KEYS TO STERILE, CRUSTOSE SAXICOLOUS AND TERRICOLOUS LICHENS OCCURRING IN THE BRITISH ISLES

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1 Lichenologist 29(4): (1997) KEYS TO STERILE, CRUSTOSE SAXICOLOUS AND TERRICOLOUS LICHENS OCCURRING IN THE BRITISH ISLES Alan FRYDAY* and Brian COPPINS Abstract: A set of artificial keys is presented to all those crustose lichens (except most species of Lepraria and Leproloma) which commonly occur without fruiting bodies on rock or soil in the British Isles. A number of predominantly corticolous species that occasionally also occur on rocks are included, as well as several undescribed but well-understood entities The British Lichen Society Introduction Saxicolous lichens are generally perceived to be difficult and, consequently, have received far less attention than corticolous species. However, this is largely a self-perpetuating problem as the main reason they remain difficult is because they are little studied. Their difficulty is primarily a consequence of two factors: (1) they often grow in areas little visited by lichenologists (e.g. uplands and mountains) and are, therefore, less often collected (2) because of the nature of their substrata it is more difficult to obtain good specimens for examination. This situation is even more pronounced when it comes to sterile species. Sterile corticolous lichens have been the subject of comprehensive studies in Scandinavia (Tønsberg 1992) and Central Europe (Schreiner & Hafellner 1992), and The Lichen Flora of Great Britain and Ireland (Purvis et al. 1992) provided a key to those sterile species that grow on bark or wood. In contrast there are no studies devoted to sterile saxicolous lichens and no recent key that attempts to treat all the known species in an area. Every attempt has been made to make these keys as complete as possible. Over 200 taxa are included, which is significantly more than the 156 sterile corticolous species in Purvis et al. (1992). We have included all the sterile saxicolous and terricolous crustose lichens occurring in Britain and Ireland that are known to us. This includes a number of taxa that are sorediate morphs of fertile species (i.e. Fuscidea cyathoides var. sorediata and Lecanora rupicola var. efflorens), which, although not known to us without apothecia, may be expected to occur in a sterile state. A number of squamulose species are also included, especially where these are either usually sterile and/or closely adpressed (e.g. Agonimia tristicula, Arthrorhaphis alpina, Hypocenomyce scalaris). Among the squamulose genera not included are Acarospora, *Department of Landscape, University of Sheffield, Sheffield S10 2TN, UK. Present Address: 110 Eastbourne Road, Darlington, Co. Durham DL1 4ER, UK. Royal Botanic Garden, Inverleith Row, Edinburgh EH3 5LR, UK /97/ $25.00/0/li The British Lichen Society

2 302 THE LICHENOLOGIST Vol. 29 Catapyrenium, Cladonia, Leptogium, Pannaria, Parmeliella, Psora, Squamarina and Toninia. Additional taxa are to be expected. Some of these will be new national records or even taxa new to science, but others will be saxicolous occurrences of normally corticolous or lignicolous taxa. Known examples of the last are mostly found in woodland habitats, for example Lecanora jamesii, Loxospora elatina, and Mycoblastus caesius, or on lowland siliceous stonework, for example Pertusaria coccodes and P. hemisphaerica. Also included are a number of undescribed taxa; most of which will be formally described in taxonomic papers currently in preparation. The majority of the species of the genera Lepraria and Leproloma are not included. This is because: (1) their identification is often extremely difficult without resorting to thin-layer chromatography (TLC) (2) a key to these two genera has recently been published (Orange 1995) and this should be consulted, along with the present Key 1, for all leprose species. Leproloma membranaceum and the species of the Lepraria caesioalba group (which includes the granular form of Lepraria cacuminum) are included because the lobed thallus of the former and the well-developed, granular thallus of the latter could result in them being mistaken for belonging to other genera. Where a species is known to occur as more than one chemotype, all but the very rarest are included. However, it is not possible to allow for every eventuality and the possibility of unusual ecology and chemistry should always be borne in mind. We have also allowed for morphological variations (and interpretations). For instance, several species are included in both the key for non-corticate species and the appropriate partially corticate key. It should also be stressed that the keys are intended for well-developed thalli of species that usually occur without fruiting bodies; many specimens of usually fertile species with a poorly developed thallus or lacking ascomata will remain indeterminate. It should also be mentioned that these keys are not intended as a self-sufficient means of identification. When a specimen has been keyed-out it should be checked against a more detailed description of the species, preferably in Purvis et al. (1992), which these keys are intended to supplement. For the most part the keys use only thallus morphology and chemical spot tests as principal characters, although occasionally the colour reaction under UV light is required. Ecological and distributional information is sometimes included when this helps to increase the certainty of a determination but this should always be treated with at least the same caution as other characters. The type of photobiont present in the lichen is also used in the keys. This can be of two main types; cyanobacteria (blue green algae) and Chlorophyceae (green algae). Many of the genera of cyanobacteria found in lichens are illustrated in Purvis et al. (1992: 669), although they are often deformed and hard to identify when lichenized. Among the Chlorophyceae two genera, in particular, are used as characters in the keys. These are Trentepohlia, which contains a distinctive orange pigment when fresh and when old can usually be distinguished by its larger more rectangular cells arranged in filaments, and

