Introduction
The lichen biota of Western Europe is probably better studied and understood than any other region worldwide but collections of apparently undescribed species still occur with surprising regularity (e.g. Fryday & Coppins Reference Fryday and Coppins2012; van den Boom et al. Reference van den Boom, Brand, Coppins and Sérusiaux2017). Among these are five collections of a novel saxicolous species, made between 1993 and 2001 in maritime areas of the Atlantic and Mediterranean coasts from north-west Italy to western Ireland. The new species could easily be mistaken in the field for a species of Porpidia Körb. but it is microscopically very distinctive because it possesses simple paraphyses that are pigmented in the upper 10–25 μm. As this combination of characters is unique, we also suspect that these collections represent a distinct lineage. However, as molecular data are lacking, we chose not to erect a new genus but instead to describe them in a broadly-circumscribed Lecidea.
Materials and Methods
This study was based on specimens collected by the second author and by Maarten Brand (Leiden, the Netherlands). They were compared with specimens held in the herbarium of Michigan State University (MSC). Apothecial characteristics were examined by light microscopy on hand-cut sections mounted in water, 10% KOH (K), 50% HNO3 (N), 15% HCl (H) or Lugol's reagent (0·15% aqueous IKI). The ascus structure was studied in IKI, both without and after pretreatment with K. Measurements of ascospores and paraphyses were made in K. Ascospore measurements are given in the format (lowest observed–) arithmetic mean ± standard deviation (–highest observed). Mean values are presented in bold.
The Species
Lecidea phaeophysata Fryday, van den Boom & M. Brand sp. nov.
MycoBank No.: MB 828933
Characterized by the Porpidia-type asci, narrow ellipsoid ascospores and simple paraphyses with the upper 10–25 μm pigmented.
Type: Italy, Liguria, Sestri Levante, S. Anna, c. 0·2 km from sea, near path to Roman bridges, 44°17′N, 9°22′E, 10 m, sandstone, of steep side (sic), in open Pinus woodland, 21 July 1993, M. Brand 30100 (L—holotype; hb. Brand, hb. v. d. Boom—isotypes).
(Fig. 1)
Thallus effuse, up to 5 cm diam., chasmolithic or thin diffuse, pale greenish when fresh, creamish to brown in the herbarium; medulla I−. Photobiont chlorococcoid; cells 9–12 μm diam.
Fig. 1. Lecidea phaeophysata (Brand 30100—holotype). A, general view of thallus and apothecia; B, immature apothecia; C, mature apothecia; D, section through apothecium (in H2O); E, section through exciple (in H2O); F, paraphyses (in H2O); G, immature ascus (in IKI); H, mature ascus (in H2O). Scales: A–C = 1 mm; D = 100 μm; E = 20 μm; F–H = 10 μm. In colour online.
Apothecia (Fig. 1A–C) abundant, sessile, lecideine, c. 0·6–1·1 mm diam., black with plane, matt disc and slightly raised shiny margin, constricted below, especially in mature apothecia; proper margin 0·07–0·10 mm wide, prominent when young, occasionally becoming excluded in old apothecia. Only fuscous brown pigments present internally (Fig. 1D); pigment little changed in K or N although slightly paler in K and more orange-brown in N. Excipulum (Fig. 1E) well developed, c. 60–70 μm wide, cupular, continuous below the hypothecium, composed of parallel, radiating hyphae c. 5–6 μm wide with brown extracellular granules; cortical cells 7–10 μm diam. Hymenium 55–65 μm tall, paraphyses (Fig. 1F) c. 2·0–2·5 μm wide at the base and apex, thinning somewhat to c. 1·5–2·0 μm wide in mid-hymenium, unbranched, septate, cells c. 10 μm long, occasionally constricted at the septum, not capitate or strongly conglutinated, upper 10–25 μm pigmented fuscous brown, pigment sometimes extending all the way down to the hypothecium. Asci cylindrical, 35–50 × 10–12 μm, Porpidia-type (Fig. 1G, H), amyloid tube not reaching all the way to the apex in immature asci (Fig. 1G). Ascospores hyaline, ellipsoid, (11–)14·33 ± 1·67(–18) × (4·0–)4·79 ± 0·50(–5·5) μm (n = 12), perispore absent. Hypothecium brown, c. 100 μm tall; dark below composed of randomly-orientated hyphae, becoming paler with increasingly vertically-orientated hyphae towards the hymenium; hyphal pigment the same as that of the upper paraphyses.
