127 Mycological Progress 2(2): 127–136, May 2003 Caloplaca erodens [sect. Pyrenodesmia], a new lichen species from Italy with an unusual thallus type Mauro TRETIACH1,*, Daniela PINNA2, and Martin GRUBE3 Caloplaca erodens is a new species of sect. Pyrenodesmia, characterised by an orbicular, sorediate, bluish-grey thallus which is endolithic but emerges at the periphery with a white, K-, obscurely lobate prothallus. The species is frequent on calcareous outcrops and walls of isolated churches and ruins of the Central Apennines (Sibillini, Gran Sasso), where it may occur in large monospecific populations, from 1000 to 2500 m asl., and is also known from dry sites of the southern Alps. It has been found with apothecia only in the type locality, being predominantly sterile. The reproduction of this lichen is evidently linked to the release of fragments of clusters of photobiont cells and mycobiont hyphae which are continuously exposed with the dissolution of the substratum. Readily distinguished from the apparently similar endolithic C. alociza (which is characterised by numerous apothecia, black, K+ purple prothallus, and esorediate thallus), C. erodens probably belongs to the C. circumalbata complex, whose taxa are always epilithic but have a white, K- prothallus. The phylogenetic position of the new species within sect. Pyrenodesmia as inferred by ITS sequences of the nuclear ribosomal DNA is shortly discussed. Taxonomic novelty: Caloplaca erodens Tretiach, Pinna et Grube T he growth of endolithic lichens on stone monuments is a problem which, despite its frequency, has been considered only in the last decades by researchers working on cultural heritage conservation (ASCASO & WIERZCHOS 1995, BLÁZQUEZ, CALVET & VENDRELL 1995, CARBALLAL et al. 2001, EDWARDS et al. 1994). As these organisms are actively involved in the weathering processes of the substratum (BACHMANN 1919, FRY 1922, DOPPELBAUR 1959, GEHRMANN-JANSSEN 1995, PINNA, SALVADORI & TRETIACH 1998), studies on their anatomy and ecology are providing important information to solve conservation problems (PINNA & SALVADORI 2000). In the present work, however, the novelty consists in the discovery of a new species, which was previously unnoticed probably because it is almost always sterile. In 1990 the second author was asked to identify a bluishgrey crust which covered the facade and the perimetre walls of the sanctuary of Macereto (Visso, Mts. Sibillini, Central Italy; Fig. 1), at that time undergoing a restoration managed by Ministry for Cultural Heritage. Interestingly, the crust was observed only on the church and nearby buildings, not on the Dipartimento di Biologia, Università di Trieste, Via Giorgieri 10, I34127 Trieste, Italy. 2 Soprintendenza per il Patrimonio Storico-Artistico, Via Belle Arti 56, I-40126 Bologna, Italy. 3 Institut für Botanik, Karl-Franzens-Universität Graz, Holteigasse 6, A-8010 Graz, Austria. * Corresponding author: Prof. Dr Mauro Tretiach, Dipartimento di Biologia, Via L. Giorgieri 10, I-34127 Trieste, Italy. Phone: +39 040 558 3886; fax +39 040 568 855. E-mail: tretiach@univ.trieste.it 1 surrounding natural outcrops, although they are of the same rock type as the walls: a massive calcarenite (Grillini, Pinna & Rossi Manaresi, unpubl.). For obvious reasons, only a limited quantity of material could be sampled. A first series of laboratory examinations showed that the “crust”, consisting of clusters of green algae surrounded by inflated, appressed hyphae with a grey, K+ violet pigment, belonged to a sterile lichen. PINNA & SALVADORI (2000) demonstrated the strong, harmful deteriorative capability of this organism, able to dissolve the stone at the centre of its thallus for a depth of several millimeters and forming, with ageing, confluent, moniliform depressions. The restorers removed the lichen from the church almost completely, but in the meantime the authors collected it – unfortunately always in sterile conditions – in several localities in central