3 1997 Sterile crustose keys Fryday & Coppins 303 Chlorella, which divides by binary fission resulting in cells often being arranged in twos and fours. Also occasionally used are Stichococcus, which has short fragmenting filaments of small ovoid-rectangular cells, and micareoid cells consisting of small spherical units 4 7 μm in diameter. Soredia or other similar structures (e.g. blastidia or goniocysts) are described as farinose when the majority are no more than 40 μm diam, or granular when the majority exceed 40 μm diam. With a 10 hand lens, individual farinose soredia are scarcely discernible, whereas individual granular soredia can be easily resolved. Chemical spot-test reactions are often best carried out microscopically by mounting a section of the specimen to be tested on a slide and flooding the preparation with the appropriate chemical. This applies particularly to reactions with C, especially on those species with a dark thallus (e.g. Rimularia furvella and Placynthiella icmalea. Spot tests can also be carried out by extracting the lichen substances onto filter paper with acetone as follows: (1) position fragments of the lichen at the centre of the filter paper (2) add several drops of acetone to the specimen, allowing each drop to dry before applying the next (3) remove the fragments of lichen (4) using a needle point or the end of a matchstick carry out spot tests to the resultant ring of extract on the filter paper. As with extracting material for TLC, care must be taken to avoid contamination since a few granules of a Lepraria, for example, can lead to confusing results. The reaction given with PD is that for the freshly dissolved reagent in methylated spirits. The reaction of atranorin with PD may cause some confusion. This is represented in the keys as PD or PD+ faint yellow but the colour often develops over a period of about 30 seconds to produce a quite distinct colour. A true PD+ yellow reaction develops within 5 10 seconds of application of the reagent. In cases of doubt the reagent should be tested on a specimen of a common lichen known to contain atranorin (e.g. Lecanora chlarotera, Physcia spp., Platismatia glauca, Tephromela atra). The presence of confluentic acid (used as a character in Key 4) can be detected, without resorting to TLC, as described by Fryday (1992). It is important to remember that Key 2 is for all those species that give a positive spot-test reaction with C, regardless of whether they are sorediate or not. Nomenclature mainly follows Purvis et al. (1994), but additional taxa or recently adopted name changes are listed in the Appendix. Informal, provisional names are given between single quotation marks.

4 304 THE LICHENOLOGIST Vol. 29 THE KEYS Synopsis 1 Thallus with at least some corticate areas Thallus completely non-corticate or leprose Key 1 2(1) Thallus and soredia C, KC Thallus and/or soredia C+ (or KC+) red, orange or yellow Key 2 3(2) Thallus with soredia or blastidia Thallus with neither soredia nor blastidia (3) Thallus or soredia either K+ or PD Key 3 Thallus and soredia with all spot-test reactions negative.. Key 4 5(3) Thallus either K+ or PD Key 5 Thallus with all spot-test reactions negative Key 6 KEY 1 Sterile, saxicolous and terricolous, crustose lichens with a noncorticate or leprose thallus 1 Thallus C+ red (or at least KC+ reddish orange) or C+ persistent orange Thallus C (1) C+ persistent orange (xanthones present). Thallus yellow-green to green (occasionally straw coloured) when fresh Thallus C+ or KC+ red, often fleeting (xanthones absent). Thallus grey or brown (rarely green-brown) (2) Thallus of farinose soredia, ( 50) μm diam Thallus of finely granular to granular blastidia or soredia, often >40 μm diam. with yellowish brown or grey-ochre tinge (usnic acid absent) (3) Thallus green-grey to straw coloured (usnic acid absent); surface soredia often brown, grey or flecked blue-grey Lecidella scabra Thallus composed of yellowish green soredia (usnic acid present) Lecanora expallens 5(3) Thallus of granular blastidia, μm diam Lecidella meiococca Thallus of finely granular soredia, μm diam Pyrrhospora quernea

5 1997 Sterile crustose keys Fryday & Coppins 305 6(2) Thallus of smooth, grey granules, forming irregular rosettes; granules >100 μm diam. PD+ yellow (alectorialic acid). Usually in exposed situations Lepraria neglecta Thallus sorediate or isidiate; if granular than not grey. PD (gyrophoric acid) (6) Thallus leprose, grey to blue-grey, continuous to rimose. On vertical, usually copper-rich, rocks Psilolechia leprosa Thallus isidiate or sorediate, rarely leprose or granular; brown or greenish brown, never grey (7) Thallus dark brown to black, the surface minutely isidioid or granular Thallus brown or greenish brown, composed of soft, sorediose granules (8) Isidia simple, Photobiont cells 6 12 μm diam. On exposed siliceous rocks Rimularia furvella Isidia branched. Photobiont cells 5 9 μm diam. On damp, shaded rocks or soil Placynthiella icmalea 10(8) Thallus usually with some areoles. On damp siliceous rocks and stones Trapelia obtegens Thallus of soft sorediose granules. On soil, bryophytes, plant debris, etc Placynthiella dasaea 11(1) Photobiont cyanobacteria (Nostoc) Photobiont Chlorophyceae (green algae) (11) Thalline granules pale blue-grey to grey-blue-black Moelleropsis nebulosa Thalline granules olivaceous to dull grey-brown Moelleropsis humida A number of small crustose-granular Leptogium spp. may key out here. They can be distinguished from Moelleropsis by their usually well-developed cellular cortex. A key to these species is given by Jørgensen (1994). 13(11) Photobiont with orange pigment (Trentepohlia) Photobiont without orange pigment (13) Thallus widely spreading or of orbicular patches, thin, pinkish; UV. On calcareous rocks, (N+)... Belonia nidarosiensis Thallus greyish white, tinged pink, forming small, thick cushions; UV+ ice-blue (lepraric acid). On acidic rocks (N ) Lecanactis latebrarum 15(13) Thallus yellow, yellow-green or green Thallus grey, brown or black