Conidiomata uncommon, seen on only one collection (Brand 38356), flat, brown, 0·6–0·8 mm diam., sometimes with a gaping ostiole; conidia filiform, curved c. 14–16 × 0·5–0·6 μm.
Chemistry
K−, C−, KC−, Pd−, UV+ yellow (?carotenoids); thallus too scant for TLC.
Etymology
The name is derived from the dark pigmentation of the upper part of the paraphyses.
Distribution and ecology
The new species is widely distributed on the Atlantic coast of Western Europe from Ireland to Portugal, with one locality in Southern Europe on the Mediterranean coast in NW Italy (Fig. 2). It is found on siliceous rock in maritime areas mainly on or near the coast, on N-sloping overhanging acidic rocks, with only the Irish collection (Brand 40679) being more than 2 km from the sea, on an overhang near the entrance of a cave. The type specimen locality is situated on steep sandstone. In other areas it has possibly been overlooked, being mistaken for a species of Porpidia or other lecideoid species. However, it can be distinguished from these in the field by its apothecia having a narrow base which leaves the margins and much of the underside free of the substratum.
Fig. 2. Map of Europe showing localities of collections of Lecidea phaeophysata.
No other lichens are present on the type collection but there are saxicolous species associated with the other collections including: Micarea botryoides (Nyl.) Coppins, Micarea prasina Fr. s. lat. and Gyrographa gyrocarpa (Flotow) Ertz & Tehler (Ireland); and Amandinea pelidna (Ach.) Fryday & L. Arcadia, Cliostomum tenerum (Nyl.) Coppins & S. Ekman, Dirina cf. fallax De Not., Lecanora praepostera Nyl., L. subcarnea (Lilj.) Ach. and Roccellographa circumscripta (Taylor) Ertz & Tehler (France). The collection from Portugal is from the small rocky hill of São Bartolomeu, where van den Boom (Reference van den Boom2006) recorded 228 species on a wide range of substrata, including acidic rock.
Additional specimens examined. France: Brittany: Département du Mobihan, Ile de Groix, 4 km W of Port Tudy, Beg-Melen, just E of semaphore, 47°39·2′N, 3°30′W, 40 m, mica-schist rock, high cliff above sea (exp. N), vertical to overhanging face, 1999, A. M. Brand 38356 (hb. Brand); Département d'Ille-et-Vilaine, 8 km ENE of St Malo, Pointe du Meings, N-side, 48°42·1′N, 1°55·8′W, gneiss rocks of headland, N-sloping rocks, 28 April, 1999, A. M. Brand 38864 (hb. Brand, hb. v. d. Boom).— Ireland: Galway: Connemara, Twelve Pins, S slope of Muckanaght, near saddle to Benbrack, 53°31·5′N, 9°51·4′W, 350 m, mica-schist rocks on N-exposed slope, overhang near entrance of cave, 2000, A. M. Brand 40679 (hb. Brand, hb. v. d. Boom).—Portugal: Leiria: 2·7 km E of Nazaré, São Bartolomeu, small rocky hill, 39°35·4′N, 9°3·7′W, 100 m, W-exposed rocky slope along Pinus pinaster forest, steep rock face and boulders, 2001, P. & B. van den Boom 27778 (hb. v. d. Boom).
