a revision of the species of the rhizocarpon hochstetteri ... · rhizocarpon discoense is shown to...

Lichenologist 34(6): 451–477 (2002)doi:10.1006/lich.2002.0416, available online at http://www.idealibrary.com on

A revision of the species of the Rhizocarpon hochstetteri groupoccurring in the British Isles

Alan M. FRYDAY

Abstract: Rhizocarpon hochstetteri s. str. is shown to be an upland/montane species with relativelylarge ascospores. The name Rhizocarpon infernulum is resurrected for the species with smallerascospores previously included within R. hochstetteri, but which is probably more closely related toR. cinereovirens. Lectotypes are chosen for a number of taxa, including R. cinereovirens andR. infernulum, and descriptions provided for two new taxa with small hyaline, 1-septate ascospores:R. caesium, which occurs on damp, mildly basic rocks in oceanic areas, and R. infernulum f. sylvaticumoccurring on siliceous rocks in damp deciduous woodlands. All these taxa are known also from NorthAmerica. Rhizocarpon discoense is shown to be a distinct species, not a synonym of R. cinereovirens. Thedifferent ascospore dimensions reported for R. hochstetteri by British and European authors are shownto be due to confusion between R. hochstetteri and R. polycarpum. A number of morphologicalcharacters are evaluated regarding their relevance to species separation in Rhizocarpon and the nameMacrocarpa-green is proposed for the olivaceous pigment present in most species of Rhizocarpon andPorpidia. A key is provided for the species of Rhizocarpon with hyaline, 1-septate ascospores.

� 2002 The British Lichen Society. Published by Elsevier Science Ltd. All rights reserved.

Key words: British Isles, North America, Rhizocarpon.

A. M. Fryday: Herbarium, Department of PlantBiology, Michigan State University, East Lansing,MI 48824-1312, USA. E-mail: [email protected].

Introduction

It has been realized for some years that twotaxa were involved in British specimens ofRhizocarpon hochstetteri (Körb.) Vain. One ofthese occurs on damp, siliceous rocks inoceanic woodlands, has a thin thallus, sessileapothecia with a thin, raised persistentmargin, and small ascospores, whereas theother occurs on exposed upland/montanerocks, has a thicker, grey-brown thallus,more innate, flatter apothecia and largerascospores. Other collections with smallascospores from less humid, more exposedhabitats have a thicker thallus and moreinnate apothecia but are clearly conspecificwith the small-spored taxon. Previously(Fryday 1996, 1997), I believed the name

0024–2829/02/060451+27 $35.00/0 � 2002 The British Liche

R. hochstetteri to be applicable to the small-spored species and suggested that R.‘colludens’ may be the correct name for thelarge-spored species. However, examinationof the holotype of R. hochstetteri, which wasnot previously available for study, has shownit to be a specimen of the large-sporedspecies with an atypically thin thallus. Rhizo-carpon infernulum (Nyl.) Lynge is, therefore,resurrected from the synonymy of R. hoch-stetteri for the small-spored species, and the f.sylvaticum Fryday proposed for the distinc-tive form that typically occurs in dampwoodlands. A third taxon, also with smallascospores but larger, flatter apothecia and avividly aeruginose epihymenium, has alsobeen identified from mildly basic rocks inwestern areas of the British Isles (Fryday1996, 1997) for which the name R. caesiumFryday is proposed.

The description of R. hochstetteri given byPurvis et al. (1992) is a combination of

n Society. Published by Elsevier Science Ltd. All rights reserved.

452 THE LICHENOLOGIST Vol. 34

elements of all these taxa (Fryday 1996).Due to the confusion surrounding R. hoch-stetteri, a full description of the species isprovided along with descriptions for R.infernulum, the closely related R. cinereovirens(Müll. Arg.) Vain., and the new taxa.

Materials and Methods

Observations are based on material collected by theauthor from the British Isles and specimens held in BM,CANL, E, MICH, MIN and MSC and the personalherbaria of J. Buschbom, S. P. Chambers, V. J.Giavarini and E. Lay. Critical material was obtained onloan from BM, C, G, GB, H, L, TUR and UPS. Allspecimens collected by the author are held in hispersonal herbarium unless otherwise cited.

Microscopic descriptions are based on observationsmade of hand-cut sections mounted in water and 10%KOH. All ascospore measurements were made in 10%KOH and exclude the perispore.

Thin-layer chromatography (TLC) follows themethods of White & James (1985). Nomenclature forepihymenial pigments follows Meyer & Printzen(2000), using 10% KOH and 50% HNO3. However, Ido not consider the greenish pigment in the epihy-menium of most of the taxa discussed here to be thesame as that present in Schaereria cinereorufa (Schaer.)Th. Fr., and prefer to use the name Macrocarpa-greenfor this pigment (see below).

The Species

Rhizocarpon hochstetteri (Körb.) Vain.Acta Soc. Fauna Fl. Fenn. 53: 280 (1922).—Catillariahochstetteri Körb., Parerga Lich.: 195, (1861); type:Germany, Würtemberg, Esslingen, an granitishenFeldsteinen in bergigten Gegenden, Hochstetter (L—holotype!).

Lecidea atroalba var. applanata Fr., Summa Veg.Scand., sect 1: 116 (1846).—Rhizocarpon applanatum(Fr.) Th. Fr., Lich. Scand. 2: 618 (1874).—Lecideaapplanata (Fr.) Leight. Lich. Fl. Brit., ed. 3: 327 (1879);type: not designated.

Lecidea atroalba var. chlorospora Nyl., Bot. Notiser1853: 96 (1853).—Lecidea colludens Nyl., Flora 53:38 (1870), nomen novum.—Buellia colludens (Nyl.)Arnold, Flora 53: 479 (1870).—Buellia chlorospora(Nyl.) Hellb., Nerikes Lafflora: 104 (1871).—Lecideahochstetteri var. colludens (Nyl.) Vain., Medd. Soc. Faun.Fl. Fenn. 10: 132 (1883).—Catillaria colludens (Nyl.)Jatta, Flora Ital. Crypt. 3: 41 (1911).—Rhizocarponhochstetteri f. colludens (Nyl.) Vain., Acta Soc. Faun. Fl.Fenn. 53(1): 333 (1922).—Rhizocarpon massalongii f.colludens (Nyl.) Zahlbr., Cat. Lich. Univ. 4: 336

(1927); type: Finland, ‘Holmiae’, 1852, W. Nylander(H-NYL 10047—lectotype).

Rhizocarpon crenulatum H. Magn., Bot. Notiser 1951:75 (1951); type: Sweden, Jämtland, Are, Storlien, in theravine, 600 m, 24 vii 1950, A.H. Magnusson 22110(UPS—holotype!).

Rhizocarpon hochstetteri f. incrassatum (‘incrassata’)(Vain.) Vain., Acta Soc. Faun. Fl. Fenn. 53(1): 334(1922).—Lecidea hochstetteri f. incrassata Vain., Medd.Soc. Faun. Fl. Fenn. 10: 131 (1883); type: Finland,Lapponia inarensis, Inari, Hammastunturit, E. Vainio22014 (TUR-V 23794—lectotype selected here).

(Fig. 1)

Thallus grey-brown to red-brown, moder-ately thick to thick (0·1–0·35 mm), cracked-areolate; areoles flat to convex, 0·2–1·0 mmdiam. Photobiont chlorococcoid, cells (10–)12–15(–18) �m diam.

Apothecia frequent, black, lecideine, flat toslightly convex, 0·6–1·0(–1·2) mm diam.,sessile when well developed, or innateamong areoles; exciple persistent but oftenpoorly formed. Hymenium 95–150 �m tall,hyaline, I+ blue; epihymenium usuallywith aeruginose to blue-black pigment(Macrocarpa-green; K�, N+ red). Para-physoids branched and anastomosing, 2·5–3·0 �m wide (swelling at apex to 3·5 �m),with sharply delimited brown (Atra-brown) cap. Asci c. 85–100�30–35 �m,Rhizocarpon-type. Ascospores hyaline becom-ing brown when over mature, halonate, 8 perascus, 1-septate, 21·0–25·0(–28·0)�(8·5–)10·0–12·0 �m. Hypothecium dark brown(Arnoldiana-brown). Excipulum of radiating,dark brown hyphae.

Conidiomata not seen.

Chemistry. C�, K� or K+ yellow, Pd�or Pd+ orange. No substances or stictic aciddetected by TLC. Medulla I�.

Nomenclature. There are several othernames that have been used for this species:

Buellia chlorospora (Nyl.) Hellb.Vainio (1922: 332) cited H–NYL 10047

and H–NYL 10060 as ‘specimen orig.’ Ihave not seen H–NYL 10047, but H–NYL10060 is typical material of R. hochstetteriwith several pigmented ascospores, a normal

2002 The Rhizocarpon hochstetteri group—Fryday 453

F. 1. Rhizocarpon hochstetteri s. str., thallus and apothecia A, alpine form with stictic acid (Fryday 1358); B,upland form lacking stictic acid (Fryday 2285). Scales; A=1 mm; B=2 mm.

character in the taxon. H–NYL 10047 wasselected by Brodo (Inoue 1997) as thelectotype of Lecidea colludens Nyl., which

Nylander introduced as a nomen novum forLecidea atroalba var. chlorospora Nyl. (seebelow).


Buellia colludens (Nyl.) Arnold

Nylander (1870—not 1871 as stated byZahlbruckner 1926) introduced this namefor Lecidea atroalba var. chlorospora, which hedescribes as ‘nomen rejiciendum’. It is,therefore, also a synonym of R. hochstetteri.

There are six specimens under this namein H–NYL. Two (H–NYL 10047 & 10060)were originally named L. atroalba var.chlorospora (see above) and of the other four(all from the British Isles), three (H–NYL10045, 10067, 10071) are referable to R.infernulum, and the fourth (H–NYL 10064)to R. hochstetteri.

Rhizocarpon applanatum (Fr.) Th. Fr.

This taxon is usually considered a syno-nym of R. hochstetteri (e.g. Zahlbruckner1926, Thomson 1967). I have not seenoriginal material but the description given byTh. Fries (apothecia 1·0–1·2 mm diam.,ascospores 16–29�6–13 �m) clearly sup-ports this placement.

Rhizocarpon concretum (Ach.) Zahlbr.