6 306 THE LICHENOLOGIST Vol (15) Thallus K+ purple Thallus K+ yellow or K (16) Thallus with distinct, shallow marginal lobes and white medulla.. Leproplaca xantholyta Thallus without marginal lobes (17) On acidic rocks. Blue-grey patches, K, UV+ white (divaricatic acid) also often present Lepraria incana On calcareous rocks or over bryophytes. completely yellow or yellow-brown (18) Thallus brownish yellow. Often over bryophytes Leproplaca chrysodeta Thallus yellow or greenish yellow. Usually directly on rocks.... Caloplaca citrina 20(16) Thallus K+ yellow (atranorin) Thallus K (atranorin absent) (20) White, arachnoid prothallus usually present. Centre of thallus completely leprose; soredia uniformly yellow (usnic acid) Haematomma ochroleucum var. ochroleucum Prothallus absent. Thallus non-corticate with discrete, blue-grey flecked soredia. Usually coastal Lecania baeomma 22(20) Thallus of goniocysts, mm diam., without pigments. Photobiont micareoid. Usually on bryophytes but occasionally directly on siliceous rocks Micarea prasina Thallus leprose (non-corticate). Coloured by yellow, green or bright yellow-green pigments. Photobiont not micareoid (22) Bright green or yellow-green (pulvinic acid derivatives); usnic acid absent Thallus yellow to yellow green (usnic acid). Over bryophytes on siliceous rocks, usually in crevices Lecanora sp. 24(23) Thallus rarely more than 1 2 cm diam. composed of small areoles which break down into granular soredia. Rhizocarpic acid present Arthrorhaphis citrinella Thallus more widely spreading, completely leprose (24) On shaded rocks, walls etc., often in underhangs. Thallus yellowgreen On vertical rock-faces. Thallus bright, citrine yellow (25) Photobiont usually trebouxioid. Rhizocarpic acid present. Thallus granules <0 1 mm Psilolechia lucida Photobiont usually Stichococcus. Pulvinic and vulpinic acids present Chaenotheca furfuracea

7 1997 Sterile crustose keys Fryday & Coppins (25) Thallus granules >0 1 mm. Calycin and vulpinic acid present... Chrysothrix chlorina Thallus granules mm. Calycin or pinastric acid present.. Chrysothrix candelaris 28(15) Thallus brown, covered with minute, fragile blastidia. Usually on copper-rich rocks Rhizocarpon furfurosum Thallus cream to grey (28) Thallus of smooth, grey granules forming rosettes in exposed situations Thallus otherwise (29) Thallus PD+ deep yellow or red Thallus PD or faint yellow (atranorin) (30) Thallus PD+ red (fumarprotocetraric acid). Lepraria caesioalba Thallus PD+ yellow (psoromic acid).. Lepraria cf. caesioalba 32(30) Porphyrilic acid by TLC Lepraria cacuminum Porphyrilic acid absent Lepraria borealis The granular form of Lepraria cacuminum (which appears to be much rarer than the leprose form) can be separated from L. borealis only by TLC. 33(29) Thallus with distinct lobes, forming irregular rosettes. PD+ orange (pannaric acid) Leproloma membranaceum Thallus not lobed; prothallus or a marginal corticate area often present (33) Surface soredia blue-grey Soredia whitish to pale grey throughout (34) Soredia farinose, <40 μm diam. On sheltered rocks Lecania baeomma Soredia granular, c μm diam. On exposed rocks Tephromela grumosa 36(34) Thallus coarsely granular; granules c μm diam. Terricolous Icmadophila ericetorum Thallus farinose to granular; granules mostly <100 μm diam. Saxicolous (sometimes over bryophytes) (36) Thallus generally rather thick and areolate but obscured by farinose soredia, mostly μm diam.; thallus usually delimited by a conspicuous white, arachnoid prothallus; PD or PD+ faint yellow (atranorin and porphyrilic acid). Usually directly on rock Haematomma ochroleucum var. porphyrium

8 308 THE LICHENOLOGIST Vol. 29 Thallus not or scarcely areolate, mostly formed of granular soredia, μm diam.; thallus not or only rarely delimited by a distinct white prothallus; PD+ red, occasionally PD or PD+ faint yellow (atranorin, zeorin, fumarprotocetraric acid). Usually overgrowing bryophytes Catillaria pulverea KEY 2 Sterile, saxicolous and terricolous, crustose lichens with C positive spot-test reaction (NOTE: All lichens with a C+ spot-test reaction are included in this key, regardless of whether or not they are sorediate.) 1 Thallus and/or soredia C+ persistent orange (xanthones) Thallus and/or soredia C+ yellow or fleetingly red (1) Thallus with thin isidia Pertusaria flavocorallina Thallus with soredia or proliferating granules (2) Thallus PD+ orange. On basic rocks Pertusaria amarescens Thallus PD (3) Soredia granular (>40 μm diam.) Soredia farinose (<40 μm diam.) (4) Thallus composed of soredia-like granules (blastidia), μm diam Lecidella meiococca Thallus continuous or areolate. Soredia smaller, in discrete soralia (5) Thallus cream to brownish yellow, continuous-areolate. Soredia μm diam Ochrolechia inversa Thallus yellow-green, smooth and cracked to coarsely warted; usually glossy. Soredia granular ( μm diam.) Pertusaria flavicans 7(4) Thallus grey-green (usnic acid absent), thin to granular-tuberculate; surface soredia often brown, grey or flecked blue-grey Lecidella scabra Thallus yellowish green (usnic acid); effuse, granular, rarely cracked areolate; soralia concolorous, excavate or diffuse Lecanora expallens 8(1) Photobiont with orange pigment (Trentepohlia) Photobiont without orange pigment (8) Thallus C ; with numerous stalked, white-pruinose pycnidia the tips of which are C+ red. Over bryophytes Lecanactis abietina Thallus C+ red; without stalked pycnidia. Directly on rock.. 10