Discussion
The combination of Porpidia-type asci and simple, non-captitate paraphyses with the upper section having a fuscous brown pigment appear to be unique to the new species. The Porpidia-type asci suggest a placement in the Lecideaceae but Lecidea phaeophysata does not fit comfortably in any described genus of that family. Clearly it does not belong to Lecidea Ach. s. str. because of the ascus type, and the genus Porpidia Körb. differs in having richly branched and anastomosing paraphyses; Farnoldia Hertel also differs in its carbonaceous exciple and capitate paraphyses. Bryobilimbia Fryday et al., which also has Porpidia-type asci and ± simple, non-capitate paraphyses, is superficially similar and we initially planned to describe our new species in that genus. However, closer inspection revealed a number of significant differences between our new species and species of that genus. In particular, the epihymenial region of the paraphyses of Bryobilimbia is dilute brown or unpigmented which contrasts strongly with the pigmentation of the paraphyses in L. phaeophysata that regularly extends 10–25 μm into the hymenium, and often the entire length of the paraphysis through to the hypothecium is pigmented (Fig. 1F). In addition, the exciple of Bryobilimbia species is less strongly pigmented than the hypothecium and the excipular hyphae are much wider (6–10 μm) than those of L. phaeophysata. The pigment present in the exciple and hypothecium of Bryobilimbia species is reddish brown and K+ orange (?Superba-brown) and is clearly different from the fuscous brown pigment in our new species. The only Northern Hemisphere species of Bryobilimbia that commonly occurs on rocks, B. ahlesii (Körb.) Fryday et al., is readily distinguished from the new species, even in the field, by its brown apothecial disc (especially when wet), a consequence of the dilute brown or unpigmented epihymenium, and is further distinguished microscopically by its broader ascospores ((5–)6–7(–9) μm; Aptroot et al. Reference Aptroot, Gilbert, Hawksworth, Coppins, Smith, Aptroot, Coppins, Fletcher, Gilbert, James and Wolseley2009). Also similar to L. phaeophysata is Clauzadea Hafellner & Bellem. but species of that genus occur on limestone, have branched and anastomosing paraphyses and the same reddish brown (K+ orange-brown) pigment as Bryobilimbia. Other genera with Porpidia-type asci that are similar to Bryobilimbia (Lecidea berengeriana group, Lecidoma Gotth. et al., Romjularia Timdal) are all terricolous or bryicolous species and also differ in the pigmentation of their paraphyses (Fryday et al. Reference Fryday, Printzen and Ekman2014).
In the key to lichens of siliceous rocky shores (Fletcher Reference Fletcher1975), Lecidea phaeophysata would key out as Porpidia crustulata (Ach.) Hertel & Knoph but it differs from that species, macroscopically, by the larger apothecia (typically 0·3–0·8 mm diam. in P. crustulata; Fryday et al. Reference Fryday, Gilbert, Galloway, Coppins, Smith, Aptroot, Coppins, Fletcher, Gilbert, James and Wolseley2009) with a constricted base and, microscopically, by the simple paraphyses with pigmented upper section and the fuscous brown rather than red-brown pigment.
Between 1875 and 1878, Charles Larbalestier collected lichens extensively in Connemara (Mitchell Reference Mitchell1998), including the area where one of the collections of L. phaeophysata (Brand 40679) was made. Nylander described numerous new species of Lecidea from these collections (see References in Mitchell (Reference Mitchell1998)) but perusal of 18 of these publications (including 10 containing species collected by Larbalestier and others containing species collected by Carroll or Hitchins) revealed nothing that could be an earlier name for L. phaeophysata. Nylander had a very wide concept of Lecidea that included species with septate spores and many of these taxa are now referred to other genera (e.g. Bacidia, Buellia, Catillaria, Lecania, Micarea, etc.) whereas others had already been reduced to synonymy with different species or the descriptions included characters (e.g. hyaline hypothecium, smaller or larger ascospores) that were incompatible with L. phaeophysata. The only species that could possibly have been an earlier name for L. phaeophysata was L. valentior Nyl., but that name has already been shown to be a synonym of Bryobilimbia ahlesii (Meyer Reference Meyer2002). The lectotype of L. valentior in H-Nyl was checked and this determination found to be correct.
The pigment present in L. phaeophysata appears most similar to Arnoldiana-brown (Meyer & Printzen Reference Meyer and Printzen2000) but that pigment is reddish brown in water and changes between reddish brown at low pH and dark brown at high pH after pretreatment with either K or N. The pigment in L. phaeophysata is fuscous brown in water and changes little at low pH and high pH after pretreatment with K (somewhat lighter at low pH), although it does also change between reddish brown at low pH and dark brown at high pH after pretreatment with N.
Keys to saxicolous lecideoid lichens present on European Atlantic coasts
To aid identification of our new species and assist in separating it from other lecideoid species, we are providing keys to lichens that occur in the same or similar habitat. These keys include those lichen taxa with lecideine apothecia and either simple or septate spores, but exclude species of Teloschistaceae.