Italy, mainly on the walls of isolated churches and ruins. Only once was a single, badly developed, black, K+ violet apothecium found, containing a few, abortive polar-diblastic spores, and therefore the connection of this lichen to Caloplaca sect. Pyrenodesmia could be made (TRETIACH & PINNA 2000). Unfortunately, no permanent slides were prepared, and the comparison with other taxa of this section remained based on a few hand-written notes. In summer 2001, a very large population of this lichen was found on some natural outcrops of Mt. Sirente, and five fertile thalli were collected. All together, only c. fifty apothecia were counted, most of them sterile, but enough, however, to compare their carpological and sporological characters with those of additional taxa of Caloplaca sect. Pyrenodesmia studied in the meantime. It became evident that the lichen, found also in dry © DGfM 2003 128 Caloplaca erodens sp. nova Tab. 1. Specimens sequenced in this study, their locality data and Genbank accession numbers Species Specimen Caloplaca alociza Caloplaca alociza Slovenia, Sneznik, SE Mali Sneznik, 04.10.1997, leg. A. Wilfling [3417] and U. Arup (GZU). Slovenia, Sneznik, W of the peak, 04.10.1997, leg. A. Wilfling [3642] and U. Arup (GZU). AY313973 AY313972 Caloplaca chalybaea Italy, Campania, between M. Porco and M. La Gallinola, 16.4.2000, leg. P.L. Nimis and M. Tretiach (TSB 32110). Austria, Styria, Niedere Tauern, Planneralm, 13.9.1993, leg. A. Wilfling [318] and Möslinger (GZU). Italy, Marche, Sibillini Mts., 6.6.1999, leg. M. Tretiach (TSB 30970). Austria, Steirisches Randgebirge, Stubalpe, Wölkerkogel, 13.08.1993, leg. A. Wilfling [2323] (GZU). AY313975 Caloplaca chalybaea Caloplaca chalybaea Caloplaca chalybaea Genbank Nr. AY313970 AY313974 AY313971 Caloplaca erodens Italy, Abruzzo, prov. L’Aquila, Rovere, 23.6.2001, leg. M. Tretiach and D. Pinna (isotype, GZU). AY313977 Caloplaca obscurella Caloplaca obscurella Italy, Campania, Passo di Miralago, 15.4.2000, leg. P.L. Nimis and M. Tretiach (TSB 32037). Italy, Marche, Lago di Fiastra, 10.8.1999, leg. P.L. Nimis (TSB 31133). AY313977 AY313976 Caloplaca peliophylla Mexico, Baja California Norte, Guadalupe Island, 4.1.1996, leg. C.M. Wetmore [75893] (GZU). AY313965 Caloplaca variabilis Caloplaca variabilis Italia, Valle d’Aosta, Passo del Piccolo S. Bernardo, 9.1997, leg. P.L. Nimis (TSB 29427). Russia, Lake Baikal, mouth of river Sharma, on moss (!), 19.7.1997, leg. P.L. Nimis and M. Tretiach (TSB 28963). Crete, Nom. Rethimnio, Agia Galini, 16.5.1997, leg. H. Mayrhofer [13809] and Ertl (GZU). Italy, Molise, Monti del Matese, 16.4. 2000, leg. P.L. Nimis and M. Tretiach (TSB 32594). AY313966 AY313967 Caloplaca variabilis Caloplaca variabilis sites of the southern Alps, differs notably from the other species of Pyrenodesmia exhaustively treated in a monograph by WUNDER (1974). Its formal description is provided below, together with some critical notes on some other taxa of the same section. Material and methods Specimens collected by the authors and preserved in TSB and further material, obtained on loan from G, GZU, L, M, MOD, NAP, RO, UPS, VER, W, WU (acronyms of herbaria according to HOLMGREN, HOLMGREN & BARNETT 1990), were studied. Measurements were made on hand cut sections and squash preparations mounted in glycerine or in water. Ascospores, hamathecial filaments and other structures were measured at 1000x magnification. Measurements are given as: (mean-SD) - mean - (mean+SD) (max.). Permanent slides, mounted in glycerin or lactophenol-cotton blue (after treatment with 1 M HCl) according to VOLKMANN-KOHLMEYER & KOHLMEYER (1996), are preserved in the collection of the senior author. A Zeiss Axioplan compound microscope was used for micrographs of squashes and hand-made sections of ascomata, and a digital photocamera for habit photographs. Polished cross-sections of colonised rocks were obtained after embedding the samples in a polyester resin (New Basic). They were stained with