 mm high and 0.2 mm wide isidia; coronaton, stictic (+ tr. norstictic, constictic) acids; fertile warts semiglobose, isidiate, with 1-6 ostioles; ascospores 2/ascus, about 170-230 x 60-80 Ám; Western Europe, occasionally to Saxony; syn. P. chionea; = P. pertusa? --- 2/5/7/P. areolata (Ach.) A.Massal.
63b Thallus yellowish, KC+ orange, UV+ orange, with usually scattered, elongated, to 2 mm long and 0.3-0.5 mm wide, usually simple papillae; preferably on steep rock faces in Mediterranean; for further details see P. rupicola (68a) --- 2/P. rupicola (Fr.) Harm. v. coralloidea (Anzi) Croz.

64a Thallus P+ ochraceous, K+ orange, greyish green to pale- or yellowish grey, more or less densely covered by granular to elongate and coralloid, about 0.05 mm thick isidia, additionally with sorediate outbursts; coronaton, stictic sometimes with tr. norstictic and/or constictic acids; fertile warts semiglobose, more or less isidiate, usually in groups, with usually 1-4 ostioles; ascospores usually 4/ascus, about 90-160 x 45-70 Ám; on bark mainly of broad-leaved, wayside trees, in temperate Europe widespread but scattered, rarely fruiting; syn. P. isidiifera Erichsen, shade form with elongate isidia --- 1/2/4/5/P. coronata (Ach.) Th.Fr.
64b Thallus P+ yellow, K+ yellow, more or less greyish, with scattered, button-like, to 0.1 mm thick isidia; thamnolic acid; species rarely on bark in southern Central Europe --- 7/see P. corallina 17a

65a (61) On rock --- 66
65b
On bark --- 72

66a Thallus composed of scattered, small, semiglobose warts, brownish grey to pale reddish, P-; indet. substances; sterile; Tatra; uncertain taxon probably no Pertusaria --- 5/P. scepusiensis (Gyeln.) Erichsen
66b Thallus continuous --- 67

67a Ascospores 8/ascus --- 68
67b
Ascospores 2/ascus --- 69

68a Thallus yellowish, UV+ orange, K+ orange-yellow, KC+ orange, P+ ochraceous, warty-rimose, cartilaginous; thiophaninic, stictic acid, sometimes trace norstictic; fertile warts to 2 mm wide, semiglobose, with more or less depressed tip containing usually several ostioles; epithecium K+ red violet and C+ red violet; ascospores about 70-100 x 30-50 Ám, thick-walled; on silicate in Mediterranean widespread, extending into the southern Alps and England; cf. P. huneckiana with norstictic instead of stictic acid. --- 2/5/P. rupicola (Fr.) Harm.
68b Thallus grey, dusty; fertile warts small, 0.5-0.7 mm wide, densely covering the thallus, semiglobose, usually with 3-6, often deformed ostioles which may fuse into discs; stictic acid; ascospores about 25-45 x 15-25 Ám; on granite in Silesia; syn. P. polycarpa Eitner --- 5/P. eitneriana Erichsen

69a Thallus yellowish, KC+ orange, UV+ deep orange-red, rimose-areolate; thiophaninic, stictic acids major; fertile warts slightly enlarged but scarcely thicker than sterile areoles, with several flesh-coloured (P. gallica?) or dark ostioles; ascospores about 75-140 x 35-60 Ám, with transverse striation; on non-calcareous rock in western Europe; syn. P. gallica B. de Lesd. --- 5/8/P. pluripuncta Nyl.
69b Thallus whitish grey, KC-; coronaton, stictic acid (as far as known) --- 70

70a Fertile warts applanate; thallus grey; sterile areoles till 1-1.5 mm wide; fertile areoles to 2.5 mm wide, with 1-2(-4) apothecia, often congested in nodulose groups; coronaton, stictic acid; ascospores about 100-170 x 30-60 Ám; northern Ural --- 5/P. globulata Oxner & A.M.Volkova
70b Fertile warts semiglobose; thallus yellowish --- 71

71a Medulla J-; thallus more or less grey, cartilaginous, usually more or less rimose-areolate; thallus K+ yellow, KC+ yellow, P+ orange-reddish; coronaton, stictic acid and accessories; fertile warts scattered to dense, about 1-1.5 mm wide, with 1 to few, punctiform ostioles; ascospores about 180-230 x 70-85 Ám; on non-calcareous rock throughout Europe, scattered; syn.: P. pallidoflava Erichsen; probably saxicolous form of P. pertusa --- P. rupestris (DC.) Schaer.
71b Medulla J+ blue; like P. rupestris; fertile warts to 2 mm wide, with 1-5 ostioles; ascospores about 170-215 x 58-80 Ám; on granite in Corsica; = P. rupestris? --- 8/P. subrupestris Zschacke

72a (65) Ascospores 8/ascus --- 73
72b
Ascospores c. 4/ascus --- 78
72c
Ascospores 2/ascus --- 79
72d
Ascospores 1/ascus, with pitted walls, 130-250 x 60-70 Ám; thallus whitish, thin, with scattered to dense, basally strongly constricted, to 0.7 mm wide fertile warts with 1-7 ostioles; thallus K+ pale yellowish, C-, P-; ascospores J+ violet; on Salix in Norway --- 1/P. porospora Norm.