The decision as to which species to include was based on those species included in the keys of Fletcher (Reference Fletcher1975) and on our own field experience. Measurements of apothecia, ascospores etc. are mostly taken from Smith et al. (Reference Smith, Aptroot, Coppins, Fletcher, Gilbert, James and Wolseley.2009).
Ascospores simple………………………Key A
Ascospores septate………………………Key B
Key A: saxicolous species with non-septate ascospores
1 Thallus C+ red (gyrophoric acid) or C+ orange (xanthones)………………………2
Thallus C−………………………11
2(1) Thallus C+ red, white, light to dark grey, or brown………………………3
Thallus C+ orange, yellow-green (Lecidella spp.)………………………9
3(2) Apothecia black………………………4
Apothecia brown (Trapelia and Trapeliopsis spp.)………………………7
4(3) Thallus shiny, with an epinecral layer; apothecia adnate to sessile; paraphyses ± simple………………………5
Thallus matt, without an epinecral layer; apothecia innate; paraphyses branched and anastomosing………………………6
5(4) Thallus grey………………………Lecidea grisella
Thallus brown………………………Lecidea fuscoatra
6(4) Thallus white; cephalodia present………………………Amygdalaria pelobotryon
Thallus dark grey; cephalodia absent………………………Schaereria fuscocinerea
7(3) Thallus thin, continuous………………………Trapelia coarctata*
Thallus thicker, placodioid or subsquamulose………………………8
* The genus Trapelia in Europe was recently revised (Orange Reference Orange2018) but as the distributions of the species segregated in that work are currently unclear, we treat only the species in their traditional circumscription.
8(7) Thallus white, placodioid, usually terricolous; apothecia rare………………………Trapeliopsis wallrothii
Thallus brown-grey, subsquamulose, usually saxicolous; apothecia frequent; ascospores 15–26 × 7–12 μm………………………Trapelia glebulosa
9(2) Thallus sorediate………………………Lecidella scabra
Thallus not sorediate………………………10
10(9) Thallus of corticate granules………………………Lecidella asema
Thallus of blastidia………………………Lecidella meiococca
11(1) Thallus K+ red or Pd+ red or yellow………………………12
Thallus K+ yellow or K−, Pd−………………………15
12(11) Thallus K+ red (red crystals in section; norstictic acid)………………………13
Thallus K−, Pd+ bright yellow or red………………………14
13(12) Apothecia ±pruinose; paraphyses simple; ascospores non-halonate………………………Lecidea lactea
Apothecia pruinose; paraphyses branched and anastomosing; ascospores halonate………………………Porpidia platycarpoides
14(12) Thallus shades of brown, Pd+ red (fumarprotocetraric acid); apothecia brown, sessile; ascospores bean-shaped………………………Fuscidea cyathoides
Thallus white, Pd+ bright yellow (psoromic acid); apothecia black, ±immersed; ascospores ellipsoid………………………Lecidea phaeops
15(11) Thallus rust red………………………16
Thallus white or grey or green, if reddish only patchily due to oxidization………………………17
16(15) Thallus composed of bullate areoles; apothecia becoming sessile .. Lecidea silacea
Thallus of flat areoles; apothecia innate………………………Tremolecia atrata
17(15) Medulla I+ violet………………………18
Medulla I−………………………22
18(17) Thallus with tuberculate soralia………………………Porpidia tuberculosa
Thallus lacking soralia………………………19
19(18) Ascospores narrow ellipsoid, <4 μm wide………………………20
Ascospores broad ellipsoid, >5 μm wide………………………21
20(19) Exciple C+ red (2′-O-methylanziaic acid)………………………Lecidea diducens
Exciple C−………………………Lecidea auriculata
21(19) Apothecia innate; paraphyses branched and anastomosing; confluentic acid present (K+ oil droplets in section)………………………Porpidia speirea
Apothecia sessile; paraphyses simple; stictic acid present (K+ yellow solution in section)………………………Lecidea lapicida
22(17) Asci multi-spored, >100 ascospores per ascus; apothecia red-brown, blue-grey pruinose………………………Sarcogyne regularis
Ascospores 8 per ascus………………………23
23(22) Epihymenium K+ crimson; apothecia orange or red (Protoblastenia sp.); on calcareous rocks………………………24
Epihymenium not K+ crimson; apothecia black or brown; on calcareous or acidic rocks………………………26
24(23) Thallus distinctly epilithic, often cracked………………………Protoblastenia rupestris
Thallus endolithic to weakly epilithic………………………25
25(24) Apothecia immersed to semi-immersed in the rock, small, 0·2–0·5 mm, concave, plane or weakly convex.………………………Protoblastenia incrustans
Apothecia sessile, large, 0·4–1·6 mm, convex to strongly convex .. Protoblastenia calva
26(23) Apothecia rare; pycnidia frequent………………………27
Apothecia frequent………………………28
27(26) Pycnidia stalked; over bryophytes in shaded areas………………………Micarea botryoides
Pycnidia sessile; on rock………………………Herteliana gagei
28(26) Thallus composed of green goniocysts………………………Micarea prasina agg.