Periodic Acid Schiff (PAS), according to WHITLACH & JOHNSON (1974), and with ortho-toluidine-blue, and observed under stereo- and reflecting microscopes. For habit photographs, samples were sputter-coated with gold under vacuum using an Edwards Sputter Coater © DGfM 2003 AY313969 AY313968 S150B, and investigated with a scanning electron microscope (SEM) (Philips SEM 505). The morphology of hyphae was observed in samples treated with 1 M HCl, in order to dissolve the calcareous rock, and washed several times in tap water. The resulting biomass was stained with lactophenol-cotton blue, mounted in glycerin and observed with the optical microscope. The standardised method of thin layer chromatography (TLC) (e.g. CULBERSON & AMMANN 1979) was employed for checking the presence of lichen substances; three solvent systems (A, C, and G) were used. An investigation of the phylogenetic position of the new species was carried out using ITS sequences of the nuclear ribosomal DNA. Approximately 5 x 5 mm of the thallus of the new species was scraped off the rock for DNA-isolation according to the protocol of CUBERO et al. (1999). A horizontal section (c. 50 x 50 x 20 µm) of the hymenia of all other species studied in sect. Pyrenodesmia was used directly for PCR, except in Caloplaca peliophylla where a fragment of the thallus was used. PCR and sequencing followed ARUP & GRUBE (1999), and the alignment was produced automatically using BioEdit 5.0.6 (HALL 1999). The specimens used for molecular analyses are presented with their Genbank numbers in Tab. 1. For the following species, additional sequences were retrieved from Genbank and added to the alignment: Caloplaca demissa (AF353962, AF353960), C. cerina (AF353960), C. chlorina (AF353959), C. variabilis (AF353963). Caloplaca cerina and C. chlorina were used as outgroups for the subsequent phylogenetic analyses. The phylogenetic hypothesis was constructed using a Bayesian approach as implemented in the program MrBayes (HUELSENBECK & RONQUIST 2001). The general time rever- 129 Mycological Progress 2(2) / 2003 sible substitution model with among-site variation (GTR + γ, rates for variable site were drawn from a gamma distribution with 4 discrete categories) was used for likelihood calculations. The Markov Chain Monte Carlo (MCMC) analysis was run for 1000000 generations, with 4 chains starting from a random tree, and using the default temperature of 0.2. Every hundredth tree was sampled, while the first 50000 generations were discarded as burn-in. A consensus phylogram based on mean branch lengths was calculated with the sumt command. The tree with posterior probabilities of topologies higher than 50 % is presented in Fig. 18. Nomenclature of lichens follows NIMIS (2000). Taxa studied for comparison Caloplaca circumalbata (Delile) Wunder var. circumalbata: EGYPT, „In deserto aegypt. Wadi Cherese“, leg. G. Schweinfurth (M - isotype of Blastenia melanocarpa Müll. Arg.). Ibid., Wadi Nehich, leg. G. Schweinfurth (M). Ibid., Wadi Na-umieh, leg. G. Schweinfurth (M). Ibid., Gebel Cheschen, leg. G. Schweinfurth (M). „Ad saxa calcarea deserti prope Bir Ammam“, leg. G. Ehrenberg (G - lectotype of Callopisma aegyptiacum γ depauperatum Müll. Arg.). „Basse Egypte“, Mars 1880, leg. W. Barbey (G - holotype of Callopisma interveniens Müll. Arg.). – TUNISIA, NW of Gafsa, Djebel ben Younes, 270–300 m, 18.04.1968, leg. J. Poelt, det. H. Wunder (GZU). Road Sbeitla-Sfax, near Faid, 16 km W of Sidi-Bou-Zid, 18.04.1968, leg. J. Poelt, det. H. Wunder (GZU). – GREECE, Rhodi, S of Rhodi, 2,5 km N of Phaliraki, 20 m, 08.09.1983, leg. J. Poelt (GZU). – Caloplaca circumalbata var. candida (Stiz.) Wunder: SPAIN, Almeria, Serra Alhamilla, S of Nijar (25 km NE of Almeria), 02.08.1969, leg. H. Hertel, det. H. Wunder (M). Greece, Agina island, coast near Agia Marina, 15.04.1971, leg. J. Poelt, det. H. Wunder (GZU). Attika, near Atene, Likavito, Lykabettos, 04.04.1971, leg. J. Poelt, det. H. Wunder (GZU). Ibid., Imittos, NW of the monastery