73a Fertile warts with swollen margin surrounding one or several depressed, widened, confluent ostioles; Mediterranean-oceanic --- 74
73b
Fertile warts with not-depressed tip; ostioles persistently punctiform --- 75

74a Thallus yellowish grey to grey or strongly yellow, C-, P-, usually largely covered by numerous, to 2 mm wide, often deformed-plicate fertile warts containing usually 1-4 ostioles; ascospores usually 8/ascus, about 60-110 x 30-50 Ám; on smooth bark in Mediterranean and Atlantic Europe, northward till S. Finland, lacking in the Alps; syn. P. wulfenii DC., P. sublecanorodes Werner --- P. hymenea (Ach.) Schaer.
74b Thallus yellowish white, C+ yellow, P+ blue-grey, long endophloeiodic, later powdery, warty; fertile warts semiglobose, to 2 mm wide; ascospores about 90-120 x 40-55 Ám; thiophaninic, sometimes with gyrophoric acids; Dalmatia, S. France --- 5/P. cyparissi Körb.

75a Thallus C-; coronaton present --- 76
75b
Thallus C+ orange; thiophaninic acid present --- 77

76a Thallus grey, epiphloeodic, smooth to rugulose; fertile warts numerous, usually scattered, semiglobose, to 2 mm wide, at base distinctly constricted, usually with 3-6 ostioles; ascospores mostly 8/ascus, about 30-60 x 15-30 Ám; thallus K+ yellowish to brownish, C-, P-; coronaton, stictic (+ tr. norstictic) acids; mountain forest of alpide mountains and southern Europe --- 2/5/P. constricta Erichsen
76b Thallus whitish, long endophloeodic; fertile warts to 1 mm wide, usually with single apothecium, with more or less widely blackened tip; ascospores 25-40 x 15-20 Ám; thallus K+ pale yellow, C-, P-; on bark and wood usually of conifers in N Europe and the Alps. --- P. sommerfeltii Flörke v. melanostoma (Wahlenb.) Th.Fr.
See also P. alpina (49'b)

77a Thallus yellowish, epiphloeodic, smooth to rugulose; fertile warts numerous, usually scattered, semiglobose, 0.5-1(-1.5) mm wide, at base hardly constricted, with a single, yellowish to yellow, indistinct ostiole; ascospores 6-8/ascus, about 50-70 x 30 mu, irregularly uniseriate, ellipsoid, smooth-walled; thallus K+ yellowish, C-; thiophaninic, stictic acids major; Morocco --- P. leioplacella Nyl.
77b Thallus yellowish, epiphloeodic, smooth to rugulose; fertile warts numerous, usually scattered, semiglobose, smaller than in P. leioplacella, at base hardly constricted, with a single(-2), yellowish to yellow, indistinct ostiole; ascospores 6-8/ascus, about 30-70 x 20-30 Ám, uni- or biseriate, ellipsoid, smooth-walled; thallus K+ yellowish, C-; thiophaninic acid alone; SW France, Spain (Boqueras 2000) --- 5/P. plombii B. de Lesd.

78a (72) Thallus thin, brownish, with very small, nodose, about 0.4 mm wide, dense fertile warts with to 6 ostioles; ascospores 1-6/ascus, about 60-90 x 30-40 Ám; thallus K+ yellowish, C-, P-; coronaton, stictic (+ tr. norstictic, constictic) acids; on Carpinus in Silesia --- 5/P. caesioumbrina Eitner
78b Thallus grey, with larger fertile warts; ascospores usually 4/ascus --- see P. leucostoma 48b

79a (72) Thallus more or less yellowish-greyish, long endophloeodic, thin; thiophaninic, stictic, sometimes traces norstictic, constictic acids; fertile warts flattened, basally distinctly constricted, about 1-1.5 mm wide, with usually 1-4, ochraceous, waxy ostioles; ascospores about 100-145 x 40-60 Ám, with smooth wall; on deciduous trees in the Mediterranean, very rare: Dalmatia, Portugal, Azores --- 5/P. ficorum Zahlbr.
79b When spores 2/ascus and striate, see see P. heterochroa 52b
79c Thallus greyish, verruculose to rimose; fertile warts scattered to dense, to about 2 mm wide, semiglobose, basally more or less strongly constricted, of irregular shape, with usually several to many ostioles; ascospores about 145-230 x 40-80 Ám, with zoned or grooved wall; thallus P+ orange-red, K+ yellow, C-, KC+ yellow, UV+ pale orange; coronaton, stictic acid, sometimes norstictic, constictic acids, subst. mH; on bark mainly of deciduous trees, in central Europe very widespread and polymorphic, in the Alps up to the subalpine zone. --- (P. pertusa) 80

80a Thallus whitish to yellow-whitish; fertile warts low and wide with many conspicuous, blackish ostioles; Mediterranean; syn. P. gattefossei Choisy on limestone in Morocco?; syn. P. oleae Zschacke from Corsica? (medulla J+ blue; epithecium K+ violet) --- 1/2/5/P. pertusa (L.) Tuck. v. meridionalis Zahlbr.
80b Thallus more or less grey; fertile warts with usually less ostioles; widespread; syn. P. chioneoides Erichsen --- v. pertusa

81a (55) Thallus C- --- 82
81b
Thallus C+ red --- 89

82a On rock --- 83
82b
On bark --- 85

83a Thallus thin, whitish to dirty reddish, without papillae but with punctiform, to 0.3 mm wide soralia; alectoronic acid, indet. substances; fertile warts scarce, rounded, about 1-2.5 mm wide, to 0.8 mm high with usually many pale reddish, finally slightly widened ostioles; ascospores 8/ascus, about 30-50 x 15-35 Ám, thin-walled; on steep faces in Finmark --- Ochrolechia rhodoleuca (Th.Fr.) Brodo
83b Thallus papillate-isidiate --- 84