Thallus not composed of green goniocysts………………………29
29(28) Paraphyses lax in K (Lecidella spp.)………………………30
Paraphyses ±conglutinate………………………31
30(29) Hypothecium brown; thallus well developed, white……………Lecidella carpathica
Hypothecium hyaline; thallus poorly developed or endolithic, greyish………………………Lecidella stigmatea
31(29) Ascospores large, >70 μm long, < 8 per ascus; red pigment present below apothecia………………………Mycoblastus sanguinarius
Ascospores smaller, 8 per ascus; red pigment absent………………………32
32(31) Hypothecium hyaline………………………33
Hypothecium pigmented………………………36
33(32) Thallus whitish………………………34
Thallus dark grey or greenish yellow………………………35
34(33) Apothecia angular with thin proper margin; paraphyses ±simple………………………Lecidea lithophila
Apothecia rounded with thicker proper margin; paraphyses branched………………………Miriquidica leucophaea
35(33) Thallus dark grey………………………Fuscidea lygaea
Thallus greenish yellow………………………Lecanora sulphurea
36(32) Hymenium with red, K+ purple pigment………………………Lecidea sarcogynoides
Hymenium ±hyaline………………………37
37(36) Apothecia <0·5 mm, hymenium <50 μm (Micarea spp.)………………………38
Apothecia >0·5 mm, hymenium >50 μm………………………39
38(37) Thallus epilithic, grey; apothecia usually with distinct proper margin………………………Micarea erratica
Thallus ± endolithic; apothecia globose, proper margin ±absent………………………Micarea lutulata
39(37) Paraphyses simple, upper 20 μm pigmented………………………Lecidea phaeophysata
Paraphyses branched and anastomosing………………………40
40(39) On ±calcareous substrata; hypothecium paler than exciple, only brown pigments internally………………………41
On siliceous substrata; hypothecium and exciple concolorous, greenish pigments often present internally (Porpidia spp.)………………………43
41(40) Apothecia immersed in the substratum………………………Clauzadea metzleri
Apothecia sessile………………………42
42(41) Hymenium usually with violet (K+ blue) granules; ascospores often 1-septate ………………………Bryobilimbia hypnorum
Hymenium lacking violet (K+ blue) granules; ascospores never septate………………………Clauzadea monticola
43(40) Exciple with hyaline medulla, excipular hyphae 2–3 μm wide………………………44
Exciple pigmented throughout, excipular hyphae wider………………………45
44(43) Epihymenium bright blue; thallus lacking lichen substances; not sorediate………………………Porpidia hydrophila
Epihymenium olivaceous or brown; thallus containing 2′-O-methylsuperphyllinic acid; often sorediate………………………Porpidia rugosa
45(43) Exciple medulla pale brown, less pigmented than cortex; paraphyses richly branched and anastomosing; stictic acid or no substances present………………………46
Exciple ±uniformly dark; paraphyses sparingly branched and anastomosing; confluentic acid or methyl 2-O-methylmicrophillinate present………………………47
46(45) Proper margin thin and barely raised, <0·08 mm wide; mature apothecia <1·5 mm diam.; thallus epilithic, thin………………………Porpidia crustulata
Proper margin thick and raised, >0·1 mm wide; mature apothecia >1·5 mm diam.; exciple pale to mid brown internally; thallus ± endolithic………………………Porpidia macrocarpa
47(45) Thallus containing confluentic acid (K+ oil droplets in section)………………………Porpidia cinereoatra
Thallus containing methyl 2′-O-methylmicrophillinate (K−)………………………48
48(47) Apothecia innate………………………Porpidia contraponenda
Apothecia sessile………………………Porpidia irrigua
Key B: saxicolous species with septate ascospores and brown to black apothecia