of Kesariani, 05.06.1971, leg. J. Poelt, det. H. Wunder (GZU). Tunisia, 3 km SW Thibar, 12.04.1968, leg. J. Poelt, det. H. Wunder (GZU). – Caloplaca alociza (A. Massal.) Migula: ITALY, Ad saxa in op. Avesa (M. Ongarine), s.d., leg. A. Massalongo (VER - lectotype of Biatorina alociza A. Massal.). – GERMANY, „An umherliegenden Steinen bei Obereichstätt“, leg. F. Arnold (M, lectotype of C. variabilis f. acrustacea Müll. Arg.). Jena, Mühltal, IX.1860, leg. Ahles (L - lectotype of Catillaria fraudulenta Körb.). Jura, „Jachhausen oberhalb Riedenburg im Altmühltal, VIII.1858, leg. F. Arnold (M - holotype of Biatorina albopruinosa Arnold). Croatia, „Gravosa“, s.d., leg. Weis (L - lectotype of Blastenia paragoga Körb.). – GREECE, Epirus, PeristeriSpitze, 2290 m, s.d., leg. E.V. Halacsy (holotype of C. intercedens (Trevis.) Steiner in Halacsy var. albomarginata Steiner in Halacsy). Results Caloplaca erodens Tretiach, Pinna et Grube sp. nova Figs. 1-16 hoc loco Thallus crustaceus, pro maxima parte endolithicus, in parte centrali sorediatus, griseocaeruleus vel violaceus, depressus, prothallo albido, epilithico, obscure lobato, ad 0.8 mm lato limitatus, algas virides cellulis 13.4–15.7–18.0(23.0) µm in diametro continens. Soralia diffusa sorediis griseis, K+ violaceis, N+ violaceis, C+ rubro-violaceis, c. 43–56–69(75) µm in diametro. Apothecia rarissima, sessilia, c. 0.2–0.25–0.3(0.4) mm in diametro, disco griseocaeruleo vel nigro, sparse pruinoso; margo thallinus evolutus, albidus, algas continens. Hymenium ad 50–60 µm altum, hyalinum; hypothecium incolore. Paraphyses simplices vel parce ramosae, laxae, saepe capitatae, apicibus usque ad 4–5 µm latis, pigmento griseo tectis, K+ violaceo, N+ violaceo, C+ rubro-violaceo. Asci (4)6–8-spori, clavati, typi „Teloschistes“ dicti. Ascosporae hyalinae, polardiblasticae, ellipsoideae, 10–11–12(19) x 6–7–8(9) µm, septo 3–4(5) µm longo. Conidiomata ignota. Ad saxa calcarea vel dolomiticola Italiae Peninsularis et Alpium Citeriorum. Caloplaca alociza similis, sed ab ea differt thallo sorediato prelunque sterili et margine albido, K-. Typus: Italia, Abruzzo, prov. L’Aquila, Rovere, 1440 m, massi calcarei presso la rocca diroccata, frequentissima e con apoteci, 23.06.2001, M. Tretiach & D. Pinna. Holotype (TSB 34131), Isotypes (GZU, M, UPS, herb. D. Pinna), further sterile isotypes will be distributed in a forthcoming fascicle of A. Vezda’s Lichenes rariores exsiccati). Additional specimens examined ITALY, Abruzzo, Prov. L’Aquila, Gran Sasso, below Corno Piccolo, 2350 m asl., dolomite, 09.08.1996, leg. P.L. Nimis and M. Tretiach (TSB 24708); below Rocca di Cambio, S. Lucia Abbey, c. 1300 m asl., limestone, 23.06.01, leg. M. Tretiach and D. Pinna (TSB 34129); Rocca di Mezzo, bell tower, 1280 m asl., limestone, 23.06.01, leg. M. Tretiach and D. Pinna (TSB 34130); Rocca Calascio, near the castle, 1400–1450 m asl., 06.04.1997, leg. P.L. Nimis and M. Tretiach (TSB 26368); Ovindoli, loc. Rovere, c. 1400 m asl., limestone, 15.07.1994, leg. D. Pinna (TSB 19755, 28640). Marche, Prov. Macerata, sanctuary of Macereto (Visso), c. 1000 m asl., calcarenite, 16.04.1994, leg. D. Pinna and M. Tretiach (TSB 31268); ibid. 06.06.1999, leg. M. Tretiach and D. Pinna (TSB 34937); road between Visso and Passo di Gualdo, Castelsantángelo, below Gualdo, ruins of a small church, c. 1000 m asl., 06.06.1999, leg. M. Tretiach and D. Pinna (TSB 34936). Piedmont, Prov. Cuneo, Alpi Cozie, ridge SE above Colle Valcavera, ca. 2470 m asl., limestone, 23.07.00, leg. P.L. Nimis and M. Tretiach (TSB 34524, 34527). Trentino, Prov. Trento, M. Bondone, Dosso d’Abramo, 2040 m asl., 10.2002, leg. J. Nascimbene (TSB 35420). Valle d’Aosta, Prov. Aosta, Monte Bianco (Mont Blanc) group, Val Veny W of Courmayeur, ridge W above Rifugio E. Soldini, ca. 2250 m asl., boulders of Jurassic limestone, 30. 07. 