84a Medulla KC+ violet, with bitter taste; thallus grey, densely covered by simple to branched, to about 5 mm high, 0.5-1 mm thick papillae; fertile warts stalked like papillae, finally irregularly nodular, to about 3.5 mm wide, with usually several, finally widened ostioles confluent in a disc; ascospores 1/ascus, about 180-300 x 70-100 Ám; medulla and ostioles P+ red, KC+ violet; picrolichenic and protocetraric acids; SW Europe, Wales, W Norway; probably heterogeneous --- 1/2/4/5/P. melanochlora (DC.) Nyl.
84b Medulla KC- or + pale yellow, without bitter taste, J+ reddish; papillae usually not branched; thallus always sterile, rimose-areolate, with scattered, strong, short-cylindrical, to 1.5 mm high and about 0.5 mm wide papillae; fatty lH; on acid silicates in the central Alps and Black Forest; syn. P. isidioides (Schaer.) Arnold --- 2/5/P. schaereri Hafellner

85a Thallus more or less endophloeodic, whitish --- 86
85b
Thallus clearly epiphloeodic --- 87

86a Ostioles pale to yellowish, deeply impressed; fertile warts about 0.6-0.8 mm wide, semiglobose, basally strongly constricted, with single ostioles; asci ventricose-bacillar; ascospores 4-?/ascus, about 50-70 x 20-40 Ám; on Alnus in Finland --- P. poriniza Nyl.
86b Ostioles black; coronaton, stictic acid; fertile warts to 1 mm wide, at base widened to contracted, usually with 1-4 ostioles; ascospores 8/ascus, about 20-40 x 12-20 Ám --- see P. sommerfeltii 49'a

87a Fertile warts with yellowish tip, on whitish thallus, to 1.5 mm wide, flattened semiglobose, basally strongly constricted; alectoronic (sometimes absent?), lichesterinic acids; ostioles yellowish-brownish; ostioles usually in groups of 1-3; ascospores 4/ascus, about 50-80 x 30-40 Ám; on bark mainly of Juniperus twigs and on rock outcrops, in subarctic northern Fennoskandia, Iceland, Faroes, Scotland, Alps?; syn. Ochrolechia xanthostoma (Sommerf.) K.Schmitz & Lumbsch --- 1/4/5/P. xanthostoma (Sommerf.) Fr.
87b Fertile wart tips concolorous with thallus; ostioles blackish; thallus grey, strong; in deciduous forest zone --- 88

88a Ascospores 2/ascus --- see P. pertusa 79b and P. carmeli 53b
88b Ascospores 4/ascus --- see P. leioplaca 48b
88c Ascospores 6/ascus, about 60-90 x 30-40 Ám; thallus grey; fertile warts scattered, basally strongly constricted, with 1-several ostioles; coronaton, sometimes with stictic (+ tr. norstictic) acid; on Populus in Finland --- 5/P. raesaenenii Erichsen
88d Ascospores 8/ascus --- see P. hymenea 74a, P. cypriaca 37c, P. debazaci 37d, P. werneriana 50a, P. teguestensis 50b and P. plombii 77b

89a (81) On bark --- see Ochrolechia subviridis 99b
89b On rock --- see P. kasandjefii 100a

90a (2) Medulla and, if present, soralia C+ pink or red and/or KC+ pink, red or violet-red --- 91
90b
Medulla and, if present, soralia C-, KC- or C and/or KC+ yellow to orange, not pink-red --- 109

91a Medulla and, if present, soralia C+ pale red to red, KC+ red, P- or P+ yellowish; thallus without bitter taste (gyrophoric or lecanoric acid usually present) --- 92
91b
Medulla and, if present, soralia C-, KC+ violet-red, P- or P+ orange to red; thallus with bitter taste (picrolichenic or (fumar)protocetraric acid present) --- 101

92a Thallus sorediate; on rock or bark --- 93
92b
Thallus not sorediate; on rock --- 100

93a On rock --- 94
93b
On bark --- 95

94a Thallus rimose-areolated, almost smooth, rather thick, at border radiate-rugulose, the areoles about 0.3-0.8 mm wide; lecanoric, variolaric acids; soralia rounded, coarse-grained; fertile warts usually with single, brownish disc, initially white-pruinose; ascospores 1/ascus, about 180-240 x 60-100 Ám; on non-calcareous or weakly calcareous rock, scattered throughout Europe, locally frequent; syn.: Ochrolechia lactea (L.) Hafellner & Matzer --- 1/2/4/5/Pertusaria lactea (L.) Arnold
94b Thallus rather thick, not rimose but swollen-warty, between the warts coarsely sorediate; gyrophoric acid; S France; syn. P. tumidula Erichsen --- Ochrolechia crozalsiana Clauz. & Vezda

95a Thallus with delimited, rounded soralia, whitish grey to pale grey --- 96
95b
Thallus without rounded soralia --- 99

96a Thallus densely coarse-warty, not radially rugulose; soralia mostly on the tip of basally constricted warts; gyrophoric and variolaric acid; disc dark, pruinose; Yugoslavia, S. France, Spain; syn. Pertusaria dalmatica Erichsen --- 2/5/14/O. dalmatica (Erichsen) Boqueras
96b Thallus not coarse-warty; soralia appressed --- 97