1 Ascospores hyaline………………………2
Ascospores brown………………………22
2(1) Ascospores 1-septate………………………3
Ascospores 3- or more septate or muriform………………………11
3(2) Apothecia marginate, sessile………………………4
Apothecia immarginate, immersed………………………Arthonia meridionalis
4(3) Medulla I+ violet………………………5
Medulla I−………………………6
5(4) Thallus brown with a grey-violet tinge, C+ red; apothecia up to 1 mm diam.; epihymenium K−………………………Rhizocarpon richardii
Thallus dark brown with a faint grey or pink tinge, C−; apothecia up to 0·7 mm diam.; epihymenium K+ purple-red………………………Rhizocarpon polycarpum
6(4) Apothecia 0·4‒0·8 mm diam.………………………7
Apothecia 0·2‒0·4 mm diam.………………………8
7(6) Thallus epilithic on siliceous rock; ascospores elongate-ellipsoid, 10‒15 × 3‒5 μm; hypothecium pale………………………Tylothallia biformigera
Thallus endolithic on limestone; ascospores ellipsoid, 9·5‒12·5 × 4·0‒5·5 μm; hypothecium reddish brown………………………Toninia athallina
8(6) Hypothecium hyaline………………………9
Hypothecium dark brown………………………10
9(8) Apothecia 0·1‒0·2 mm diam., excipulum green-black throughout; on siliceous rock………………………Catillaria atomarioides
Apothecia 0·1‒0·4 mm diam., excipulum pale at inner part; on limestone………………………Catillaria lenticularis
10(8) Ascospores (7·5‒)9·0‒12·0(‒15·0) × 2·5‒4·0 μm………………………Catillaria chalybeia
Ascospores 15‒18 × 7·0‒8·5 μm………………………Rhizocarpon infernulum
11(2) Ascospores with only transverse septa………………………12
Ascospores muriform………………………21
12(11) Ascospores 10‒17-septate, 60‒95 × 3‒4 μm………………………Bactrospora patellarioides
Ascospores 3‒7-septate; <60 μm long………………………13
13(12) Apothecia marginate; ascospores 3-septate; thallus pale grey to pale brown, squamulose………………………Toniniopsis aromatica
Apothecia immarginate or margin soon excluded; ascospores 3‒7-septate………………………14
14(13) Apothecia immarginate; ascospores 3–5-septate; thallus brown with faint mauve tinge………………………Arthonia phaeobaea
Apothecia margin present in young apothecia but soon excluded; thallus without faint mauve tinge………………………15
15(14) Ascospores 3-septate; thallus crustose………………………Toniniopsis mesoidea
Ascospores 3‒7-septate; thallus crustose or squamulose………………………16
16(15) Apothecia brown………………………17
Apothecia black………………………19
17(16) Ascospores needle-shaped, spirally twisted………………………Scoliciosporum umbrinum
Ascospores ellipsoid………………………18
18(17) Thallus irregularly granular-warted; apothecia common; ascospores 1–3(–5)-septate, narrowly fusiform, 14‒28 × 2‒3 μm………………………Lecania cuprea
Thallus of rounded, flattened or coralloid granules; apothecia rare; ascospores 3–7-septate, bacilliform, 30‒38 × 1·5‒2·0 μm………………………Bacidia scopulicula
19(16) Thallus black, minutely squamulose; prothallus dark bluish to black; ascospores 1‒3-septate………………………Placynthium nigrum
Thallus not black, squamulose; prothallus not visible………………………20
20(19) Thallus yellow-brown, C+ orange; paraphyses ±conglutinated………………………Toninia thiopsora
Thallus brown-grey, C−; paraphyses ±lax………………………Toninia squalida
21(11) Thallus white; apothecia up to 1 mm diam.; epihymenium olive brown; ascospores usually >35 μm long………………………Rhizocarpon petraeum
Thallus grey to brown; apothecia 0·4‒0·6 mm diam.; epihymenium olive green; ascospores <30 μm long………………………Rhizocarpon reductum
22(1) Thallus placodioid with marginal lobes 0·5–1·0 mm wide………………………23
Thallus crustose or without marginate lobes………………………24