Lecidea atro-alba � [var.] concreta Ach., K. svenskaVetensk. Akad. Handl. 1808: 233 (1808).—Lecidea atro-alba � [var.] concreta ‘Wahlenb.’, Fl. lapp.: 471(1812).—Lecidea confervoides � [var.] concreta (Ach.)Schaer., Lich. Helv. Spic., sect. 3: 128 (1828).—Catillaria concreta (Ach.) A. Massal., Ric. Lich. Crost.:79 (1852).—Catillaria concreta (Ach.) Körb. Syst. Lich.German. 232 (1855).—Rhizocarpon concretum (Ach.)Zahlbr., Wiss. Mitt. Bosnien und Hergov. 3: 608(1895).—Rhizocarpon concretum (Ach.) Elenkin, Lich.Fl. Ross. 3: 126 (1904); type: ad saxa in montosisSveciae (UPS–ACH—lectotype selected here). [Note:all the above combinations apart from the basionymand the last are nomina sed non planta.]

The basionym of Rhizocarpon concretum(Lecidea atro-alba var. concreta Ach.) isvalidly published, and the epithet is validat specific rank since the publication ofCatillaria concreta (Ach.) A. Massal. in 1852.

The original material of this taxon wasapparently collected by Wahlenberg (Svecia.Lapponica: Rupes), but first describedby Acharius (1808) and only later byWahlenberg (1812). Although Wahlenbergmade no direct reference to Acharius’ namein his treatment, and the descriptions are

very different, he did refer to Lecideaatro-alba (L.) Ach. under the specificepithet, and so must have been aware ofAcharius’ use of the infra-specific epithet afew lines below. Also, Acharius (1814) givesL. atro-alba var. concreta Wahlenb. as a syno-nym of L. atro-alba var. concreta Ach., so itseems clear that Wahlenberg did not intendto introduce a new name, and L. atro-alba var. concreta Wahlenb. is a homotypicsynonym of L. atro-alba var. concreta Ach.

Schaerer (1828) included both Lecideaatro-alba Ach. and L. atro-alba Wahlenb. assynonyms of L. confervoides (DC.) Schaer.,but cited only L. atro-alba var. concretaWahlenb. under his new combination L.confervoides var. concreta (Ach.) Schaer. Thiscitation was followed by both Massalongo(1852) and Körber (1855, 1861) when,independently, they made the new combi-nation Catillaria concreta for different speciesin Schaerer’s exsiccatae Lich. Helv. no 177,and Acharius’ use of the name was not‘rediscovered’ until Th. Fries (1860) in-cluded it in the synonymy of Rhizocarpongeminatum Körb. However, as R. geminatumhas large, pigmented, eumuriform asco-spores and Massalongo clearly illustrated aspecies with small, 1–2-celled, hyaline as-cospores (loc. cit., fig. 160), Massalongo ob-viously had a very different species in mindfrom that described by Acharius. Körber(1861) recognizes three different speciesin Schaerer’s exsiccate: ‘C. concreta sensuKörber’, ‘C. concreta sensu Massalongo’, and‘‘a form of Rhizocarpon petraeum’’ [= R.obscuratum aggr.]. He distinguishes C. con-creta sensu Massalongo from his own by itssessile apothecia and very small, initially non-septate, finally light brownish ascospores, andintroduced for it the nomen novum Catillariamassalongoi Körb. (see below).

The specimens of Lich. Helv. no 177, inSchaerer’s herbarium in G, consist of fivepackets, although one contains two pieces ofrock, making a total of six specimens. Threehave hyaline, eumuriform ascospores andbelong to Rhizocarpon reductum Th. Fr. (syn.R. obscuratum auct.), one has hyaline,submuriform ascospores, a K+ purple epi-hymenium, and an I+ blue medulla and is


R. distinctum Th. Fr., and two have simpleascospores, Fuscidea-type asci and areFuscidea lygaea (Ach.) V. Wirth & Vezda.Inspection of other examples of the no. 177from Schaerer’s exsiccatae (in BM, E, & L)revealed the same mix of species with theaddition of Buellia aethalea (Ach.) Th. Fr.None have ascospores that are 2-celled andhyaline, or pigmented and eumuriform. Ofthe four specimens labelled Catillariaconcreta in Körber’s herbarium in L, one isR. polycarpum (Hepp) Th. Fr., and three,including one from his ‘Typenherbar’, are R.cinereovirens, leaving no doubt that, as pre-viously noted by Vainio (1922), this latterspecies is C. concreta sensu Körber. Of thespecies known to be included in Schaerer’sLich. Helv. no 177, the description of C.concreta sensu Massalongo best fits Fuscidealygaea, because that species has sessileapothecia and over-mature ascospores oftenbecome pale brown and occasionally de-velop a median septum. Although it is inter-esting to know what taxon Schaerer,Massalongo, and Körber considered the epi-thet ‘concreta’ to refer to, the identity of theirspecimens is irrelevant to the correct use ofthe name, because this is linked to Lecideaatro-alba var. concreta Ach. and it is theidentity of Acharius’ specimens that isimportant.

There are three specimens of Lecidea atro-alba var. concreta in BM–ACH (no. 73), onein UPS–ACH, and none in H–ACH. Of theBM–ACH specimens, which are annotatedjust ‘� concreta’, one (on the left of the card)has hyaline, two-celled ascospores measur-ing 27–29�16–18 �m, a K+ purple epihy-menium and is referable to R. polycarpum,whereas the other two have large, dark-pigmented, strongly muriform ascosporesand are referable to R. disporum (Nägeli exHepp) Müll. Arg. or R. geminatum, whichare separated only by the number of sporesper ascus. Of these two specimens, one (inthe centre of the card) has single-spored asci,and a thallus containing stictic acid (K+yellow), whereas the other specimen (on theright of the card) has a thallus lacking sticticacid (K�), and the number of spores perascus in the same apothecium is variable (a

phenomenon noted in these two taxa byprevious workers, for example Lynge 1932;Thomson 1967). The single specimen inUPS–ACH, which has been annotated(?by Th. Fries) ‘Herb. Agrel’ [Agrelius,Acharius’ son-in-law] ‘Ex herb. Achariano’‘Lapponica: Wahlenberg’ and ‘=Rhizoc.geminatum’, has the same characters as thaton the right of the card in BM–ACH andappears to be part of the same collection, butis larger. It is tempting to select the specimenof R. polycarpum in BM–ACH as thelectotype, thus supporting the concept ofMassalongo and Körber of a species withtwo-celled ascospores. However, the asco-spore dimensions given by Massalongo(9·0�2·44 �m) and those of R. cinereovirens(13·5–16·0�7·0–8·5 �m) are much lessthan those of the specimen in BM–ACH,and so Massalongo and Körber evidently didnot have this specimen in mind when theymade their combinations into Catillaria. AsLecidea atro-alba var. concreta Ach. is usuallyconsidered to be a synonym of Rhizocarpongeminatum (e.g. Fries 1860; Santesson1993) or R. disporum (e.g. Lynge 1932;Thomson 1967), and this also appears tohave been Acharius’ intention, I here selectthe specimen in UPS–ACH as the lectotypeof Lecidea atro-alba var. concreta, because thisis the only specimen documented as havingbeen collected by Wahlenberg in ‘Sveciae’(Acharius 1810).

Unfortunately, the validation (as a nomensed non planta) of the epithet ‘concreta’ atspecies rank by Massalongo in 1852, gives itprecedence over both Rhizocarpon disporum(1853) and R. geminatum (1855), as well asR. cinereovirens (1868), R. distinctum (1876),R. polycarpum (1879), and R. reductum(1874). Vainio (1922) realized this andincluded R. geminatum in the synonymy ofR. concretum (Ach.) Elenk., but this usagehas not been taken up and the name hasfallen out of use. Consequently, a proposalto reject Lecidea atro-alba var. concreta Ach.,to preserve current usage, is in preparation.

Rhizocarpon crenulatum H. Magn.

As stated by Timdal & Holtan-Hartwig(1988), this is typical, although poorly


developed, R. hochstetteri. A similar collec-tion, with no apparent thallus, was collectedin Glen Lochay, mid-Perthshire, Scotland(see below).

Rhizocarpon massalongoi (‘massalongi’)(Körb.) Malme

Catillaria massalongoi Körb., Parerga lich.: 195(1861).—Rhizocarpon massalongoi (Körb.) Malme,Lich. suec. exs. fasc. 5, no. 124 (1909) nomen sed nonplanta; type: Schaerer Lich. Helv. no 177 (L—lectotypeselected here)

Rhizocarpon massalongoi (originally spelt‘massalongi’, and also later spelt ‘massalongii’,but see ICBN Rec. 60C.1), has often beenlinked with Rhizocarpon hochstetteri, and waspreviously used in preference to it (e.g.Zahlbruckner 1926). Also, when Vainio(1922) made the new combination R. hoch-stetteri (Körb.) Vain. he included R. massal-ongoi as a synonym of R. hochstetteri f.incrassatum (‘incrassata’) (Vain.) Vain. (seebelow), and the single specimen of Malme’sexsiccati no. 124 that I have seen (MIN) isreferable to R. infernulum f. sylvaticum (seebelow), which was previously included in R.hochstetteri. The name has also sometimes(e.g. Hafellner & Türk 2001; Nimis 1993;Santesson 1993) been referred to the R.obscuratum group, presumably because theseauthors saw one of the many specimens ofSchaerer’s Lich Helv. no. 177 that belong tothis taxon (see above, under Rhizocarponconcretum). However, Lynge (1932), citingSchade (in litt.), says ‘‘the type plant ofKoerber’s ‘Catillaria massalongii’ in herb.Leiden . . . is a Biatora, with simple smallspores, about 7·5�5 �m’’. Schade appearsnot to have published this observation, how-ever, as he makes no mention of Rhizocarponin any of his publications from 1931 to 1933,except Schade (1933) in which he uses thename R. hochstetteri without any reference toR. massalongoi.

In the protologue of C. massalongoi,Körber cited ‘Catillaria concreta Massal. Ric.79’, such that it might seem that C. massal-ongoi is a superfluous name for C. concreta(Ach.) A. Massal. However, Körber clearlystates that he is introducing C. massalongoi asa replacement name for C. concreta sensu

Massalongo, which is a very different speciesfrom C. concreta (Ach.) A. Massal. (seeabove under R . concretum). Catillaria massa-longoi, therefore, refers to that species repre-sented in Lich. Helv. no. 177 that mostclosely matches Massalongo’s description ofC. concreta.