9 1997 Sterile crustose keys Fryday & Coppins (9) Thallus thin, brownish Opegrapha gyrocarpa Thallus usually thick, white-grey (10) Thallus tartareous; soredia μm diam. Medulla UV. Contains lecanoric acid only Arthonia endlicheri Thallus thick (occasionally thin and dispersed when on siliceous rocks); soredia μm diam. Medulla UV+ glaucous or (rarely) yellow. Contains lecanoric acid and erythrin Dirina massiliensis f. sorediata 12(8) Thallus distinctly lobed, placodioid or squamulose Thallus without lobes (12) Thallus composed of greyish green, olive-brown to dark brown discrete, ascending squamules (to 1 2 mm diam.), the margins slightly upturned with white, farinose soredia Hypocenomyce scalaris Thallus crustose with marginal lobes. If squamules discrete then never ascending (13) Squamulose; marginal lobes >0 2 mm wide Placodioid; marginal lobes <0 15 mm wide (14) Squamules distinct >0 5 mm wide. Often with coarse isidiate soredia. Terricolous, usually among rocks. Trapeliopsis wallrothii Squamules indistinct <0 4 mm wide. Never sorediate or isidiate. Usually saxicolous, rarely terricolous..... Trapelia involuta 16(14) Thallus matt, or shiny only at lobe tips, without depressions. Soralia often eroded, rarely black. Cephalodia usually distinctly lobate. 5-O-methylhiascic acid absent (TLC)..... Placopsis gelida Thallus shiny, often with small depressions. Soralia at the level of the thallus, usually blackish, sometimes capitate and greenish. Cephalodia usually not distinctly lobate. 5-O-methylhiascic acid present (TLC).... Placopsis lambii [see Moberg & Carlin (1996)] 17(12) Thallus developing thin, spine-like extensions. Usually montane.. Ochrolechia frigida Thallus otherwise (17) Thallus without soralia. Isidia, papillae, pycnidia or apothecia initials present Thallus with soralia or sorediose patches (18) Thallus completely isidiate, isidia obscuring the thallus Thallus with scattered papillae, pycnidia or apothecia initials (19) Thallus and isidia white, pale grey or creamish Thallus and isidia brown (occasionally greenish)

10 310 THE LICHENOLOGIST Vol (20) Thallus indistinct. Isidia white to pale grey, often darkened at the apices, not eroding. All parts PD+ red (fumarprotocetraric acid). Pertusaria oculata Thallus distinct. Isidia usually soft and eroding. All parts PD.. Ochrolechia subviridis 22(20) Isidia simple. Photobiont cells 6 12 μm diam. On exposed siliceous rocks Rimularia furvella Isidia branched. Photobiont cells 5 9 μm diam. On damp, shaded rocks Placynthiella icmalea 23(19) Thallus with papillae. Saxicolous Thallus with pycnidia or apothecia initials (23) Thallus thin, grey to pinkish brown. Papillae mm diam.. Rimularia intercedens Thallus thick and tartareous (up to 3 mm), pale to dark grey. Papillae larger Ochrolechia tartarea 25(23) Thallus C, of convex orange areoles, C+ red apothecia initials or pycnidia present Trapelia mooreana Thallus C+ red (25) Saxicolous. Thallus well-developed, cracked-areolate; whitish grey to grey-brown. Photobiont not micareoid. Conidia 7 10 μm long. Lecidea fuscoatra Usually terricolous, rarely saxicolous. Thallus of globose areoles, green-grey to yellowish. Photobiont micareoid. Conidia longer 27 27(26) Conidia flexuose, μm long Micarea cinerea Conidia curved or sigmoid, μm long Micarea peliocarpa 28(18) Thallus C+ yellow, KC+ yellow; thin, white-grey, smooth. Soralia often excavate and in lines, becoming crowded and confluent.. Ochrolechia microstictoides Thallus C+ red, KC+ red (28) Thallus or soredia PD+ yellow, orange or red Thallus and soredia PD or PD+ faint yellow (29) Thallus of greyish granules Thallus not of greyish granules (30) Thallus or sorediose patches PD+ red (argopsin) Micarea leprosula Thallus or sorediose patches PD+ yellow (alectorialic acid) (31) Granules usually forming irregular rosettes, not eroding to form sorediose patches Lepraria neglecta Granules usually forming an effuse crust; granules fragile and often eroding to form sorediose patches.... Micaria submilliaria

11 1997 Sterile crustose keys Fryday & Coppins (30) Growing directly on rock, soredia greenish to brown Growing on bryophytes or soil; soredia grey-white to creamish (33) Soredia greenish, K or K+ faintly yellow (alectorialic acid). Photobiont Chlorella-like Fuscidea praeruptorum Soredia dark brown, K+ red (norstictic acid), forming acicular crystals (microscope). Photobiont trebouxioid Rimularia furvella 35(33) Soralia discrete, formed by the apices of papillate granules bursting open. Alectorialic and barbatolic acids present Pertusaria geminipara Soredia widely spreading, formed by eroding thallus. Gyrophoric acid and unidentified substance present Ochrolechia inaequatula 36(29) Thallus without discrete soralia Thallus with discrete soralia (36) Thallus white to pale grey, well-developed. Soralia effuse formed from abrading isidia Ochrolechia subviridis Thallus black, brown or greenish brown (37) Thallus dark brown to black, the surface minutely isidioid or granular. On exposed siliceous rocks.... Rimularia furvella Thallus brown or greenish brown, composed of soft, sorediose granules (38) Thallus usually partly areolate. On damp rocks and stones..... Trapelia obtegens Thallus completely non-areolate. On soil, bryophytes, plant debris, etc Placynthiella dasaea 40(36) Saxicolous Terricolous or bryophilous (40) Thallus thin or poorly developed Thallus thick and clearly visible (41) Thallus K+ yellow (atranorin); on siliceous pebbles and flints... Rinodina aspersa Thallus K (atranorin absent) (42) Soralia green, punctiform; photobiont micareoid Micarea coppinsii Soralia pale buff to ochraceous brown, not punctiform; photobiont Chlorella-like Trapelia obtegens