23(22) Thallus with small marginal lobes, up to 0·5 mm wide; apothecia immersed, often with a white pruina; ascospores rugulate, 8‒12 × 5‒8 μm………………………Dimelaena radiata
Thallus with marginal lobes c. 1 mm wide; apothecia sessile, epruinose………………………Diploicia canescens
24(22) Ascospores submuriform to muriform………………………25
Ascospores 1-septate………………………27
25(24) Thallus green; ascospores muriform………………………Rhizocarpon geographicum
Thallus white or grey; ascospores submuriform, with a few longitudinal septa (Diplotomma spp.)………………………26
26(25) Thallus K+ red (red crystals in section)………………………Diplotomma chlorophaeum
Thallus K−………………………Diplotomma alboatrum
27(24) Ascospores double-walled, walls variously thickened………………………28
Ascospore wall of uniform thickness………………………33
28(27) Ascospores Physconia-type………………………29
Ascospores of different type………………………31
29(28) Thallus rimose, whitish to brown; ascospores 10‒15 × 6·5‒8·5 μm………………………Amandinea pelidna
Thallus areolate to bullate to bullate-subsquamulose………………………30
30(29) Conidia filiform, 15–30 μm long; thallus areolate to bullate, pale to dark brown………………………Amandinea coniops
Conidia bacilliform, 5–6 μm long; thallus flat, bullate to bullate-subsquamulose, whitish to ochraceous………………………Buellia dispersa
31(28) Ascospores Mischoblastia-type………………………Rinodina oxydata
Ascospores of different type………………………32
32(31) Thallus C+ red; ascospores between Physcia and Milvina-type………………………Rinodina luridescens
Thallus C−; ascospores Pachysporaria-type………………………Rinodina beccariana var. lavicola
33(27) Apothecia immersed………………………34
Apothecia adnate to sessile………………………35
34(33) Thallus K+ red (norstictic acid); ascospores 12‒18 × 6‒10(‒12) μm………………………Buellia aethalea
Thallus K+ yellow (atranorin); ascospores 10‒13 × 5·0‒7·0(‒8·5) μm………………………Buellia stellulata
35(33) Thallus K+ red, C+ red or C+ orange………………………36
Thallus K− or K+ yellow and C−………………………39
36(35) Thallus K+ red (norstictic acid)………………………37
Thallus K− or K+ yellow (different chemistry)………………………38
37(36) Thallus containing xanthones (UV+ orange); conidia 6‒7 × 1·0‒1·2 μm………………………Buellia indissimilis
Thallus without xanthones (UV−, but with atranorin); conidia 9‒13 × 0·8‒1·0 μm………………………Buellia subdisciformis
38(36) Thallus rimose cracked, yellow-grey, C+ red, UV− (gyrophoric acid)………………………Buellia saxorum
Thallus areolate, white to pale yellow-grey, C+ orange, UV+ orange (xanthones)………………………Buellia ocellata
39(35) Hymenium inspersed with oil droplets………………………Buellia leptoclinoides
Hymenium clear………………………40
40(39) Thallus delimited by a dark fimbriate prothallus, K+ sordid yellow-brown, KC+ brownish orange or KC+ briefly pinkish………………………Buellia tesserata
Thallus not delimited by a dark fimbriate prothallus; thalline reactions different………………………41
41(40) Conidia bacilliform, up to 8 μm long………………………42
Conidia filiform, up to 30 μm long………………………Amandinea punctata
42(41) Thallus forming rosettes, well delimited by a pale prothallus; apothecia adnate, rarely sessile, up to 0·5 mm diam; conidia 2·5‒4·0 × 1·0‒1·5 μm………………………Buellia caloplacivora
Thallus not forming rosettes; apothecia cryptolecanorine to adnate, up to 0·7 mm diam.; conidia 4‒6 × 1 μm Buellia spuria
Author ORCIDs
Alan M. Fryday: 0000-0002-5310-9232
We are grateful to Maarten Brand for the loan of his specimens, and also thank Måns Svensson (UPS) for checking the identity of the lectotype of Lecidea valentior.