The single specimen of Lich. Helv. no 177in L, where Körber’s herbarium is located,consists of a mixed collection of Rhizocarponreductum, Buellia aethalea and Fuscidealygaea. The last species was annotated bySchade in February 1931 ‘Biatora sp.’, andfrom Massalongo’s and Körber’s descrip-tions it is clear also that this is the species forwhich Massalongo made the new combi-nation Catillaria concreta, and for whichKörber introduced the nomen novumCatillaria massalongoi. Consequently, I heredesignate the specimen of Fuscidea lygaea inLich. Helv. no 177 in L the lectotype ofCatillaria massalongoi.

Remarks. In the British Isles Rhizocarponhochstetteri is a species of exposed siliceousrocks in upland/montane situations where itis widespread and frequent.

Timdal & Holtan-Hartwig (1988) recog-nized two chemical races of R. hochstetteri,with or without stictic acid, suggestingthat acid-deficient specimens had thinnerareolae, a lower hymenium and possiblysmaller ascospores. Of the 28 specimens ofR. hochstetteri from the British Isles exam-ined in this study, nine contained sticticacid. These were all from high altitudes(over 900 m) and had a thick red-brownthallus with innate, immarginate apothecia(Fig. 1A), and hymenium and spore dimen-sions towards the upper end of the range.Conversely, most specimens lacking sticticacid tended to occur at lower altitudes,and had a grey-brown thallus with sessileapothecia (Fig. 1B). Previously (Fryday1996, 2001), I tentatively recognized thestictic acid containing race as var. rufoatrum(of R. ‘colludens’). However, a population ofR. hochstetteri from the Queen CharlotteIslands (British Columbia, Canada) alsocontains stictic acid but has the thallusmorphology and ecology of the typical


specimens from the British Isles. Therefore,I now consider the recognition of the sticticacid-containing strain as a distinct taxonuntenable.

Vainio (1883) described the new taxonLecidea hochstetteri f. incrassata Vain., andlater (Vainio 1922) he made the new com-bination, Rhizocarpon hochstetteri f. incras-satum (‘incrassata’) (Vain.) Vain. The threecollections cited in the protologue are inTUR-V named Rhizocarpon applanatum var.incrassata, although this new combinationand status does not appear to have beenpublished. In the protologue, Vainiodescribes his new taxon as ‘‘thallusrufescens’’ and this, combined with the epi-thet ‘incrassatum’ (=thickened), suggests theentity discussed above as ‘var. rufoatrum’. Ofthe three specimens in TUR-V, one doeshave a thallus containing stictic acid (K+yellow, Pd+ orange) and composed of thickconvex areoles, but these are grey, notred-brown. However, as this collection‘Lapponia inarensis’ most closely matchesVainio’s description, and is also the only onecited in both Vainio 1883 and 1922, I heredesignate it the lectotype. If this entityis recognized at the rank of forma, thenVainio’s name is available and must be used.It should also be considered if the entity isrecognized at a different rank. The other twocollections in TUR-V have a thallus com-posed of flat, grey-brown areoles lackingstictic acid and are typical R. hochstetteri.

Rhizocarpon hochstetteri usually has a blue-black epihymenium (Macrocarpa-green),although the paraphysoid tips are brown(Atra-brown), and correspondingly contigu-ous paraphysoids (see below). However, onecollection (R. Munro, Glen Doll) has ahyaline epihymenium and readily separatingparaphysoid tips.

Other lichens associated with R. hochstet-teri in the British Isles include Leprariacaesioalba, Frutidella caesioatra, Ionaspisodora, Miriquidica complanata, M. griseoatra,Porpidia tuberculosa, Rhizocarpon geographi-cum aggr., Rhizocarpon lavatum, R. poly-carpum and Stereocaulon tornense.

The collections from New Zealand havesomewhat smaller ascospores than Northern

Hemisphere collections, with which they areotherwise in good agreement. This phenom-enon has been observed in other lichenspecies (Smith & Øvstedal 1994; Fryday2000a) and deserves further investigation.

Rhizocarpon hochstetteri s. str. appears tooccupy a rather isolated position within thegenus. All the other species considered herehave small, persistently hyaline ascospores,whereas in R. hochstetteri they are both largerand tend to become somewhat pigmentedwhen mature. In some respects, R. hochstet-teri appears more closely related to the R.polycarpum/R. richardii group, although itlacks the amyloid (I+ blue) medulla of thosetwo species, or to species with pigmentedascospores, for example R. badioatrum(Flörke ex Spreng.)Th. Fr. or R. copelandii(Körb.) Th. Fr. s. lat.

Selected specimens examined. Great Britain: Wales:V.C. 49, Caernarfonshire: Gwastadnant, CwmGlas-bach, 23/6156, 325 m, on top of low flat boulder,1994, Fryday 5747. England: V.C. 70, Cumberland:Pillar, 35/1712, 900 m, acid rocks, iv 1988, Fryday s.n.;ibid., Yewbarrow, Wastdale, 35/1607, 300 m acidrock, April 1988, Fryday s.n. Scotland: V.C. 88, Mid-Perthshire: Ben Lawers, top, vii 1864, I. Carroll (BM);ibid., gully, 1869, J. Stirton (BM) [on granite!]; Meallnan Tarmachan, N-E crags, 27/5839, 950 m, mica-schist rocks near late snow-lie, 7 vii 1989, Fryday s.n.;Glen Dochart, Ledcharrie, 27/50228, 175 m, acidboulder, x 1989, Fryday s.n.; Ben Lawers range, GlenRoro, 27/6141, 900 m, top of low mica-schist rock,1991, Fryday 2120; Beinn Heasgarnich, Creag nah-Achlarich, 27/4238, 750 m, top of flat acidic rock,1991, Fryday 2159; Beinn Heasgarnich, Creag namBodach, 27/4437, 650 m, top of acidic boulder, 1991,Fryday 2191, Beinn Cheathaich, 27/4432, 925 m,acidic boulder on summit, 1991, Fryday 2278. V.C. 96,East Inverness-shire: Cairngorm, Ciste Mhearad, 38/0104, 1075 m, granite boulder by late snow bed, 1995,Fryday 6259. V.C. 97, West Inverness-shire: AonachMór, N of bealach, 27/1972, 1100 m, schistose cragsnear cornice snow bed, 1990, Fryday [1336], O. L.Gilbert & V. J. Giavarini; Ben Nevis, summit plateau,27/1671, 1340 m, top of crags affected by cornice snowbed, 1990, Fryday [1355], O. L. Gilbert & V. J.Giavarini; Aonach Mór, 27/1972, 1150 m, acidic rockabove late snow patch, 1990, Fryday 1225; ibid., Coirean Lochain, 27/1973, 1050 m, acidic rocks below latesnow patch, 1990, Fryday 1311 & 1314. V.C. 98,Argyll Main: Dalmally, Beinn a’ Chochuill, 27/1132,850 m, exposed granite boulder, 1991, Fryday [2251]& R. Leishman. V.C. 104, North Ebudes: Isle of Skye,Trotternish, The Storr, 18/4954, 700 m, exposed acidboulder, 1990, Fryday 1283. V.C. 105, West Ross:Beinn Dearg, 28/2581, 1000 m, rocks above late snow


bed, 1995, Fryday 6228 & 6242.—Germany: seecitation of holotype.—Norway: Nordland: Gildeskål, bythe road c. 3·5 km W of Forstranda, 67�00�N, 13�53�E,20 m, on shaded rock in humid deciduous forest 1990,R. Haugan H1622 (O).—Canada: British Columbia:Queen Charlotte Islands, 53�14�N 132�34�W, GrahamIsland, Gudal Bay, N shore, on shoreline outcrops, inlower aerohaline, 1967, I. M. Brodo [10190], M. P.Shchepanek & W. B. Schofield (CANL); ibid., MoresbyIsland, 52�38�N 131�46�W, head of Bigsby Inlet; S sideof first lake W of inlet, along cascade, and in Tsuga-Thuja forest, on rocks at lakeside, 1971, I. M. Brodo[17829], P.Y. Wong & W.B. Schofield (CANL). NovaScotia: Shelburne County, Tobeatic Wilderness Area,44�03�N 65�32�W, on large boulder along stream, 1999,D. Ladd 21582 (hb. Ladd).—USA: Massachusetts,Berkshire County, Adams Township, Mt GraylockReservation, 42�38·23�N 73�9·96�W, 1035 m, just be-low summit on exposed rocks along roadcut, 1995, D.Ladd 18624, (hb. Ladd). Missouri: Iron County, E slopeof Royal George, 380 m, oak-hickory forest with graniteoutcrops and boulders, 1988, R.C. Harris 21782(NY).—New Zealand: South Island, Southland: Sub-alpine scrub in basin at E portal of Homer Tunnel, LakeCounty. 1973, H. A. Imshaug 57995 (MSC); ibid.,Arthur’s Pass National Park, region of scattered scruband bogs above the forest on s. side of road to Arthur’sPass, 1971, H. A. Imshaug 47876 (MSC); ibid., R. C.Harris 6095 (MSC).

F. 2. Rhizocarpon caesium (Fryday 5708) thallus and apothecia. Scale=2 mm.

Rhizocarpon caesium Fryday sp. nov.Thallus caesius interdum leviter oxydatus, laevis,continuus vel rimosus; ascomata plana vel leviter con-vexa, �innata vel sessilia, grandia 0·8–1·3(–2·0) mmdiametro; excipulum proprium vulgo exclusum, ubivisibile crassiusculum sed vix elevatum; hymenium110–120 �m altum; epihymenium cyaneum; paraphys-oides parce ramosae et anastomosantes, c. 2·5 �m latae,apicibus vix dilatatae, sed apice omni pileum delimi-tatum cyaneum instructo, autem versus excipulumpileis brunnescentibus; ascosporae hyalinae, 1-septatae,13·5–15·0(–18·0)�7–8·5 �m.

Typus: Caledonia, V.C. 104, North Ebudes, Isleof Skye, Cuithearaing [Quiraing], 18/4569, 250 m,slightly basic basalt crags, 8 June 1991, A. M. Fryday2448 (E—holotypus).

(Figs 2, 3, 4A)

Thallus rimose to cracked areolate, blue-grey occasionally slightly oxidated; areoles0·2–0·5 mm diam., flat. Photobiont chloro-coccoid, cells (10–)12–15(–18) �m diam.