12 312 THE LICHENOLOGIST Vol (41) Thallus pale grey-green to dark chocolate brown, soredia pale ochreyellow to pale yellow-green. UV+ bluish white Ropalospora hibernica Thallus and soredia otherwise (44) Thallus of irregular grey-green convex areoles; soralia grey-green to blue-green Trapeliopsis flexuosa Thallus and soredia without green or blue-green colour (45) Thallus tinged pink; margin composed of discrete, effigurate areoles. Photobiont Chlorella-like.... Trapelia placodioides Thallus white or grey; margin entire. Photobiont trebouxioid (46) Soredia white to blue-white; C+ carmine red (lecanoric acid), gyrophoric acid absent Thallus grey, soredia cream to grey-green; C+ orange-red, (gyrophoric acid) (Ochrolechia androgyna s. lat.) 49 48(47) Centre of thallus regularly cracked and forming discrete areoles. Soralia mm diam., usually tuberculate with a raised thalline rim; soredia (62 ) ( 220) μm diam Pertusaria lactea Centre of thallus irregularly rimose, not forming discrete areoles. Soralia mm diam., rarely tuberculate (except when young); soredia μm.... Pertusaria hemisphaerica 49(47) Thallus usually very thick (up to 3 mm), grey-white; often with numerous pinkish papillae..o. androgyna B sensu Tønsberg (sorediate morph of Ochrolechia tartarea) Thallus thinner, creamy-white; without papillae Ochrolechia androgyna A sensu Tønsberg 50(40) Thallus and soralia without green or yellowish colouration; thallus white-grey, soralia cream coloured. Ochrolechia androgyna A Thallus and/or soralia with green or yellowish colouration (50) Thallus with irregular orange-red, K+ purple patches Trapeliopsis pseudogranulosa Thallus without orange-red patches (51) Soralia grey-green to dark green, often tinged blue-green Trapeliopsis flexuosa Soralia whitish to brownish yellow, sometimes tinged blue-green.. Trapeliopsis granulosa Poorly developed or shaded specimens of these two species are often impossible to separate. They are described in detail by Coppins & James (1984).

13 1997 Sterile crustose keys Fryday & Coppins 313 KEY 3 Sterile, saxicolous and terricolous, crustose lichens with soralia or blastidia and C but K+ or PD+ spot-test reactions 1 Thallus and/or soredia K+ purple (anthraquinone pigments); orange or yellow Thallus K+ red or yellow, or K (anthraquinone pigments absent); not orange, rarely yellow (1) Thallus whitish-grey, K ; soredia yellow to orange-brown, K+ purple. On siliceous rocks, often in underhangs Pyrrhospora rubiginans Thallus and soredia yellow to orange, K+ purple (2) Thallus crustose, without marginal lobes Thallus with marginal lobes (3) Thallus with discrete soralia. On vertical, acidic or slightly basic montane rock faces caloplaca obliterans Thallus with effuse soralia. Widespread; usually on strongly basic rocks and walls caloplaca citrina 5(3) Soralia bright yellow, lighter than thallus..caloplaca cirrochroa Soralia orange, concolorous with thallus...caloplace decipiens 6(1) Thallus and/or soredia K+ red (norstictic acid), acicular crystals formed (microscope) Thallus and soredia K+ yellow or orange or K, acicular crystals not formed (6) Thallus with crowded, globose, isidia-like papillae which leave eroded, granular-sorediate patches....pertusaria lactescens Thallus without isidia or papillae; soredia present (7) Thallus grey; soralia discrete, soredia concolorous and granularisidiate (?A. simoensis) or yellow-green and farinose (?A. grisea). Aspicilia grisea aggr. Thallus white or cream, soralia becoming confluent (8) Thallus thick, rimose-cracked-areolate. Soralia convex, arising from wide, low warts; at first discrete, later becoming confluent. Soredia coarsely-granular, creamish grey. Saxicolous Pertusaria excludens Thallus thin, continuous or sparingly cracked. Soralia very irregular, shallow, ulcerous to effuse. Soredia fine-powdery to coarselygranular, often greenish. Saxicolous, often over bryophytes... Phlyctis argena

14 314 THE LICHENOLOGIST Vol (6) Soralia KC+ violet Soralia KC (10) Soralia not formed on thalline warts......pertusaria amara Soralia formed by the breaking down of thalline warts (11) Thallus forming compact cushions of sorediate, warted papillae.. Pertusaria amara f. pulvinata Papillae more scattered, only occasionally breaking down to form granular soredia Pertusaria melanochlora 13(10) Thallus distinctly lobed or squamulose Thallus without lobes, sometimes of dispersed areoles (13) Thallus with radiating lobes. PD..... Diploicia canescens Thallus without radiating lobes. PD+ orange or red (14) Thallus composed of congested squamules. PD+ orange (stictic, norstictic acids) Baeomyces rufus Thallus of dispersed, narrow lobes. PD+ red (argopsin)..... Solenopsora vulturiensis 16(13) Thallus or soredia PD+ red, orange or distinct yellow Thallus and soredia PD or faintly yellow (atranorin) (16) Thallus with discrete soralia, at least in part; sometimes coalescing when older Thallus with effuse soredia, corticate areas confined to the thallus margin (17) Thallus orange, brown or bright green Thallus white or grey; sometimes becoming yellow or orange due to oxidization if on iron-rich rocks (18) Thallus green; soredia bright yellow-green (pulvinic acid derivatives; stictic acid absent) Thallus orange or brown; soredia blue-black or brown (stictic acid; pulvinic acid derivatives absent) (19) Soralia arising from the margins of the areoles.lecanora subaurea Soralia arising from the centre of the areoles..lecanora epanora 21(19) Thallus of discrete brown areoles on a powdery black hypothallus that produces thallospores. Soredia brown, abrading creamish.. Protoparmelia nephaea Thallus yellow-orange, oxydated; continuous. Soredia blueblack