97a Thallus with distinct, zoned, silverish-white, radially rugulose border, in the center not areolated, with 1-1.5 mm wide, more or less strongly convex soralia; cortex K-; lecanoric acid dominant, with or without variolaric acid; on bark of deciduous trees in light forest or free-standing, widespread in central Europe but common only in suboceanic areas --- 1/2/4/5/P. hemisphaerica (Flörke) Erichsen
97b Thallus without distinct, zoned border; gyrophoric acid dominant substance, usually with a trace of lecanoric acid --- 98

98a Thallus UV+ yellow, not cartilagineous; lichexanthone, gyrophoric acid; soralia about 0.5-1 mm wide; cortex K+ yellowish; East Central Europe, Eastern Europe; syn. P. arborea Krey, P. myriosora Erichs. --- 5/Ochrolechia arborea (Krey) Almb.
98b Thallus UV- or + whitish, thin or rather thick, cartilaginous, pale brownish grey, hardly fissured, irregularly warted; gyrophoric, variolaric, tr. lecanoric acids; soralia dense, rounded, usually flat, or somewhat concave, farinose, whitish, 0.4-0.8 mm wide, sometimes confluent; fertile warts rare, scattered, subhemispherical with constricted base, with slightly depressed tip, white-sorediose, 0.8-1.2 mm wide; ostiole single, initially punctiform, later to 0.6 mm wide, flesh-coloured; ascospores unknown; on Pinus in Cyprus; probably belonging to Ochrolechia --- 5/P. pityreocarpa Erichsen
98c Thallus UV- or + whitish, thin or rather thick, cartilaginous, whitish grey, hardly fissured, irregularly warted; gyrophoric, tr. lecanoric acids; soralia dense, rounded, usually flat, or somewhat concave, farinose to granulose, whitish, 0.4-0.8 mm wide, sometimes confluent; fertile warts rare, scattered, subhemispherical with constricted base, with slightly depressed tip, white-sorediose, 0.8-1.2 mm wide; disc to 0.6 mm wide, flesh-coloured; widespread, common and variable --- 5/O. androgyna (Hoffm.) Arnold

99a (95) Thallus rather thick, finely warty, uneven, more or less dirty grey, with initially punctiform, later confluent soralia; C+ reddish; gyrophoric, tr. lecanoric acids; on bark of roadside trees, in northern Central Europe and southern Sweden, probably not widely distributed; syn. P. sordidogrisea Erichs. --- 5/Ochrolechia sordidogrisea (Erichsen) Schreiner & Hafellner
99b Thallus thin, grey to greenish grey, largely fine-grainedly isidiate to sorediate; on bark in suboceanic Europe; syn. P. inaequalis Erichs. --- Ochrolechia subviridis (H°eg) Erichsen

100a (92) Thallus whitish rimose-areolated; thallus warts 0.7-1.4 mm wide; lecanoric, variolaric acids; on volcanic rock in Bulgaria (perhaps in Ochrolechia?) --- 5/P. kasandjeffii Szatala
100b Thallus pale grey, not rimose-areolated; thallus warts 0.5-0.7 mm wide or confluent; gyrophoric, tr. lecanoric acids; on lava on Jan Mayen (perhaps in Ochrolechia?) --- 5/P. lavicola Erichs.

101a (91) Thallus with strong papillae or isidia, not sorediate, regularly fruiting --- 102
101b
Thallus without distinct papillae, sorediate, rarely fruiting --- 103

102a On rock in western Europe --- see P. melanochlora 84a
102b On bark in N and Central Europe, Mediterranean --- see P. slesvicensis 27a

103a On rock (see also 118) --- 104
103b
On bark --- 105

104a Soralia numerous, high-vaulted, dense, about 1-2 mm wide, almost covering the rimose-folded, very bitter thallus, not confluent; picrolichenic acid, sometimes with protocetraric acid; mainly on sandstone in central Europe; syn.? 5/P. caucasica Erichs. --- P. amara var. flotowiana (Flörke) Erichsen
104b
As P. amara, but with picrolichenic and norstictic acids; thallus K+ yellow turning red; Spain and Canary Islands --- 5/P. teneriffensis Vain.

105a Thallus with coarse, to 4 mm wide, sorediate warts, which develop into soralia with lacerate-sorediate thalline margin; soralium discs KC+ pale reddish, P+ orange-red; picrolichenic, protocetraric acids; on bark in Yugoslavia; syn. P. amara var. szatalai (Erichsen) Clauzade & Cl.Roux --- 5/P. szatalai Erichsen
105b Sorediate warts smaller --- 106

106a Thallus thin, whitish, with irregular to irregularly rounded, flat to concave soralia; thallus strongly bitter, KC+ pale yellow becoming pale brownish red; Eastern Prussia, on Tilia --- P. pseudophlyctis Erichsen
106b Thallus rather thick, more or less densely covered with rounded to punctiform soralia, grey, soralia white; soralia KC+ violet-reddish, P+ red; apothecia very rare, in soralium-like fertile warts; ascospores 1/ascus, about 140-230 x 50-70 Ám; picrolichenic +/- protocetraric acids; on bark of various deciduous and conifer trees throughout Europe, except the Arctic and the alpine zone --- (P. amara) 107

107a Picrolichenic acid present, fumarprotocetraric acid absent, protocetraric acid sometimes present; thallus usually P- --- 108
107b
Picrolichenic acid absent, fumarprotocetraric acid present, with traces of protocetraric and succinprotocetraric acids; thallus P+ orange-red (if thallus largely hypophloeiodic and succinprotocetarric acid absent, see 36a P. pupillaris) Soralia mostly delimited and rounded, convex or rarely excavate, up to 1.5(-3) mm wide, occasionally fused; thallus grey, rather thin, continuous; soredia coarse, more or less fused; apothecia rare, developing in the soralia, disciform, monocarpic, with pale pink disc to 0.7 mm diam.; spores 6/ascus, 18-20 x 10-14 Ám; on old Pinus in Scotland, more widespread on smooth, acid bark in Scandinavia --- 4/P. borealis Erichsen

108a Soralia about 2 mm wide, rounded, usually convex to globose, at age often concave; the common taxon --- 1/2/3/5/P. amara (Ach.) Nyl. v. amara
108b
Soralia punctiform, small, on the tips of fine papillae or warts, densely covering the thallus except the outer border; mainly on roadside trees, in central Europe not rare; syn. P. pulvinata Erichsen --- 2/v. pulvinata (Erichsen) Almb.