Apothecia black, lecideine, flat and innateto slightly convex, 0·8–1·3(–2·0) mm diam.;proper margin (if apparent) thick but barely


raised. Hymenium hyaline, I+ blue, 110–120 �m tall; epihymenium bright aerugi-nose. Paraphysoids c. 2·5 �m thick, scarcelyswelling at apex (to 3·0 �m) with sharplydelimited bright blue cap (Cinereorufa-green; K+ brighter, N+ red) becomingbrown (Atra-brown) towards exciple, spar-ingly branched and anastomosing. Asci c.70�30 �m, Rhizocarpon-type. Ascosporeshyaline, halonate, 1-septate, 8 per ascus,13·5–15·0(–18·0)�7–8·5 �m, often slightlyconstricted at septum. Hypothecium darkbrown (Arnoldiana-brown). Excipulum usu-ally thin, of radiating hyphae, pale brownwith dark brown outer cells if apotheciumsessile.


Chemistry. C�, K�, KC�, Pd�. Nosubstances detected by TLC.

Remarks. Rhizocarpon caesium is a distinc-tive species that is usually easily identifiablein the field. Its blue-grey thallus, large,innate, flat apothecia and habitat of mildlybasic rocks (basalt, andesite, schists, etc.)readily separate it from R. infernulum.Microscopically it differs from R. infernulumin having a more vividly aeruginose epihy-menium (Cinereorufa-green), blue pig-mented paraphysoid caps and a higherhymenium. Previous records from Scotlandhave also been mistakenly named R. expal-lescens Th. Fr. (e.g. Gilbert & Fox 1986) butthat species occurs only on limestone andhas a K+ purple excipulum.

Rhizocarpon caesium is not a rare species inthe oceanic regions of Scotland where it ismost frequent on the basic, tertiary basalt ofthe Inner Hebrides (Fig. 3). The Welshcollections are also all from base-rich,igneous rocks. The records from further east(Mid- and East-Perthshire and Angus) arefrom mica-schist rocks in or near streams.Although no habitat details are available forthe East-Perthshire record, it was associatedwith Ionaspis lacustris (With.) Lutzoni [syn.Hymenelia lacustris (With.) M. Choisy],clearly placing it in this habitat. It is possiblethat flushing elevates the pH of the watersufficiently to provide a suitably basic habitatfor the lichen. Among the associated species

from its more typical habitat are Belonianidarosiensis, Placynthium tantaleum, Poly-blastia inumbrata, Porpidia superba and The-lidium papulare. The collection from Kerry(Ireland) was associated with Ephebe lanata,Ionaspis lacustris, Placopsis lambii, Polyblastiacruenta, Pterygiopsis coracodiza, Rhizocarponlavatum, Stereocaulon pileatum, Verrucariaaethiobola and V. hydrela.

The single collection from outside theBritish Isles (Queen Charlotte Islands, BritishColumbia, Canada) was from periodicallyinundated siliceous rocks around a high-altitude lake well known as a location forother rare species (Fig. 4A). This extremelydisjunct distribution pattern is known in anumber of other lichen species (see below).

Additional specimens examined. Great Britain: Wales:V.C. 49, Caernarfonshire: Cwm Idwal, Devil’sKitchen, 23/6358, on basic rocks, 1971, P. Harrold 958(E), ibid., S. of Twll Du, 23/6358, 550 m, verticalflushed basic crags, 1994, Fryday 5325; ibid., N. of TwllDu, 23/6358, 600 m, vertical flushed basic crags, 1994,Fryday 5328; Pass of Llanberis, Cwm Glas, 23/6155,750 m, basic rock above lake, 1994, Fryday [5708] &Chambers. Scotland: V.C. 88, Mid-Perthshire: BenLawers, Creag an Fhiathaech, 27/64,42, 850 m,mica-schist rock-face, 6 vii 1989, Fryday; BeinnHeasgarnich, Allt Lairig nan Lunn, 27/4338, 625 m,acid rocks beside stream, 1991, Fryday 2223. V.C. 89,East-Perthshire: Glen Shee, [37/17 or 37/16], 1930, W.Watson (BM). V.C. 90, Angus: Glen Clova, 37/305736,c. 300 m, in and beside small burn, 1991, R. C. Munros.n. V.C. 97, West Inverness-shire: Ardgour,Meall Breac, 17/9665, 250 m, 1992, Fryday 3150;Ardnamurchan, Beinn Hiant, 17/5363, 350 m, �basicbasalt crag, 1992, Fryday 3224. V.C. 98, Argyll Main:Glen Coe, Base of Aonach Dubh, 27/1556, 200 m,andesite crag, 1992, Fryday 3241. V.C. 104, NorthEbudes: Isle of Skye, The Storr, 18/4953, 500 m,exposed basalt crag, 1990, Fryday 1282; ibid., E crags ofSgurr Mor, 18/4470, 300 m, basalt crags, 1991, Fryday2920. V.C. 105, West Ross, Loch Maree, Letterewewoods, 1 km SE of Letterewe House, valley of Abhainnna Fàirness, 18/9575, 15–45 m, on boulder in stream,partly inundated at times, 1986, B. J. Coppins [11857]& R. Woods (E). V.C. 108, West Sutherland: BenHope, 29/4749, 550 m, on epidiorite outcrop, vii 1984,O. L. Gilbert s.n. (E); Inchnadamph, Ben More AssyntSSSI, 29/280230, 375 m, rock in stream ?basic flushing,1995, Fryday 6215.—Ireland: VC H1, South Kerry:Dingle peninsula, tributary of the OwennafeanaRiver near Slieveglass, Q495135, 190 m, fluvial-xericzone 22 vii 2001, V.J. Giavarini s.n. (hb Giavarini).V.C. H35 Donegal: Loughaderry River, N of Killybegs,G 724814, 70 m, on rock in fluvial-mesic zone withIonaspis lacustris, 20 vii 2001, V. J. Giavarini (hb.


Giavarini).—Canada: British Columbia: QueenCharlotte Islands, Moresby Island, Takakia Lake,52�56�N, 132�03�W, 590 m, along shore and in fens justback from shore on E side of lake [growing with Ionaspisspp.], 1967, I. M. Brodo [10878c] & M. J. Shchepanek(CANL).

968

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Rhizoc caesium

0 100km

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6

5

4

3

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2

3

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021

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09

WAHW

ChannelIslandsplotted onUTM grid

29 Jan 2001

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HXHW

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74

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F. 3. Distribution of Rhizocarpon caesium in the British Isles.

Rhizocarpon cinereovirens (Müll.Arg.) Vain.Acta Soc. Fauna Fl. Fenn. 53: 336 (1922).—Patillariacinereovirens Müll. Arg., Flora 51: 49. 1868; type: Prope

Bernam, Oct. 1867, J. Müller.—Catillaria concreta sensuKörber, Syst. Lich. German. 232 (1855), non sensuMassal. (G—lectotype selected here).

(Figs 5, 6A)

Thallus cracked-areolate to bullate, whiteto pale grey (occasionally pale brown),areoles 0·3–0·4 mm diam., flat (0·1 mmthick) to bullate [0·4–0·7(–0·8) mm thick];


B

Arctic Circle

Tropic of Cancer

A

Arctic Circle

Tropic of Cancer

F. 4. Known world distribution of A, Rhizocarpon caesium; B, R. infernulum f. sylvaticum.

prothallus rarely apparent, occasionallypresent at margins, fimbriate. Forming smallpatches <1 cm diam. or wide-spreading.Photobiont chlorococcoid, cells (6–)8–12(–14)�m diam.

Apothecia black, lecideine, flat and innateto slightly convex, (0·3–)0·4–0·6 mm diam.;proper exciple persistent but barely raised,0·04 mm wide, occasionally strongly convexwith excluded exciple. Hymenium hyaline,I+ blue, 70–90 �m tall; epihymenium olive-green to blue-black (Macrocarpa-green; K+greenish blue, N+ red-brown). Paraphysoidsc. 2·5 �m thick scarcely swelling at apex (to3·0 �m) with sharply delimited olivaceouscap; richly branched and anastomosing, not

separating in K. Asci c. 40–70�25–30 �m,Rhizocarpon-type. Ascospores hyaline,halonate, 1-septate, 8 per ascus, (11·0–)13·5–16·0(–18·0)�(5·5–)7·0–8·5 �m. Hy-pothecium dark to medium brown(Arnoldiana-brown). Excipulum poorlydeveloped, of radiating hyphae, pale brownwithin with a darker cortex.


Chemistry. C�, K+ orange or red, Pd+yellow or orange. Norstictic and/or sticticacid detected by TLC.

Typification. There are three specimensof Patellaria cinereo-virens in Müller’s


F. 5. Rhizocarpon cinereovirens, thallus and apothecia. A. typical form (Wetmore 7575); B, R. cinereovirens Britishform (Cwm Yswyth—hb. Chambers). Scale=1 mm.

herbarium in G labelled: Prope Bernam,Oct. 1867, Dr. J. Müller; Konitzwaldbei Bern. [no date, no collector]; Bern,

Müll. Arg. The protologue (Müller 1870)states ‘‘Ad saxa granitica prope Konitz inditioni bernensi’’ and as the first mentioned


collection is the only one that was definitelycollected by Müller before the date of pub-lication it is here selected as the lectotype.

Remarks. Previously (Fryday 1996), Ibelieved R. cinereovirens to be a norsticticacid containing race of R. infernulum (as R.hochstetteri) with British specimens referredto R. cinereovirens representing a distincttaxon. However, examination of additionalmaterial from Europe and North Americahas shown that there are clear, if subtle,differences between R. cinereovirens and R.infernulum and that the British collectionsfall within the range of variation of R.cinereovirens. Rhizocarpon cinereovirens differsfrom R. infernulum in having a less well-developed exciple with a hyaline interior,and more richly branched and anastomosingparaphysoids with less sharply defined caps(Fig. 6A) that are olivaceous rather thanbrown. The thallus also generally containsnorstictic acid (occasionally only stictic acid)rather than no substances or stictic acid inR. infernulum.

The lectotype of R. cinereovirens, andother collections from Europe and NorthAmerica, have an areolate thallus with dis-tinctly marginate, �innate apothecia (Fig.5A), whereas British collections often have amuch reduced thallus of convex areolesand �immarginate apothecia (Fig. 5B).However, the anatomy of the apothecia ofthese specimens appears identical to thelectotype, and other specimens referred toR. cinereovirens, and it is probable that thethalline characteristics are an environmentalmodification resulting from the ‘stressed’conditions in which the British specimensoccur.

In the British Isles R. cinereovirens is aspecies of exposed siliceous rocks. It is par-ticularly frequent on the spoil of disusedmetal mines in Mid Wales (7 sites—S. P.Chambers, pers. comm.) and has also beenrecorded from this habitat in North Wales(Caernarvon) and Scotland (Argyll). Itis otherwise known only from the summits ofthe Ben Nevis range (Ben Nevis, AonachMór) and maritime heaths in NE Scotland(Coul Links, Culbin Forest). On the

Welsh mine sites associated species includeAcarospora sinopica, Buellia aethalea, B.ocellata, Lecanora polytropa, Rhizocarponhochstetteri, R. reductum and Stereocaulonleucophaeopsis, whereas the Scottish high-altitude collections are associated withCecidonia xenophana, Porpidia sp., Rhizo-carpon infernulum and Stereocaulon tornense.