15 1997 Sterile crustose keys Fryday & Coppins (21) Thallus ochre to yellow-orange; areoles often dispersed, uneven to strongly convex. On metal-rich rocks, often with Acarospora sinopica Miriquidica atrofulva Thallus yellow-orange, cracked-areolate; areoles flat. Usually on damp siliceous rocks Porpidia ochrolemma 23(18) Thallus PD+ red (fumarprotocetraric acid) Thallus PD+ orange or yellow (fumarprotocetraric acid absent) 25 24(23) Thallus pale grey-fawn to dark grey, usually with a strong brown tinge (dove coloured) K+ brownish yellow (succinprotocetraric and protocetraric acids absent). Soralia mm diam. rounded to convex, pale yellow-brown to greenish Fuscidea cyathoides var. sorediata Thallus pale to dark grey, without brownish tinge, K+ yellow-red (succinprotocetraric and protocetraric acids). Soralia to 1 0 mm diam., flat to slightly convex, white... Pertusaria aspergilla 25(23) PD+ yellow or yellow-orange (psoromic or thamnolic acids).. 26 PD+ orange (stictic acid) (25) Soralia tuberculate, punctiform, mm diam., soredia blueblack. On exposed montane rocks. K (psoromic acid present). Miriquidica nigroleprosa Soralia convex, often becoming confluent, mm diam., soralia pale yellow to yellow-grey. On rocks in woodlands. K+ bright yellow (thamnolic acid) Loxospora elatina 27(25) Thallus composed of prostrate, dorsiventral pseudopodetia; upper surface with grey phyllocladia with darker centres Stereocaulon vesuvianum var. symphycheileoides Thallus crustose, continuous to areolate (27) Thallus of flat to convex areoles, often with darker centres. Usually cracked with green soralia arising from the cracks. Soredia becoming blue-grey or brownish when old. Atranorin present Soredia not arising from cracks in the areoles; white, grey or blue-grey, never green. Atranorin absent (28) Areoles usually forming a continuous crust Stereocaulon tornense Areoles usually dispersed Stereocaulon plicatile Stereocaulon plicatile (Leighton) Fryday & Coppins differs from S. tornense in having muriform spores. In the absence of apothecia it is not possible to separate these two species with any degree of certainty. 30(28) Thallus sub-continuous to scurfy and indistinct Porpidia soredizodes Thallus well developed

16 316 THE LICHENOLOGIST Vol (30) Thallus of convex areoles, white to pale grey. Soredia blue-grey. Cephalodia absent. On exposed rocks Porpidia aff. glaucophaea Thallus cracked areolate to verrucose. Soredia cream or grey. Cephalodia present or absent (31) Thallus grey. Soredia concolorous and granular-isidiate (?A. simoensis) or yellow-green and farinose (?A. grisea). Cephalodia absent. On exposed rocks and walls Aspicilia grisea aggr. Thallus creamy white. Soredia concolorous. Cephalodia often present. On shaded, often damp rocks Coccotrema citrinescens 33(17) Thallus brown. Densely covered with minute, fragile blastidia... Rhizocarpon furfurosum Thallus white, grey or green. Without blastidia (33) Thallus thin, smooth; grey-white to glaucous. Cortex usually visible only at margin. Atranorin and zeorin by TLC Catillaria pulverea Thallus thick, warted, dark grey-green. Atranorin and zeorin absent. Lecanora conizaeoides 35(16) Thallus with discrete soralia, at least in part; sometimes coalescing when older Thallus with effuse soredia, corticate area confined to the thallus margin (35) Thallus usually of dispersed areoles, each areole having a dark centre (similar to the phyllocladia of Sterocaulon vesuvianum). Bluish-green soredia arising from the edge of each areole and remaining discrete Stereocaulon leucophaeopsis Areoles without darkened centre (36) Soredia distinctly blue-grey throughout Soredia whitish-green to yellow, sometimes with blue-grey flecks 41 38(37) Soredia diffuse, formed from the break-down of the thallus surface. Appearing almost leprose except for the thallus edge. Soredia granular, μm diam Tephromela grumosa Soredia in discrete soralia, sometimes becoming confluent in places (38) Soralia convex to hemispherical. Thallus continuous, granular, of dispersed to aggregated warted areoles. Prothallus when present, white or bluish Lecanora caesiosora Soralia plane to excavate