109a (90) Cortex and/or mark K+ yellow turning red (norstictic acid) --- 110
109b
Thallus not K+ red (no norstictic acid) --- 117

110a On bark --- 111
110b
On rock --- 112

111a Thallus greyish, with granular to cylindrical isidia and often also with sorediate outbursts --- see P. coccodes 57b
111b Thallus whitish, without isidia --- see P. servitiana 57a

112a Thallus not areolated, dark grey to olive-greenish, hardly rimose, with numerous irregular, rounded, 0.2-0.3 mm wide, grey-whitish to greenish soralia; Holstein; = P. excludens? --- 5/7/P. inopinata Erichsen
112b Thallus rimose-areolated, whitish grey, turning brownish in the herbarium --- 113

113a Thallus with scattered, granular to cylindrical isidia, additionally often with soralia --- see P. coccodes 57b
113b Thallus without isidia --- 114

114a Soralia remaining rounded and becoming convex --- 115
114b
Soralia spreading over the areoles and remaining flat, more or less confluent --- 116

115a Thallus rimose-areolated, greyish white to bluish grey, with numerous, rounded, 0.5-1-1.8 mm wide, slightly paler soralia, K+ yellow becoming red, KC+ yellow becoming orange, P+ orange-red in medulla and soralia, UV+ grey to yellowish; norstictic acid, with (?) or without salazinic, fatty acids, xanthone; SW Europe till Black Forest (see also Coccotrema citrescens, with diffuse cephalodia; stictic acid; close to soil; coastal Scotland, N. Ireland) --- 1/2/5/P. excludens Nyl.
115b Thallus rimose-areolated, whitish; areoles convex to wart-like with constricted base, becoming sorediate at the tips; norstictic and protocetraric acid; ascospores 2/ascus, about 80-150 x 50-80 Ám; calcareous rock, Algeria --- 5/P. fdoulesiana Harm.

116a Soralia usually flat remaining discrete and well-crowded, often becoming confluent or becoming slightly convex, usually delimited, (0.2-)0.3-0.7(-0.8) mm diam.; soralia greyish, pigment K+ violet (thalloidima green) --- see P. lactescens 7b
116b Soralia usually diffuse and becoming confluent or becoming slightly convex, usually delimited, (0.2-)0.3-0.7(-0.8) mm diam.; soralia without thalloidima green. --- Phlyctis argena (Spreng.) Flot.

117a (109) On rock --- 118
117b
On bark --- 130

118a Thallus isidiate or papillate, sometimes with apical soralia --- 119
118b
Thallus sorediate, soralia not apical on papillae --- 122

119a Isidia present, slender, cylindrical, 0.1-0.3 mm thick, simple to branched --- 120
119b
Papillae present --- 121

120a Thallus pale grey; C-, UV-; thamnolic acid --- see P. corallina 17a
120b Thallus pale yellowish grey; C+ orange, UV+ dark red; thiophaninic acid; on top of more or less calcareous, schistose boulders, Scotland, Sweden, Norway, rare --- 4/P. flavocorallina Coppins & Muhr

121a Papillae mammiform, with white soralia on top --- see P. mammosa 18a
121b Papillae semiglobose to short cylindrical, 0.5-1 mm thick, usually without soralia --- see P. stalactiza 18b

122a Thallus C+ yellowish to orange, with rounded soralia --- 123
122b
Thallus C-, mostly P+ red, KC+ pink (protocetraric, fumarprotocetraric and/or succinprotocetraric acid); soralia various --- 125

123a Thallus thin, pale grey, initially radiately rimose, later rimose-areolated; soralia not dense, at first small, pale and fleck-like, becoming diffuse and contiguous; thallus weakly bitter, KC+ orange; thiophaninic, stictic, menegazziaic, tr. norstictic acids; looks like P. amara; Italy, Britain; syn. P. affinis Erichsen --- 2/4/5/P. amarescens Nyl.
123b Thallus sulphur-yellow to yellow-grey, C+ yellow, KC+ yellow, UV+ orange, more or less warty, rimose-areolated, with mostly irregularly rounded, yellowish, sometimes confluent soralia; thiophaninic acid sometimes with other xanthone or stictic acid (+ norstictic, constictic); mostly in steep faces of non- to weakly calcareous rock --- (P. flavicans) 124

124a Thallus thin, smooth, yellowish to yellow-grey or greenish grey, with small to 1 mm wide areoles and usually scattered, flat soralia; on calcareous schist and siliceous limestone in the alpine and upper alpine zone of the Alps --- 1/2/4/5/P. flavicans Lamy v. schistosa Erichsen
124b Thallus thicker, always yellowish to yellowish green, at most in shade forms grey, with irregular, often confluent soralia; widespread on non-calcareous rock in the Mediterranean, occasionally in warmer parts of Central Europe --- v. flavicans