Rhizocarpon discoense Lynge, usuallyincluded in the synonymy of R. cinereovirens(Thomson 1967; Timdal & Holten-Hartwig1988), has a similar apothecial anatomy ofbranched paraphyses with greenish pig-mented tips and small, hyaline 1-septateascospores, but differs in having a well-developed exciple with a purple pigmen-tation (K+ purple), a thallus consisting ofgrey bullate areoles, and ascospores towardsthe upper end of the range (16·0–17·0�9·0–10·0 �m). These differences aresufficient to warrant recognizing R. discoenseas a distinct species. I have seen only theholotype collection from Disko Island,Greenland [Disko, Sinigfik, on a stone cairn,built of hard, dense rock, 1932, Lynge (C)].

An apparently undescribed species ofRhizocarpon from the Queen CharlotteIslands, British Columbia, Canada, has asimilar exciple structure to that of R. cinereo-virens. It is confined to maritime rocks in thesalt spray zone, has apothecia in which themargin is consistently paler than the disc,and a thallus consistently containing onlystictic acid (I. M. Brodo, pers. comm.).

Selected specimens examined. Great Britain: Wales:V.C. 46, Cardiganshire (Ceredigion): Strata FloridaMine, Strata Florida, 22/743662, 190 m, well-lit minespoil, 17 iv 1993, S. P. Chambers & A. M. Fryday (E,NMW); Bwlch Glas Mine, Cyneiniog Valley, 22/710877, 250 m, S-facing mine spoil, 24 v 1993, S. P.Chambers (hb. Chambers); Cwmystwyth Mine, CwmYstwyth, 22/800747, 350 m, S-facing spoil tip, 15 ix1993, S. P. Chambers (hb. Chambers); Ystrad EinionMine, Cwm Einion, 22/707939, 200 m, semi-shelteredspoil tip in forestry, 19 xi 1993, S. P. Chambers (hb.Chambers). Scotland: V.C. 95, Moray: Culbin Sands,28/96, 0 m, on pebble on shingle ridge in area ofstunted Pinus, 1986, B. J. Coppins 11573 (E). V.C. 97,West Inverness-shire: Aonach Mór, Fort William, 27/1873, 1150 m, pebble on the ground near summit,1990, Fryday [1204], O. L. Gilbert & B. J. Coppins;ibid., Seang Aonach Mór, 27/11972, 1090–1200 m onrocks at top of gully, edge of late snow patch, 1990,B. J. Coppins [13813] O. L Gilbert & A. M. Fryday; Ben


F. 6. Rhizocarpon hochstetteri s. lat., sections of apothecia and paraphysoids. A, R. cinereovirens (Wetmore 7575);B, R. infernulum f. infernulum (Fryday 5053);. C, R. infernulum f. sylvaticum (Fryday 3007—holotype).

Scale=100 �m (apothecia), 25 �m (paraphysoids).

Nevis, Fort William, 27/1671, 1340 m, siliceous pebbleon summit plateau, 1990, Fryday [1368], V. J.Giavarini & O. L. Gilbert. V.C. 98, Argyll Main:Coire Cheilein, Tyndrum, 27/3133, 350 m, disusedmetal-mine spoil, 1991, Fryday 2198. V.C. 107, East

Sutherland: Coul Links, c. 5 km N of Dornoch, 28/810950, 0 m, on pebble in dune heath, 1983, B. J.Coppins [9869], A. Fletcher, P. W. Lambley & R. K.Brinklow (E).—Finland: Karelia ladogensis: Sortavala,Myhkii. In regione supra-aquatili rupis umbrosae in


ripa septentriones et ortum solis spectanti, 14 vii 1939,A. Pankakoski [Räsänen, Lich. Fenn. Exs. No. 649](MICH).—Sweden: Närke, Svennevad, Norrängen,21 June 1949, G. Kjellmert (MICH); rocks Hellblom(MICH—ex herb B. Fink 1241).—Switzerland: seecitation of lectotype.—Canada: Ontario: HastingsCounty, Card Lake, 6 km W of Bancroft, 45�03�N,77�56�W, on non-calcareous boulder in white birch,maple, fir forest, October 1986, P. Y. Wong [4319] &D. Wong (CANL).—USA: Missouri: Shannon County,Carr’s Creek State Forest, 2 miles E of Current River,1997, D. Ladd 20649 (hb. Ladd). New York: LongIsland, Suffolk County, Noyack, Oak-Hickory woodson Noyack road opposite Jessups Neck, granite boulderin clearing, 1960, I. M. Brodo 2173 (MSC); ibid.,Amagansett, Oak-Hickory wood on ‘Bunker Hill’ onBunker Hill Rd, 1961, I. M. Brodo 3265 (MSC); ibid.,Northwest, Oak-Hickory woods, old Northwest Roadand Alewife Road, small boulder in sun, 1962, I. M.Brodo 3899 (stictic acid only) (MSC). South Dakota:Custer County, above Game Lodge in Custer StatePark, (11 miles E of Custer), Sec. 27, T. 3S, R. 6E,1300 m, gently sloping northerly exposure, 1960, C. M.Wetmore 7575 (MSC); Lawrence County, along BearButte Creek, 1·1 miles S of U.S. 386 (6 miles W ofLead), Sec. 17, T. 4N, R. 4E, 1550 m, steep N facingslope above creek, 1960, C. M. Wetmore 8668 (MSC);Pennington County, one mile W of Pactola WorkCentre on S.D. 40 (13 miles W of Rapid City), Sec. 35,T. 2N, R. 5E, 1400 m, gently sloping northerly expo-sure, 1960, C. M. Wetmore 8730 (MSC); ibid., alongPine Creek at head of Horse Thief Lake (18 miles SWof Rapid City), Sec. 11, T. 2S, R. 5E, 1500 m, in shadyvalley with stream, 1961, C. M. Wetmore 10 994(MSC). Vermont: Lamoille County, Mt Mansfield StateForest, Runny Nose Spring, alpine area just below thenose, 72�48�54�W 44�31�41�N, 1190 m, krumholz andsiliceous ledges in the open, 2000, E. Lay 00-0060 (hb.Lay).

Rhizocarpon infernulum (Nyl.) Lyngef. infernulumRhodora 36: 158 (1934).—Lecidea infernula Nyl., Flora68: 440 (1885); type: Fretum Behringii, Ins.Behringii, [Ostrov Bering] 1878–89 (Exped. Vega), S.Almquist (H–NYL 10044—lectotype selected here;10043, 10014 and 10074—topolectotypes).

Lecidea decinerascens Nyl., Flora 68: 445 (1885).—Rhizocarpon decinerascens (Nyl.) Zahlbr., Cat. Lich.Univ. 4: 332 (1926); type: Fretum Behringii, S.Lawrence Bay [Bering Strait, Zaliv Lavrentiya],1878–89 (Exped. Vega), S. Almquist (H–NYL 10077—lectotype selected here; 10075—topolectotype).

(Figs 6B 7, 8)

Thallus rimose to cracked areolate, brownor grey to very pale grey; areoles 0·3–0·4 mm

diam., flat. Photobiont chlorococcoid, cells(10–)12–15(–18) �m diam.

Apothecia black, lecideine, flat and innateto slightly convex, 0·3–0·4(–0·5) mm diam.;proper exciple (if apparent) thick (0·02–0·03 mm) but barely raised. Hymenium hya-line, I+ blue, 70–90 �m tall; epihymeniumusually with aeruginose to blue-black pig-ment (Macrocarpa-green; K�, N+ red).Paraphysoids c. 2·5 �m thick scarcely swell-ing at apex (to 3·0 �m) with sharplydelimited brown (Atra-brown) cap,branched and anastomosing. Asci c. 70�30 �m, Rhizocarpon-type. Ascospores hyaline,halonate, 1-septate, 8 per ascus, 15–18�7–8·5 �m. Hypothecium brown (Arnoldiana-brown). Excipulum well-developed, ofradiating hyphae, pale brown with darkbrown, carbonaceous outer cells.


Chemistry. C�, K� or K+ yellow, Pd�or Pd+ orange. No substances or stictic aciddetected by TLC.

Typification. Nylander (1885: 440, 445)described the two new species Lecidea infer-nula and Lecidea decinerascens from collec-tions made by S. Almquist during the VegaExpedition of 1878–89 to the Bering Sea. Itis difficult to find any significant differencesbetween these two taxa, either in Nylander’sdescriptions or in the specimens upon whichthey are based. Vainio (1922) correctly con-sidered them conspecific and referred bothspecies to R. hochstetteri f. infernulum (‘infer-nula’), whereas Thomson (1967) includedboth taxa within R. hochstetteri. According toThomson (1967), H–NYL 10077 is ‘thetype’ of L. decinerascens, but as this does notappear to have been published I here desig-nate this specimen as the lectotype. H–NYL10075, from the same locality (FretumBehringii. S. Lawrence Bay) is a topolecto-type. Lecidea infernulum does not appear tohave been typified and, as the specimens ofL. infernulum are better developed thanthose of L. decinerascens, I have chosen to usethat name for the species and designateH–NYL 10044 as the lectotype. The threeother collections, H–NYL 10043, 10014


F. 7. Rhizocarpon infernulum, thallus and apothecia. A, R. infernulum f. infernulum (Fryday 5053); B, R. infernulumf. sylvaticum (Fryday 3007—holotype). Scale=1 mm.

and 10074, from the same locality (FretumBehringii, ins. Behringii), being topolecto-types.

Remarks. The material in H–NYL agreeswell with specimens from the British Isles.All have a reduced thallus of dispersed


F. 8. Rhizocarpon infernulum f. infernulum (Fryday 5053), ascospores. Scale=25 �m.

areoles and �sessile apothecia with athick, barely raised exciple. Internally,the lectotype has a brownish epihymeniumwith swollen paraphysoid tips that are �conglutinate in K.