17 1997 Sterile crustose keys Fryday & Coppins (39) Soredia blue-black, μm diam.; soralia orbicular at first becoming irregular Lecidea pycnocarpa f. sorediata Soredia grey-blue, μm diam.; soralia irregular from the beginning, often forming on the edge of the areoles Lecanora pannonica 41(37) On limestone (or other basic rocks), thallus forming circular patches, surface rough to warted Lecanora campestris subsp. dolomitica On siliceous rocks (41) Red pigment present in medulla. Thallus thick, smooth. Soralia creamy yellow..... Mycoblastus sanguinarius f. leprosus Red pigment not present in medulla (42) Thallus yellow. Soralia concolorous, developing from the edges of the areoles, usually forming lines, later becoming confluent. Usually on exposed rocks Lecanora orosthea Thallus grey. Soralia not developing from the edges of the areoles. Usually on shaded rocks (43) Thallus film-like with low grey warts. Soralia at first punctiform, bursting from thalline warts, later coalescing; bright yellow (usnic and planaic acids) Mycoblastus alpinus Soralia not bursting from thalline warts; creamy white to pale yellow (planaic acid absent) (44) Thallus thin, continuous, smooth to granular, 2 3 cm diam. Prothallus, when present, black. Soralia circular, convex, up to 1 mm diam. Soredia farinose, pale yellow. Atranorin, usnic acid and 2 -O-methylsulphurellin present..... Lecanora jamesii Thallus thicker, often of convex granules. Usnic acid and 2 -Omethylsulphurellin absent (45) Soredia μm diam., whitish blue, hemispherical. Atranorin and α-collatolic acid present... Tephromela pertusarioides [probably a sorediate morph of T. atra] Soredia smaller, occasionally aggregating into granules (consoredia). α-collatolic acid absent (46) Thallus continuous, granular, of dispersed to aggregated warted areoles. Prothallus when present, white or bluish Lecanora caesiosora Thallus cracked-areolate often thick and uneven, areoles flat to slightly convex; surface smooth. Prothallus black Lecanora rupicola var. efflorens 48(35) Thallus white to grey; soredia blue-grey, darker than thallus.. 49 Thallus and soredia concolorous

18 318 THE LICHENOLOGIST Vol (48) Thallus white to yellow-white, indeterminate; completely dissolved into blue-grey speckled, farinose soredia (20 25 μm diam.). Contains atranorin, chloratranorin and gangaleoidin. On shaded rocks, predominantly coastal Lecania baeomma Thallus pale-grey, corticate, sometimes with blue-black prothallus. Soredia blue-grey, granular, μm diam. Contains atranorin and unidentified substance. On exposed rocks Tephromela grumosa 50(48) Thallus not or scarcely areolate, mostly formed of granular soredia, μm diam.; prothallus rarely evident. Zeorin by TLC... Catillaria pulverea Thallus generally rather thick and areolate but obscured by farinose soredia, mostly μm diam.; usually delimited by a white arachnoid prothallus. Zeorin absent (50) Thallus whitish to pale grey, without yellowish tinge (usnic acid absent).... Haematomma ochroleucum var. porphyrium Thallus pale yellow to yellow-green (usnic acid present) Haematomma ochroleucum var. ochroleucum KEY 4 Sterile, saxicolous and terricolous, crustose lichens with soralia or blastidia with all spot-test reactions negative 1 Photobiont Trentepohlia Photobiont without orange pigments (1) Corticate areas confined to margin, centre of thallus completely dissolved in thick, creamy soredia; UV+ ice-blue Schismatomma umbrinum Thallus mostly corticate, soralia discrete, scattered over the thallus; UV (2) Thallus lilac to pinkish grey; soralia concolorous, discrete to slightly confluent. Often covering relatively large areas Schismatomma decolorans Thallus grey-green to brown with discrete soralia scattered over the thallus (3) Thallus dark chocolate-brown tinged lilac, soralia dark brown to lilac. Usually with a blackish delimiting prothallus and often forming mosaics with Opegrapha gyrocarpa. Confluentic acid and/or 2 -O-methylmicrophyllinic acid present Enterographa zonata Thallus grey-green to red-brown, widespreading and effuse, soralia bright orange when fresh. No lichen substances present..... Opegrapha multipuncta

19 1997 Sterile crustose keys Fryday & Coppins 319 5(1) Terricolous, or over bryophytes Saxicolous, directly on rocks (5) Areoles granular, convex or spherical Areoles flat or thallus membrane-like (6) Thallus of dull grey-green granules (goniocysts), <0 1 mm diam. Photobiont micareoid Micaria prasina Thallus of bright yellow-green granules, mm diam. Photobiont not micareoid Arthrorhaphis citrinella 8(6) Thallus of small grey squamules, mm wide, with ascending, grey-green sorediate apices.... Trapeliopsis glaucolepidea Thallus thin, membrane-like; covered with discrete, yellow-green soralia Trapeliopsis gelatinosa Trapeliopsis pertrenata, which differs from T. glaucolepidea in having smaller squamules ( mm wide), has so far been recorded only from lignum. The very rare T. aeneofusca is doubtfully distinct from T. gelatinosa, differing only in the colour of the epithecium. The two are indistinguishable when sterile. 9(5) On basic substrata (N+) On acidic substrata (N ) (9) Thallus white to pale grey, obscurely placodioid or of dispersed areoles Thallus green; continuous, without marginal lobes. In damp, shaded habitats (10) Thallus obscurely placodioid, lobes broad and shallow; continuously scurfy Caloplaca teicholyta Thallus of dispersed areoles, with discrete black soralia emerging from the sides of the areoles Aspicilia moenium 12(10) Areoles dispersed, soredia greyish green, UV : Upland/montane, on strongly basic rock (limestone or mica-schist) Polyblastia efflorescens Areoles confluent, soredia yellowish-green, UV+ pink or orange (coronat on). Lowland/upland, on weakly basic rock faces, walls and monuments Bacidia viridifarinosa 13(9) Thallus yellow, green or pale grey to dark grey/black Thallus orange or brown (13) Soralia yellow (usnic acid or pulvinic acid derivatives) Soralia green, white, grey or bluish (usnic acid and pulvinic acid derivatives absent) (14) Soralia developing from the edges of the areoles Soralia arising from the centre of each areole