125a On limestone or gypsum --- 126
125b
On siliceous stone; always P+ red --- 127

126a On limestone; thallus thick, whitish, not areolated, at most finely rimose, with larger, 1-2 mm wide, sorediate warts and smaller, 0.4-0.6 mm wide, basally constricted, not sorediate warts; protocetraric, succinprotocetraric acids; on limestone in Tyrol --- 5/P. pseudolactea Erichsen
126a On gypsum; thallus blackish, sharply delimited; soralia small, punctiform, 0.1-0.2 mm wide, dirty greenish; medulla K+ yellow; no substances; north Germany; = Lecanora sp. --- 5/7/P. gypsicola Erichsen

127a Fumarprotocetraric acid major, protocetraric acid minor --- 128
127b
Protocetraric acid major --- 129

128a Thallus grey, moderately thick, rimose-areolate, irregularly fine- to coarse-warted, with almost concolorous, coarse soralia on viz. between the warts; soralia yellowish white, 0.5-0.8 mm wide; fumarprotocetraric, tr. protocetraric acids; on granite in Rumania --- 2/5/P. erumpens Erichsen
128b Thallus grey, rather thin, areolated or not, smooth to finely warty-scabrid, with irregular, often confluent, yellowish white soralia, additionally isidiate; fumarprotocetraric, sometimes with succinprotocetraric acid major; scattered on non-calcareous boulders in temperate Europe, variable; syn. P. dealbescens Erichsen, P. dealbata Auct., P. leucosora Auct. --- P. aspergilla (Ach.) J.R.Laundon

129a Thallus areolated, whitish to ash-grey, with large, about 1-1.5 mm wide, dense soralia; protocetraric acid; syn. P. albescens (Huds.) Choisy et Wern. v. subflotowiana (Erichs.) --- 2/5/P. leucosora Nyl.
129b Thallus rimose, not areolated, with whitish, to 1.5 mm wide, coarse-granular to isidiate soralia; protocetraric acid; fertile warts common, to 0.2 mm wide, with up to 3 discs and sorediate margin; ascospores 2/ascus, about 100-150 x 50-70 Ám; medulla J- or J+ bluish; W. & S. Alps --- 2/5/P. digrediens Nyl.

130a (116) Thallus fine- to coarse-isidiate, isidia not soon disintegrating into soredia, occasionally with additional rounded to irregular soralia --- 131
130b
Thallus not isidiate, or with soon disintegrating, isidium-like pustules --- 132

131a Thallus sulphur-yellow to yellow-grey, UV+ orange, uniformly covered by fine, somewhat globular, about 0.5 mm wide isidia, occasionally with finely sorediate, yellowish outbursts; thallus grey at the border; thallus C+ yellow to orange, KC+ yellow to orange, UV+ bright orange; (3 strains) thiophaninic acid, without or with stictic acid, confluentic or 2'-O-methylperlatolic acids and traces; discs very rare, 2-4 together immersed in semiglobose, sorediate fertile warts; ascospores usually 8/ascus, about 60-100 x 25-40 Ám; on bark of deciduous trees in oceanic or warm parts of Europe, absent from cool regions, variable; syn. P. lutescens (Hoffm.) Lamy --- 1/2/4/5/P. flavida (DC.) J.R.Laundon
131b Thallus yellowish green-grey, with scattered, more coarse, rounded to coralloid-elongate isidia, KC- --- see P. coronata 64a

132a Thallus without distinctly delimited, more or less rounded soralia, completely covered by soredia except at the border --- 133
132b
Thallus with more or less distinctly delimited soralia --- 139

133a Thallus without papillae, isidia or such, but largely sorediate --- 134
133b
Thallus with isidia, papillae or nodulose excrescences --- 137

134a Thallus sulphur-yellow; thallus very thin, uniformly fine-sorediate, the soredia about 0.2 mm wide, sulphur yellow, KC+ yellow to brownish, C-, P-; atranorin, indet. substances; central Europe; not in Pertusaria, aff. Lecanora? --- 5/P. pulvureo-sulphurata Harm.
134b Thallus not sulphur-yellow --- 135

135a Thallus P- or P+ orange to red --- 136
135b
Thallus P+ citron yellow, thin, grey-whitish, finely rimose (to areolate), warty; cortex from the beginning dissolved; surface finally confluently sorediate, soralia with pale brownish tinge; on Acer, East Prussia --- P. dissoluta Erichsen

136a Thallus rather thick, delimited, at the border with a few distinct soralia, in the center covered by brownish grey soredia 0.08-0.12 mm large; apothecia very rare, in semiglobose, sorediate warts; widespread on roadside trees; syn. P. leprarioides Auct. --- Ochrolechia turneri (Sm.) Hasselr.
136b Thallus yellow- to grey-green, often shelf-like rimose-areolated, the areoles uniformly sorediate with about 40-70 Ám thick soredia, K+ yellow, P+ yellow to red, C-; fumarprotocetraric acid; on coniferous trees, with boreal-montane distribution; syn. P. miniescens Erichsen --- 5/Catillaria pulverea (Borr.) Lettau

137a Thallus thickish, whitish grey, with fine-grained, dense, whitish papillae which may become sorediate; transgressing into typical variety --- 2/P. albescens (Huds.) M.Choisy v. corallina Zahlbr.
137b Like P. albescens var. corallina, with different set of fatty acids iH (similar to P. panyrga); endemic in SW Ireland --- 4/P. polythecia (Tayl.) Erichsen
137c Thallus with thicker, basally constricted excrescences --- 138