Rhizocarpon infernulum is a species ofsiliceous rocks where it forms small patches,usually <2 cm diam (Fig. 7A). In the BritishIsles it is most frequent on the spoil ofdisused metal mines, but also occurs onsiliceous rocks at all altitudes, although itis more frequent in upland to montaneregions. Associated species, which includePorpidia tuberculosa and Rhizocarpon reduc-tum, suggest that it may be a colonizingspecies or one adapted to stressed habitatsgenerally. I have not seen any specimens ofthis taxon from North America, but I have,so far, looked at very few specimensfrom the Arctic or Boreal regions. Thomson(1967, 1997) includes this taxon in R. hoch-stetteri but, as it is known from Greenland

(see below) and Degelius (1937) includesa record from the Aleutian Islands (asR. hochstetteri f. infernulum), I have nodoubt that it occurs throughout the NorthAmerican Arctic.

Rhizocarpon infernulum is a variable taxonwith respect to thallus colour (brown toalmost white) and form (dispersed-areolateto smooth-continuous), chemistry (no sub-stances or stictic acid), and ecology (exposedmontane heaths to rock outcrops in wood-lands). However, it is characterized byhaving paraphyses with brown (Atra-brown), sharply delimited, swollen caps,although these are usually masked by theblue-green pigment (Macrocarpa-green)present in the upper hymenium. The collec-tions from shaded woodlands, with a thinbrown thallus and prominent apothecia(Fig. 7B), are considered sufficiently distinctto merit description below as a separateforma.


Selected specimens examined. Great Britain: Wales:V.C. 46, Cardiganshire (Ceredigion): Pont-y-rwyd,Dyffrin Castell mine, 22/773812, 300 m, block spoil,1994, Fryday [5017] & S. P. Chambers; Elerch, Llan-y-cwm-bach mine, 22/708854, 230 m, block spoil,1994, Fryday [5037 & 5045(E)] & S. P. Chambers.V.C. 47, Montgomeryshire: Gafron Mine, N of RiverSevern, 22/885856, 300 m, steep, S-facing spoil-tip,2 viii 1993, S. P. Chambers s.n.; Dylife, Dylife mine,22/863939, 360 m, spoil, 21 January 1994, S. P.Chambers [s.n.] & Fryday; ibid., 22/862934, 375 m,block spoil, 1994, Fryday [5073 &5083] & S. P.Chambers. V.C. 49, Caernarvon: Gwydyr Forest,Allt-lan mine, 23/780591, 250 m, well-lit spoil, 11 xi1994, S. P. Chambers s.n.; ibid., New Pendore (WelshFoxdale) Mine, 23/767600, 240 m, metal-rich spoil, 23xi 1994, S. P. Chambers s.n. Scotland: V.C. 88, Mid-Perthshire: Glen Dochart, Ledcharrie, 27/5028, 150 m,acid rock, October 1989, Fryday s.n. V.C 90, Angus:Drumore, E of Drumore Loch and Nether Crag, 37/172612, 375 m, metal-rich rocks in roadside quarry,pre- 31 viii 1995, R. C. Munro s.n. (E, hb. Fryday).V.C. 96/V.C.106, East Inverness-shire/East Ross: MamSodhail, 28/120253, 1180 m, flat stone in summitheath, 1994, Fryday 5500. V.C. 97, West Inverness-shire: Aonach Mór, Fort William, 27/ 1873, 1150 m,pebble on the ground near summit, 1990, Fryday[1204], O.L. Gilbert & B. J. Coppins; Ben Nevis, FortWilliam, 27/1671, 1340 m, siliceous pebble on summitplateau, 1990, Fryday [1368], V. J. Giavarini & O. L.Gilbert. V.C. 98, Argyll Main: Glen Coe, Bidean namBian, 27/141542, 1140 m, pebble in summit heath,1995, Fryday 6184. V.C. 104, North Ebudes: Isle ofSkye, E side of Loch Slaplin, Camas Malag, 18/5818-9,alt. 0–60 m, on low basaltic dyke, 25 v 1987,B. J. Coppins 11724 (E).—Russia: see citation oflectotypes.—Greenland: Godhaven, Kontaktryggen,69�N 53�W, alt. 90 m, 1953, P. Gelting 20515 (C).

Rhizocarpon infernulum formasylvaticum Fryday forma nov.Rhizocarpon infernulo f. infernulo similis sed thallo tenui,0·05–0·08 mm, continuo vel rimoso, dilute brunneo,sine substantiis lichenis, prothallo nigro visibili; asco-matibus sessilibus, excipulo proprio tenui et persistenti,epihymenio vulgo sine pigmento aeruginoso.

Typus: Cambria, V.C. 48, Merioneth, Ganllywd,23/7223, 100 m, siliceous rock wall at edge of dampwoodland, A. M. Fryday 3007 (E—holotypus).

Rhizocarpon massalongoi sensu Malme . . . massalongoiKörb. (see p. 456), Lich. suec. exs. fasc. 5, no. 124(1909), non Catillaria massalongoi Körber.

(Figs 4B, 6C, 7B)

Thallus thin, 0·05–0·08 mm thick, palebrown, areoles flat, 0·2–0·5 mm diam.,smooth, becoming areolate on a well-developed black prothallus towards the mar-gins and rimose in thicker areas towards the

centre. Photobiont chlorococcoid, cells (6–)8–12(–14) �m diam.

Apothecia black, lecideine, sessile with thinpersistent proper margin, (0·2–)0·3–0·5(–0·7)mm diam. Hymenium hyaline, I+ blue, 75–90 �m tall; epihymenium rarely with bluepigment (Macrocarpa-green; K�, N+red), not granular. Paraphysoids c. 1·5 �mthick swelling at apex to 3·0 �m withsharply delimited brown (Atra-brown) cap,branched and anastomosing, readilyseparating in K. Asci 60–70�25–28 �m,Rhizocarpon-type. Ascospores hyaline, halo-nate, 1-septate, 8 per ascus, 17·5–19(–20)�8·5–11·0 �m. Hypothecium medium brown(Arnoldiana-brown). Excipulum of radiatinghyphae, pale brown with dark brown,carbonaceous outer cells.


Chemistry. C�, K�, KC�, Pd�. Nosubstances detected by TLC.

Nomenclature. Malme made the new com-bination Rhizocarpon massalongoi in Lich.suec. exs. fasc. 5, no. 124 (1909). The singlespecimen of this number that I have seen(MIN—see below) is referable to R. infernu-lum f. sylvaticum. As Vainio (1922) includesR. massalongoi as a synonym of R. hochstetterif. incrassatum (‘incrassata’) (Vain.) Vain. andcites Malme’s exsiccati number, I thoughtthat this may be an earlier name for thistaxon. However, the syntypes of this taxon inTUR-V are referable to R. hochstetteri s. str.(see above)

Remarks. Previously, I referred to thistaxon as ‘R. oceanicum’ (Fryday 1996), butsubsequent investigation has shown thatit intergrades with typical forms of R. infer-nulum and is not worthy of specific rank.Rhizocarpon infernulum f. sylvaticum is fre-quent on damp siliceous rocks, boulders andwalls in the oceanic woodlands of the west-ern British Isles, but also occurs on damprocks at high altitude in western Scotland(e.g. Ben Cruachan), and on upland/montane rocks in the south-western BritishIsles, for example Bodmin Moor (SWEngland), Brandon Mountain (SW Ireland).


It appears to be most frequent in Wales,becoming less common further north inScotland, although its distribution is difficultto assess accurately because of previous con-fusion with R. hochstetteri. Records of R.hochstetteri from The Azores (O. W. Purvispers. comm.) are also possibly referablehere.

Rhizocarpon infernulum f. sylvaticum is alsofrequent in eastern North America; the illus-tration of R. hochstetteri in Brodo et al.(2001) is this taxon, and much of thedescription they provide (thin, smooth thal-lus; apothecia with thin, persistent margin;usually in damp or shaded sites) refers to it.It has been collected from Quebec to NorthCarolina and as far west as Minnesota, buthas yet to be recorded from western NorthAmerica (Fig. 4B). This amphi-atlantic dis-tribution is rare and not easy to explain butis possibly a consequence of the taxon’sapparent affinity with deciduous woodland(see below).

Rhizocarpon infernulum f. sylvaticum isusually easily separated from f. infernulum inthe field by its habitat, thin, continuous,olivaceous-brown thallus, and sessile apoth-ecia with a narrow prominent margin (Fig.7B). However, intermediates do occur, andthese can be impossible to place. Internally,the apothecia of f. sylvaticum are charac-terized by their very lax paraphysoids,especially in K. This character, combinedwith the sharply delimited pigmented caps ofthe paraphysoids (Fig. 6C) and the 1-septateascospores, gives apothecia sections theappearance of a Catillaria sp. However, R.infernulum f. sylvaticum can be separatedfrom members of that genus by its anasto-mosing paraphysoids and different ascusstructure.

The epihymenium of f. sylvaticum isinvariably hyaline, allowing the brown (Atra-brown) pigmented tips of the paraphysoidsto be clearly visible. As it is the blue-greenpigment (Macrocarpa-green) that is respon-sible for the N+ red reaction of the epihy-menium in f. infernulum (and other speciesof the R. hochstetteri group), this reaction isalso absent. Occasionally a small amount ofMacrocarpa-green is present, in which case

there is a slight N+ red reaction. The pres-ence of Macrocarpa-green appears to berelated to the degree of sun-exposure of thespecimen as it is absent in f. sylvaticum,which occurs in damp shaded woodlands,but most abundant in those specimens of f.infernulum that occur on exposed montanerocks (e.g. Fryday 1204, 1368, 5500, 6184).The degree of separation of the paraphysoidsalso appears to be inversely related to theamount of Macrocarpa-green produced.Consequently, as f. sylvaticum occurs inshaded deciduous woodlands, it has ahyaline epihymenium and paraphysoidsthat separate readily, whereas f. infernu-lum, which occurs in more exposed situ-ations, has a blue-black epihymenium andcontiguous paraphysoids.

The holotype of R. infernulum f. sylvaticumwas growing with the bryophyte Racomitriumheterostichum. Species associated with othercollections include Porpidia tuberculosa andRhizocarpon reductum.