20 320 THE LICHENOLOGIST Vol (15) Thallus grey to grey-green, thick, areoles usually convex occasionally flatter and subsquamulose; often dispersed. Soredia not forming lines, usually remaining discrete Lecanora handelii Thallus yellow-green, thinner, areoles plane, confluent. Soredia usually forming lines, later becoming confluent Lecanora orosthea 17(15) Thallus thick, areoles rounded and warted with entire margins; bright yellow-green (pulvinic acid derivatives present) Lecanora epanora Thallus thinner, areoles flattened, subsquamulose, margins often crenulate, greenish grey, yellowish green or greenish brown (usnic acid present) Lecanora soralifera 18(14) Medulla I+ blue. Soralia punctiform, tuberculate, surface soredia blue-grey. Confluentic acid present... Porpidia tuberculosa Medulla I (18) Thallus UV+ pink or orange (coronaton), with effuse yellowishgreen soralia Bacidia viridifarinosa Thallus UV ; medulla UV+ white or UV (19) Medulla UV+ white (divaricatic or perlatolic acids) Medulla UV (divaricatic and perlatolic acids absent) (20) Soredia pale green to blue-grey. Photobiont trebouxioid. Perlatolic acid by TLC Mycoblastus caesius Soredia white to brown. Photobiont Chlorella-like. Divaricatic acid by TLC (21) Thallus of thin, pale-grey, dispersed areoles on a black hypothallus. Soredia concolorous..... Fuscidea gothoburgensis Thallus continuous, pale grey to brownish grey. Soralia soon becoming confluent, cream, often becoming brownish Fuscidea recensa 23(20) Thallus blue to dark grey/black Thallus grey to greenish grey (23) Thallus blue to dark grey; pigmented hyphae grey, K+ violet [microscope]. Thallus surface continuously blasidiate. Miriquidic acid absent by TLC Rinodina pityrea Thallus dark grey to black; hyphae not K+ violet. Soralia punctiform. Miriquidic acid present by TLC Lecidea liljenstroemii 25(23) Thallus of grey, subsquamulose or convex areoles. Soralia concolorous, arising from the edge of each areole but often becoming confluent Lecanora handelii

21 1997 Sterile crustose keys Fryday & Coppins 321 Thallus otherwise, soredia not arising from the edge of each areole (25) Thallus and/or soredia greenish or yellowish Thallus and soredia grey (26) Thallus with discrete, yellow-green soralia; soredia farinose. Atranorin and 2-O-methylsulphurellin by TLC Lecanora jamesii Thallus continuously blastidiate. Lichen substances absent by TLC (27) Thallus thin, effuse, scurfy, cracked areolate..lecania erysibe Thallus thick, determinate, coarsely rimose-cracked Lecania coeruleorubella 29(26) Thallus waxy, often with zoned margin or delimiting prothallus. Soralia large, 1 4 mm diam., often becoming confluent or soredia effuse Thallus thick, without zoned margin or delimiting prothallus. Soralia <1 mm diam. remaining discrete (29) Thallus pale grey-blue to dark bluish grey; granular-papillate becoming granular sorediate. Often with a dark green-grey delimiting prothallus. Usually on maritime rocks, never overgrowing bryophytes. Aspicilin by TLC Aspicilia leprosescens Thallus pale grey to dark greenish grey, often zoned at the margin. On siliceous or slightly basic rocks and walls, sometimes overgrowing bryophytes. Aspicilin absent; other fatty acids present by TLC (30) Soralia typically concave and marginate; soredia granular..... Pertusaria albescens var. albescens Soralia less well-defined; soredia becoming granular-coralloid... Pertusaria albescens var. corallina 32(29) Thallus glaucous, continuous to cracked-areolate. Soralia usually irregular in shape, sometimes arising along cracks in the thallus. On flushed, or damp, siliceous or slightly basic rocks. Confluentic acid absent Porpidia glaucophaea Thallus pale-grey, composed of convex areoles. Soralia regularly rounded, blue-grey. On exposed siliceous rocks. Confluentic acid present Porpidia confluenta ad int. 33(13) Thallus orange with discrete, blue-grey soralia Porpidia melinodes Thallus brown with concolorous soredia

22 322 THE LICHENOLOGIST Vol (33) Soredia arising from cracks in the thallus. On basic rocks Soredia initially in punctiform sorelia that soon become confluent. Not arising from cracks in the thallus. On siliceous rocks.... Ropalospora lugubris subsp. sorediata ad int. 35(34) Soredia isidiate-granular Soredia farinose Thelidium papulare f. sorediatum 36(35) Thallus areolate to subsquamulose, pale brown to olive green; areoles mm wide... Verrucaria macrostoma f. furfuracea Thallus areolate, dark brown, green-black or black; areoles mm wide.... Verrucaria nigrescens (sorediate morph) KEY 5 Sterile, saxicolous and terricolous, crustose lichens with C but either K+ or PD+ spot test reactions and without soralia. Isidia or pycnida often present NOTE: All those lichens with a partly corticate thallus and a positive spot-test reaction with C are included in Key 2. 1 Thallus orange or yellow Thallus grey, green, brown or black (1) Thallus K+ purple (anthraquinone pigments). Restricted to calcareous substrata or maritime rocks Thallus K (pulvinic acid derivatives). Over soil, bryophytes or Baeomyces rufus in acidic habitats (2) Terricolous Saxicolous (3) Thallus placodioid, marginal lobes clearly differentiated. S. and E. England Fulgensia fulgens Thallus warty-scaly, marginal lobes poorly differentiated at most. At high altitude in the Scottish Highlands.. Fulgensia bracteata 5(3) Thallus placodioid Thallus crustose or minutely squamulose (5) Lobes up to 6 mm long Caloplaca verruculifera Lobes up to 2( 3) mm long Caloplaca granulosa 7(5) Thallus crustose; isidia coralloid often forming a continuous crust Caloplaca littorea Thallus minutely squamulose; isidia spherical, often in clusters.. Caloplaca britannica