138a Thallus whitish, with 0.5-1 mm wide, semiglobose, in part sorediate, scattered or dense warts; soralia whitish to greenish grey; on free-standing trees in central and southern Europe probably widespread; syn. P. jurana Erichsen --- see P. albescens 141b
138b Thallus large, with more or less globose, to 4 mm high and 5 mm wide, apically sorediate, nodulose excrescences; fatty acid bH; rather frequently fruiting; fertile warts soralium-like; ascospores 1/ascus, about 140-250 x 50-85 mm; on old Fagus usually in larger forests in central Europe; syn. P. albescens f. tuberculata (Erichsen). --- 5/7/P. tuberculata (Erichs.) Erichs

139a (132) Thallus or soralia P+ yellow to red or blue-grey --- 140
139b
Thallus and soralia P- --- 141

140a Thallus yellowish grey, in the center densely covered with irregularly rounded, to 1 mm wide, yellowish soralia, towards the border radiately rimose and often with elongate soralia along the fissures; thallus K+ yellow, soralia K+ orange, P+ yellow to red; on Fagus in the Carpathians --- P. obtecta Erichsen
140b Thallus grey, grey-green; soralia often irregularly deformed to confluent, pale flesh-coloured white, P+ blue-grey, on ashy grey to brownish thallus; on Fagus in the Vosges (according to Hanko 1983) a synonym of Lecanora impudens, containing atranorin and an indet. trace) --- P. cinereocarneola Harm.

141a Soralia small, to about 1 mm wide, scattered; thallus weakly yellowish grey; variolaric and lichesterinic acids; on bark of old coniferous trees in boreal-montane regions, nitrophobic; syn. P. decipiens Erichs. --- Ochrolechia alboflavescens (Wulfen) Zahlbr.
141b Soralia larger, P-; thallus strong, often extensive, grey-greenish (in shade) to whitish grey; fatty (allopertusaric, dihydropertusaric) acids, traces; apothecia very rare, in soralium-like fertile warts; discs single or with several together; ascospores 1/ascus, about 170-300 x 50-115 Ám; preferably in deciduous trees in light forest and gardens, common and variable; syn. P. discoidea (Pers.) Malme. --- (P. albescens) 142

142a Thallus border several times zoned; soralia to 2 mm wide, usually slightly convex; thallus often grey-greenish; mainly in light forest; not sharply delimited from typical variety --- 1/2/3/4/5/P. albescens (Huds.) Choisy et Werner v. globulifera (Turn.)
142b Thallus border usually not zoned; soralia usually well over 2 mm wide, to 6 mm wide, often concave and thus with distinct thalline margin; thallus greyish white; mainly in gardens and along streets --- v. albescens
142c
Thallus border not zoned; thallus radially fissured, seemingly lobed; soralia scattered, rounded, concave, farinose, 0.5-2 mm wide, transient into 1.5-2 mm wide aborted fertile warts with flesh-coloured discs; Rumania, on old Fagus; = P. deschatresii Werner from Fagus on Corsica? --- P. dacica Erichsen

143a (1) Thallus without isidia or soredia, usually with apothecia --- 144
143b
Thallus with isidia or soralia, usually without apothecia --- 150

144a Apothecia when fully developed with distinctly widened discs, not perithecium-like --- 145
144b
Apothecia persistently perithecium-like, with punctiform discs (ostioles), usually several in each fertile wart --- 146

145a Ascospores 2/ascus; on soil over calcareous shale; thallus pale grey, continuous or somewhat cracked-areolated, 0.4-1mm thick; areoles (0.4-)0.8(-1.2) mm wide; isidia and soralia absent; surface matt, slightly tuberculate; margins not zoned; P-, K-, C-, KC-, UV-; 2'-O-methylperlatolic acid; fertile warts lecanorine, 0.6-1(-2) mm wide, more or less aggregated; discs black, somewhat immersed and warty, (0.4-)0.8(-01.4) mm wide, usually single; ascospores 2(-4)/ascus, about 50-160 x 40-60 Ám, with fine concentric or radial striation; Tyrolia --- P. christae Dibben & Poelt
145b Ascospores 1/ascus, usually over 100 m long; usually over calcareous substrate; thallus whitish, warty, often largely covered by semiglobose fertile warts with to 3 mm wide, rounded, yellow- to dark brownish discs; thallus K-, P-, C+ reddish, UV+ more or less glaucous to orange; gyrophoric acid with xanthone dH or stictic (+ accessories); apothecium margin initially swollen, later reduced; ascospores about 150-over 200 x 60-100 Ám; Arctic, Alps and Carpathians, widespread but scattered --- 1/2/4/5/P. bryontha (Ach.) Nyl.

146a Thallus K+ yellow->fast red (norstictic acid) --- 147
146b
Thallus K+ yellow or K- (no norstictic acid) --- 149

147a Fertile warts always present; ascospores 4/ascus; epithecium K+ violet --- 148
147b
Fertile warts rare; thallus P-; epithecium K- or pale violet; ascospores 2/ascus, 160-230 x 50-75 Ám; thallus rather thick, cartilaginous-parchmenty, whitish, slightly glossy; norstictic acid, sometimes with xanthone dH; Arctic to Scandinavia, widespread but probably much overlooked --- 1/5/P. coriacea (Th.Fr.) Th.Fr.