Selected additional specimens examined. GreatBritain: England: V.C. 2, E. Cornwall: Bodmin Moor,Rough Tor, 20/1480, E.M. Holmes (BM). V.C. 3, S.Devon: Carnwood, 20/6059, v 1932, W. Watson (BM).V.C. 70, Cumberland: Borrowdale, High Style Wood,35/2413, acid rock in woodland, iv 1988, Fryday.Wales: V.C. 42, Brecnockshire: Abergwesyn, NantIrfon, 22/840548, 330 m, shaded, flushed siliceousrock-face on E-facing slope, 1 xi 1997, Fryday& S. P. Chambers. V.C. 46, Cardigan (Ceredigion):Devil’s Bridge, Bodcall Mine, 22/758768, 270 m, sili-ceous crags, 1994, Fryday [5029] & S. P. Chambers.V.C. 48, Merioneth: Barmouth, Capel Arthog, ?23/6414, vi 1875, W. A. Leighton (BM). Scotland: V.C. 73,Kirkcudbrightshire: St John’s Town of Dalry, OldGarroch, 25/5982, on mossy rock, 24 iv 1976, P. W.James s.n.(BM). V.C. 88, Mid-Perthshire: Killin, Alltna Ceardach, 27/5734, 175 m, acidic boulder in stream,1991, Fryday 2027. V.C. 98, Argyll Main: North PortSonachan on Loch Awe, 105 m on schistose rock at topof hillock, 1940, I. M. Lamb 1021 (CANL); Loch Awe,Lower Fernoch, 27/0119, 50 m, acid rock in woodland,1991, Fryday (2242) & R. Leishman; Ben Cruachan27/0730, 1100 m, shaded underhang on N side of ridge,1994, Fryday (5584); Invarary, Glen Shira, Kilblaanravine, 27/1313, 50 m, on schistose boulder bywoodland path, 1996, B. J. Coppins [16842] & A. M.Coppins (E).—Ireland: V.C. H1, South Kerry: DinglePeninsula, Connor’s Pass, Lough Doon, 01/5006,500 m, siliceous boulders near loch, 1994, Fryday[5185] & O. L. Gilbert. V.C. H16, West Galway:Connemara, Nr Kylemore, River ?Urar, 1878,Larbalestier (BM).—Sweden: Uppland: Värmdön,


Hasseludden, in rupibus saepe irrigatis, viii 1908,G. Malme (MIN). Bohuslän: Hjärtum, Hasteröd,v 1936, J. B. Headvall (CANL) (aeruginoseepihymenium).—Canada: New Brunswick: FundyNational Park, Kinnie brook, at dam site near Highway114, 45�36�N, 65�00�W, on rock, unshaded part ofoutcrop above dam, 1980, S. P. Gowan 3912 (CANL).Ontario: Frontenac County, Bon Echo National Park,100 km NNW of Kingston, 44�54�N 77�12�W, HighPines Trail, mixed woods with Acer, Pinus Thuja, Fagus,on rock in shaded woods, 1989, I. M. Brodo (27568) &F. Brodo (CANL). Quebec: Papineau County, 3·5 milesN. of Mayo, along Riviere Blanche, 45�42�N 75�21�W,240–275 m, W-facing slope and summit area of steephill, Red Oak-Birch-Maple stand and granitic outcrops,1980, I. M. Brodo [23562 & 23603], P. Y. Wong, S.Gowan & G. Savage (CANL); Gatineau County, LacLapeche, 45�37�N 76�12�W, 425 m, on N- andW-facing slopes on E edge of lake, with mixed hard-wood forest, 1969, I. M. Brodo [16381] & S. A. O’Neill(CANL); 7 km E. of Low on Low-Poltimore road,45�48�N 75�52�W, on shaded boulder in Acersaccharum-Fagus forest on hillside and alongbrook, 1989, I. M. Brodo [27640], U. Arup & S.Ekman (CANL).—USA: Minnesota: St Louis County,Voyagers National Park, Sec. 31, T69N, R19W,Sullivan Bay off eastern end of Kabetogama Lake. Onsteep hillside on S side of bay with black spruce and redpine and a few white pine and balsam fir, 1978, C. M.Wetmore 32802 (CANL). New York: Adirondack Mtns,vicinity of Lake Placid, Mt Marcey, Avalanche Lake,lake surrounded on two sides by high cliff faces ofU-shaped valley, on low boulders of cliff talus near lakeshore, along path at edge of talus overgrown by lowtrees and shrubs, moist and mossy, 1998, J. Buschbom2954 (MSC). North Carolina: Macon County-JacksonCounty, Whiteside Mountain, 5·5 miles E of Highland,1360–1498 m, at summit, oak forest and rock outcrops,on wet wall on trail, 1981, I. M. Brodo [23836] & S. P.Gowan (CANL).

Discussion

British and European ascosporedimensions of R. hochstetteri

Authors from continental Europe fre-quently quote smaller ascospore dimensionsfor Rhizocarpon hochstetteri than Britishauthors, for example, 10–25�6–11 �m(Feuerer 1978; Wirth 1980), 17–28�9–13 �m (Timdal & Holten-Hartwig 1988),10–29�6–11 �m (Foucard 1990) against25–36�12–16 �m (Duncan 1970), and 25–36�12–17 �m (Dobson 2000). Purvis et al.(1992) recognized this discrepancy, compar-ing their dimensions of 25–32�12–15 �mwith a figure of 10–25�6–11 �m given bycontinental authors.

Initially, it was believed that this dis-crepancy was a consequence of the threespecies (R. hochstetteri, R. infernulum andR. caesium) involved in British collectionsreferred to R. hochstetteri. However, the asco-spore dimensions of these species, corre-spond only to those given for R. hochstetteteriby continental authors, with the ascosporedimensions given by British authors beinglarger than those of any of the species in-volved. Examination of a large number ofspecimens referred to R. hochstetteri in E andBM revealed that many were referable to R.polycarpum, including specimens collectedand determined by Ursula Duncan. As thelength of the ascospores in this species arein the range 22–36 �m, this explains theerroneous ascospore dimensions given forR. hochstetteri by Duncan (1970) and per-petuated by Purvis et al. (1992) and Dobson(2000). These misdeterminations are puzz-ling as the differences between the twospecies (R. polycarpum has an I+ bluemedulla and a K+ purple epihymenium)were correctly indicated by Duncan (1970).This confusion was not limited to Britishauthors, however, as the specimens distrib-uted as R. hochstetteri by Poelt (LichenesAlpinum No. 65; M. Steiner, 1958) are alsoR. polycarpum.

Phytogeography of Rhizocarponspecies

The apparent world distribution patternsexhibited by crustose lichens must be treatedwith caution because they are poorly col-lected, especially in critical tropical andSouthern Hemisphere areas. However, forthe taxa under consideration here, sufficientmaterial has been examined from temperateEurope and North America to enable atentative assessment to be made of theirmajor distribution patterns. Examinationof more material from Scandinavia andthe North American Arctic will hopefullyconfirm the trends detected so far.

Of special interest are the different distri-bution patterns of Rhizocarpon caesium andR. infernulum f. sylvaticum (Fig. 4). Both taxaare frequent in the western British Isles, but


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whereas R. caesium has otherwise been re-corded only from the Pacific North-West ofNorth America, R. infernulum f. sylvaticumis frequent in eastern North America butabsent further west. Both these distributionpatterns are rare in vascular plants but morefrequent in cryptogams, especially lichens(e.g. Ahti 1977; Dahl 1998; Ihlen & Fryday2002; Printzen & Ekman 2002; Tønsberg1990, 1993).

I have not examined a large number ofRhizocarpon collections from the Arctic, butR. hochstetteri s. str. and R. infernulum f.infernulum appear to have a circumboreal/Arctic distribution. The amphiatlantic distri-bution of R. infernulum f. sylvaticum wouldappear to be an extension of the range ofR. infernulum into more temperate areas,because it approximately corresponds to theextent of deciduous forests. This wouldalso explain its absence from the PacificNorth-West where coniferous forests pre-dominate. The distribution of R. infernulumf. sylvaticum also corresponds to the south-ern extent of the last extensive glaciation(Pleistocene) of the Northern Hemisphere,which ended c. 13–12 000 BP. During thisglaciation, the environment of the areawould have been similar to that furthernorth where R. infernulum f. infernulumoccurs today, and it is probable that, as theice retreated northwards, R. infernulumf. infernulum retreated with it, and thef. sylvaticum developed as a response tothe encroaching deciduous forests.

The north-western Europe/north-westernNorth America disjunct distribution patternof R. caesium is one shared by numerousother lichens, for which the term ‘Trøndelaglichens’ has recently be coined (Holien &Tønsberg 1996; Printzen & Ekman 2002).Both areas have a highly oceanic climate(A. B. G. Averis unpublished MSc thesis),characterized by high rainfall and low sea-sonal temperature variation (mild winters,cool summers), which leads to the develop-ment of a characteristic, and extremelydiverse lichen flora that is not found in morecontinental areas (Fryday 2002). It is un-clear whether this present distributionpattern is the consequence of long-range

dispersal, or represents relict populations ofa once more widespread species.

Pigmentation of the epihymenium

According to the system of Meyer &Printzen (2000), the pigment in thehymenium of all the species discussed here isCinereorufa-green. This is certainly the casefor R. caesium (see above), but the oli-vaceous green to blue-black pigment presentin the other species may be different. Thispigment is not only much duller blue inwater, but the colours in high and low pHare also less intense. In particular, the colourof the pigment after pre-treatment with 50%HNO3 is grey-green in high pH (greenish-blue for Cinereorufa-green), and red-dish brown in low pH (violaceous forCinereorufa-green). A similar situationoccurs in the genus Porpidia Körb., in whichthe distinctive aeruginose epihymenium ofP. hydrophila (Fr.) Herte l & A. J. Schwabis Cinereorufa-green, but the dullerolivaceous-green epihymenium of most ofthe other species of the genus [e.g. Porpidiamacrocarpa (DC.) Hertel & A. J. Schwab]is due to the same pigment present in theR. hochstetteri group. For these reasons Ipropose the name Macrocarpa-green isproposed for this pigment.*

Usefulness of characters indistinguishing species

ThallusThe thallus in many species of Rhizocar-

pon ranges from a few isolated areoles on anextensive black prothallus to well developedand, at times, almost subsquamulose (e.g. R.reductum, Fryday 2000b). However, manyspecies have either a thallus composed ofrounded bullate areoles with a smooth sur-face (e.g. R. geminatum, R. grande) or a morecontinuous, cracked areolate thallus (e.g.R. lavatum, R. caesium).
*Macrocarpa-greenBased on: Porpidia macrocarpa (DC.) Hertel & A. J.Schwab in Hertel, Beiheft zur Nova Hedwigia 79: 437(1984). Basionym Patellaria macrocarpa DC. in Lam &DC. Fl. Franç., Ed. 3 2: 347 (1805)Reference Collection: Hertel, Lecideaceae Exs. No. 276


Thalline chemistry is equally variable,especially with regard to stictic/norsticticacid (which is the only substance producedin the species under consideration here). It isnot unusual to find species that usuallyproduce stictic acid also occasionally pro-ducing norstictic acid or no substances thatare detectable by spot-tests or TLC (e.g.R. reductum Th. Fr., Feuerer 1991; Fryday2000b).

ParaphysoidsThe degree of branching/anastomosing of

the paraphysoids is taxonomically signifi-cant, although it is both variable and difficultto quantify. However, it can be a usefulcomparative character (e.g. the paraphysoidsof R. cinereovirens are more branched/anastomosing than those of R. infernulum).The degree of swelling of the paraphy-soid tips and their pigmentation are also

ApotheciaUsually in the range 0·3–0·7 mm, slightly

convex with a thin barely raised exciple.However, in some species they are unusuallylarge (e.g. R. caesium, R. lavatum) or un-usually small (e.g. R. anaperum). Others mayhave a thin persistent exciple (e.g. R. infer-nulum f. sylvaticum) or one that can beexcluded even in young apothecia (e.g. R.cinereovirens). It is probable that thischaracter is subject to considerable environ-mental modification. The location of theapothecia on the thallus is probably sig-nificant; that is whether they arise from thecentre or sides of the areoles, or fromthe prothallus.

AscosporesMost characters are useful at the species

level (i.e. size, shape, septation, pigmen-tation) provided only mature ascospores areconsidered. Immature ascospores of specieswith muriform ascospores may be onlytransversely septate, whereas those of specieswith dark coloured ascospores may be hya-line. Conversely, ascospores of hyaline-spored species often become pigmentedwhen over mature, and 1-septate ascosporescan develop additional septa. Pigmentationis, otherwise, usually a reliable character,although in some species (e.g. R. hochstetteri,R. subpostumum) it is possible to find maturehyaline and coloured ascospores in the sameapothecium. Shape (length-breadth ratio) isa useful character for ascospores above c.20 � long but appears to be more variable forsmaller ascospores. Degree of constriction atthe septum (at least in species consideredhere) is variable, even in ascospores from thesame ascus (Fig. 8).

HymeniumDue to the ontogeny of the hamathecia of

Rhizocarpon (by vertical stretching, produc-ing paraphysoids), the height of the hy-menium is likely to be more variable than ingenera with true paraphyses, which growupwards from the subhymenium. However,provided mature apothecia are examinedthis parameter is fairly constant and themaximum height attained can be a goodcharacter for separating species.

The pigmentation of the epihymeniumvaries within individual species, although itis important to distinguish between the pig-mentation of the epihymenium and that ofthe paraphysoid tips. It is often the case thata blue-green (Macrocarpa-green) or purple(Atra-red) pigment in the epihymeniumgives the impression that the paraphysoidtips are similarly pigmented when they are,in fact, brown (Atra-brown) (e.g. R. hochstet-teri, R. infernulum). In the R. hochstetterigroup the epihymenium varies from hyalineto blue-black depending upon the quantityof Macrocarpa-green produced. Productionof this epihymenial pigment appears to berelated to the degree of exposure to whichthe specimen is subjected, and is responsiblefor the degree of separation of the para-physoids (see above under R. infernulum f.sylvaticum).

The pigment present in the epihymeniumis also present in the exciple. In taxa in whichthe epihymenium usually contains Atra-redand has a corresponding K+ purple reaction(e.g. R. polycarpon, R. distinctum, R. chio-neum), this pigment (and the resulting K+reaction) is sometimes lacking in the epi-hymenium but is invariably present in theexciple, which is consistently K+ purple.


taxonomically significant, although the latteris often masked by other pigments present inthe epihymenium.

Key to the non-yellow species of Rhizocarpon, with hyaline, 1-septate ascospores

A revised key to the non-yellow species of Rhizocarpon with hyaline, 1-septate ascospores isincluded to replace those provided by Thomson (1967, 1997), Feuerer (1978), Timdal &Holtan-Hartwig (1988), Purvis et al. (1992) and Fryday (1996). Further work remains to bedone on the R. richardii/R. polycarpon and R. caeruleoalbum/R. chioneum/R. expallescensgroups and the works mentioned above should be consulted for further details of thesespecies.

1. Parasitic on Tremolecia atrata. Thallus greyish-yellow (unknown pigment);ascospores 12·5–15·0�6·5–8·0 �m (not recorded from the British Isles) . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. santessoniiSpecies autonomous; thallus white, grey or brown . . . . . . . . . . . . . . . . 2

2(1). Medulla I+ blue; ascospores occasionally becoming 3-septate or submuriform. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Medulla I�; ascospores usually remaining 1-septate . . . . . . . . . . . . . . 4

3(2). Thallus usually C+ red (gyrophoric acid); epihymenium K�; maritime species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. richardii

Thallus usually C�; epithecium K+ purple (Atra-red); upland/montane species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. polycarpum

4(2). On basic rock (HCl+effervescence) . . . . . . . . . . . . . . . . . . . . . . . . 5On siliceous rock (HCl�) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5(4). On slightly calcareous rocks (epidiorite, basalt, andesite) in oceanic areas; rarely onsemi-inundated siliceous rocks further east (Scotland); thallus grey, K�, Pd�;apothecia flat to slightly convex, to 1·5 mm diam., �immarginate; ascospores16–18(–19)�7–8 �m; epihymenium aeruginose (Cinereorufa-green), especiallyin K . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. caesium

Usually on more strongly basic rock, especially limestone; thallus white;apothecia smaller; epihymenium olivaceous, blue-black, or purple-brown(Macrocarpa-green or Atra-red) . . . . . . . . . . . . . . . . . . . . . . . . 6

6(5). Exciple and epihymenium K�; apothecial disc usually pruinose; thallus K+yellow, Pd+ orange (stictic acid) or rarely K+ red, Pd+ yellow (norsticticacid) . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. caeruleoalbum

Exciple K+ purple (Atra-red) . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

EcologyMost species are confined to either basic

or acidic rocks, although R. caesium, whichusually occurs on mildly basic rocks, alsooccurs on flushed or periodically inundatedacidic rocks. Similarly, R. lavatum usuallyoccurs on flushed or periodically inundatedacidic rocks but also occurs on mildly basicrocks.

ExcipleDetailed investigations of the excipular

structure in Rhizocarpon have not been madebut would probably yield some interestingresults. In this study, the exciple of R. cin-ereovirens is distinguished by being muchreduced, usually appearing thin and lightlypigmented in microscopic section, and hav-ing a central opaque (white) zone when

viewed under incident light, possibly due tothe presence of crystals of norstictic/sticticacid.


7(6). Epihymenium K+ purple; thallus K+ yellow, Pd+ orange (stictic acid present). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. chioneum

Epihymenium K�; thallus K�, Pd� (lichen substances absent) . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. expallescens

8(4). Thallus K+ red, Pd+ yellow (norstictic acid) . . . . . . . . . . . . . . . . . . 9Thallus K+ yellow, Pd+ orange (stictic acid) or K�, Pd� (no substances) . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

9(8). Ascospores small, 11·0–13·0�5·0–6·0 �m; epihymenium and exciple brown, K+purple (Atra-red); paraphysoids with well developed caps (not recorded from theBritish Isles) . . . . . . . . . . . . . . . . . . . . . . . . . . R. glaucescens

Ascospores larger; epihymenium greenish, not K+ purple; paraphysoids withoutwell developed caps; exciple brown, K+ purple or K� . . . . . . . . . . 10

10(9). Exciple poorly developed, not K+ purple; thallus cracked-areolate or of creamywhite bullate areoles; on disused metal mine spoil, montane rocks and coastalshingle . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. cinereovirens

Exciple well developed, K+ purple; thallus of dispersed, grey, bullate areoles.(Recorded only from Greenland) . . . . . . . . . . . . . . . . . R. discoense

11(8). Apothecia flat to slightly convex, to 1·5 mm diam., �immarginate; epihymeniumaeruginose (Cinereorufa-green), especially in K; thallus grey, K�, Pd�;ascospores 16–18(–19)�7–8 �m; usually on slightly basic or semi-inundatedacidic rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. caesium

Apothecia smaller; epihymenium blue-black, olivaceous or without pigment(�Macrocarpa-green) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

12(11). Ascospores >21 �m long, usually becoming brown when old . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. hochstetteri

Ascospores usually <20 �m long, rarely becoming brown when old . . . . . 13

13(12). Exciple pale in section, with an opaque medulla under incident light; paraphysoidtips blue-black, N+ red (Macrocarpa-green) . . . . . . . . R. cinereovirens

Exciple completely dark in section; paraphysoid tips brown, N� (Atra-brown),although bluish (N+ red) pigment (Macrocarpa-green) also often present in theepihymenium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

14(13). Thallus thin, olivaceous-brown, continuous, K�, Pd�; apothecia with thin,persistent exciple; Epihymenium hyaline (Macrocarpa-green usually absent);usually on boulders in deciduous woodlands but occasionally upland/montane

. . . . . . . . . . . . . . . . . . . . . . . . . R. infernulum f. sylvaticumThallus white, grey or brown, areolate, K+ yellow, Pd+ orange (stictic acid) or

K�, Pd� (no substances); apothecia with thicker exciple or occasionallyimmarginate. Epihymenium usually blue-black (Macrocarpa-green present); onexposed siliceous rocks . . . . . . . . . . . . R. infernulum f. infernulum

convoluted history of Rhizocarpon concretum. DrCoppins also corrected my Latin diagnoses. I thank DrsIrwin Brodo (Ottawa) & Tassilo Feuerer (Hamburg)for helpful discussion, and the US National ScienceFoundation (Award No. DBI-9808735—Alan Prather,PI)) that financed their visit to Michigan StateUniversity; Ralph Common (East Lansing) for hisexcellent photography; the directors and curators of

I acknowledge the receipt of an academic Scholarshipfrom the University of Sheffield which allowed me topursue my studies of the montane lichen vegetation ofthe British Isles and a ‘Small Ecological Projects’ grantfrom the British Ecological Society to cover expenses ofsubsequent visits to British herbaria. I am particularlygrateful to Dr Brian Coppins (Edinburgh) and ananonymous reviewer for assistance in elucidating the


E, BM, MICH and MSC for allowing me freeaccess to their herbaria, and Jutta Buschbom, StephenChambers, Vince Giavarini, Elisabeth Lay, and thecurators of BM, C, CANL, G, GB, H, L, MIN, TUR,and UPS for the loan of material. Professor MarkSeaward kindly provided the map of the Britishdistribution of R. caesium.

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Accepted for publication 27 August 2002

a revision of the species of the rhizocarpon hochstetteri ... · rhizocarpon discoense is shown to...

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