148a Ascospores mostly 4/ascus, about 70-125 x 25-50 Ám; thallus whitish, usually completely covered by the almost globose, about 1 mm wide, dense fertile warts, which contain usually a single, dark ostiole; thallus P+ yellow, K+ yellow-red, C-, KC+ yellow-red, UV+ glaucous; norstictic acid, sometimes with tr. stictic; mainly on calcareous soil in the Arctic and Subarctic, Sudetes, Alps, Carpathians, French Jura, usually scarce --- 1/2/5/P. glomerata (Ach.) Schaer.
148b Ascospores 8/ascus, about 60-90 x 10-50 Ám; like P. glomerata, with to 0.8 mm wide fertile warts; thallus P+ slowly yellowish; norstictic acid with tr. stictic; other strain with xanthon dH and stictic acid; northern Fennoscandia --- 1/5/P. octomela (Norm.) Erichsen

149a Ascospores about 30-60 x 25-35 Ám; discs at first punctiform, later widened, blackish; paraphyses simple to little branched; thallus whitish, P-, with dense, almost semiglobose fertile warts; no substances; syn. P. freyi Erichs. --- 5/Megaspora verrucosa (Ach.) Hafellner & V.Wirth
149b Ascospores about 50-90 x 25-50 Ám; thallus scarce, P-, white, covered by to 0.9 mm wide, flattened globose fertile warts containing usually 1 ostiole; coronaton, tr. stictic acid?; northern Fennoscandia, Scotland, Alps; in Alps also a powdery-sorediate form --- 1/5/P. trochiscea Norm.

150a (143) Isidia present --- 151
150b
Soredia present --- 153

151a Thallus K-, C-, P-, with fatty acids iH, whitish, with c. 0.6 mm wide isidia without dark tips, with dense, basally constricted, somewhat columnar, 0.8-1 mm wide fertile warts with mostly 2-3 black, 0.4-0.6 mm wide discs; ascospores about 80-165 x 40-55 Ám; common and widespread in the Arctic, also in Scandinavia, Scotland; syn. P. efflorescens Vain. --- 1/4/5/P. panyrga (Ach.) A.Massal.
151b Thallus K+ yellow, P+ orange to red --- 152

152a Ascospores (6-)8/ascus, usually under 50 Ám long; thallus whitish grey, with numerous, about 0.3-0.4 mm thick, 1-3 mm long, fragile, dark-tipped isidia, K+ yellow becoming rusty red, P+ yellow becoming orange, C+ pink or C-, KC+ yellow-red; fumarprotocetraric, tr protocetraric or gyrophoric acids; apothecia 1-2 mm wide, with blackish disc and strong margin; ascospores about 23-30 x 10-14 Ám; on acid substrate, widely distributed and not rarely fruiting in the Arctic and Subarctic, in the Alps only in the central, non-calcareous parts and here mostly sterile, similarly in the Sudetes, Carpathians, Balkans --- 1/2/4/5/P. oculata (Dicks.) Th.Fr.
152b Ascospores 2/ascus; thallus whitish, thin, covered with erect, dense, coarse, columnar, to about 3 mm tall and about 0.5-0.6 mm thick isidia with white tips; P+ red, K+ yellowish, C-, KC- or + pink, UV-; fumarprotocetraric with or without tr. protocetraric acid, sometimes lepraric acid; apothecia usually single, immersed in the tips of isidia, with rounded, blackish, about 0.5 mm wide disc; ascospores 1/ascus, about 120-300 x 60-100 Ám long; on acid substrate, sometimes on bark, in the Arctic widespread, reaching Iceland, Fennoscandia, Nowaja Semlja --- 1/4/5/P. dactylina (Ach.) Nyl.

153a Thallus pinkish, consisting of scattered to crowded granules 0.1-0.2 mm wide, apically bursting and sorediate; thallus P+ yellow-orange, K+ yellow, C+ red, KC+ red, UV-; alectorialic, barbatolic acids, sometimes xanthones; apothecia rare, to 2.5 mm wide, single in a fertile granule, with dark red to purplish black disc; epithecium red-brown, K+ paler, dissolving; ascospores 2/ascus, 22-40 x 15-20 Ám; arctic-alpine, occasionally on bark --- 1/2/4/P. geminipara (Th.Fr.) C.Knight ex Brodo
153b Thallus grey to whitish grey, continuous; soredia spread over larger parts of thallus --- 154

154a Thallus to 6 mm thick, finely branched, the branches dense, entangled, interconnected, K+ yellow; branch surface warty, warts 0.4-0.6 mm wide, confluent, finally sorediate but not producing distinct soralia; gyrophoric, tr. lecanoric acids?; Tirol --- 5/P. tiroliensis Erichsen
154b Thallus scarce, different; coronaton present --- see P. trochiscea Norm. 149b

 

not treated:

1/5/P. degelii Erichsen: gyrophoric, tr. lecanoric acids, perhaps belonging in Ochrolechia; not in Santesson (1993)
5/P. diaxantha Nyl.: usnic acid, atranorin; Karelia (= Mycoblastus)
P. djidjelliana Flagey: Algeria, on rock; no apothecia, no isidia, no soredia, K+ pale yellow; available information insufficient for inclusion in key.
5/P. hibernica Erichsen: gyrophoric, variolaric, tr. lecanoric acids; probably belonging in Ochrolechia; not accepted by Purvis et al. (1993).
P. werneri Bertrand & Prone: Vosges, France; description not seen; not accepted by Clauzade & Roux 1985.

 

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Zschacke, H. 1927. Korsische Flechten, gesammelt in den Jahren 1914-16. Verhandl. Bot. Ver. Brandenb. 69: 1-129.

 

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