2001, leg. M. Tretiach (TSB 35422). Umbria, Prov. Perugia, Val Castoriana, church of S. Salvatore, c. 700 m asl., 06.06.1999, M. Tretiach and D. Pinna (not collected). Veneto, Prov. Vicenza, M. Grappa, Città di Roccia, 1600 m asl., 10.2002, leg. J. Nascimbene (TSB 35421). Prov. Belluno, M. Faverghera, Botanical Garden, 1550 m asl., 08.10.2002, leg. J. Nascimbene (TSB 35419, CLU). Thallus crustose, orbicular, up to 6–8 cm diam. (Fig. 2), in the central part euendolithic (sensu GOLUBIC, FRIEDMAN & SCHNEIDER 1981), ecorticate, sorediate, bluish-grey to violaceous, depressed, delimited at the periphery by a whitish, K-, epilithic, obscurely lobate prothallus, c. 0.25–0.50(0.80) mm thick (Figs. 4,7). Photobiont green, protococcoid, cells 13.4– 15.7–18.0(23) µm diam (n=50). Soralia diffuse on the thallus surface, consisting of grey, K+ violaceous soredia, c. 43–56– 69(75) µm diam (Fig. 15), formed by small, irregular clusters of photobiont cells surrounded by appressed, inflated hyphal cells, c. 6–7(8) x 4–5 µm (Fig. 16), which emerge from the rock surface (Fig. 8). Ascomata apothecia, extremely rare, © DGfM 2003 130 slightly pruinose, marginate (Fig. 6), often irregularly shaped or immature (Fig. 5), up to c. 0.2–0.25–0.3(0.4) mm diam.; disc bluish-grey to almost black, thalline margin present (Fig. 9). Exciple distinct, thick, coherent in K, formed by strands of hyphae with irregularly ellipsoidal cells; outer part of the exciple dark grey or grey-green, inner part of the exciple with minute crystals persisting in N. Hymenium up to 60–70 µm high, I+ strongly blue. Hypothecium hyaline. Hamathecium of paraphyses, generally simple or slightly branched, apices swollen, up to 4–5 µm diam., pigmented as the outer part of the excipulum (Figs. 11,12). Asci (4)6–8-spored, clavate, Teloschistes-type (Fig. 13). Ascospores hyaline, polardiblastic, non-halonate, ellipsoid, 10–11–12(19) x 6– 7.0–8(9) µm (n = 39; 20 apothecia examined) (Figs. 10, 14). Conidiomata unknown. Chemistry Grey, acetone-insoluble pigment of epithecium, outer layer of excipulum and exposed parts of thallus K+ violaceous, C+ red-violet, N+ vivid violaceous (Sedifolia-grey sensu MEYER & PRINTZEN 2000: 581). No lichen substances detected by TLC. Etymology The epithet refers to the noteworthy deteriorative capability of this lichen. Ecology and distribution The new species is found in rather dry sites, at altitudes between 1000 and 2500 m asl., in the montane and subalpine belts of Apennines and southern Alps (Fig. 17). In some of these localities, Caloplaca erodens is relatively frequent, growing on subvertical surfaces of sunny rock walls and boulders of limestone and dolomite. Phytosociological relevés carried out in sites where C. erodens was particularly common are reported in Tab. 2. The lichen is frequently associated with common crustose epi- or endolithic species such as Acarospora glaucocarpa, Aspicilia calcarea, Caloplaca saxicola, Candelariella aurella, Diplotomma epipolium, Lecanora crenularia, L. muralis, Rinodina immersa, and R. bischoffii. This community looks like a mosaic of yellow-orange (C. saxicola, C. flavescens), bluish-grey (C. erodens) and light grey (heavily pruinose thalli of Lecanora muralis and Diplotomma epipolium) spots. However, C. erodens often forms almost Caloplaca erodens sp. nova monospecific populations. At higher altitudes, the species was found with C. coccinea and Xanthoria elegans. Caloplaca erodens should be looked for in the calcareous districts of other xerothermic valleys elsewhere in the Alps and in the montane belt of the Mediterranean region. Critical remarks The thallus organisation of Caloplaca erodens in cross section differs considerably from that of other endolithic lichens studied so far by the authors (PINNA, SALVADORI & TRETIACH 1998, TRETIACH & MODENESI 1999). In those organisms the photobiont cells typically form small, irregular, solitary clusters arranged in bores formed by dissolution of the rock, and are covered by an „outer layer“ of more or less densely conglutinated hyphae, often embedded by small crystals of CaCO3 („lithocortex“ sensu PINNA, SALVADORI & TRETIACH 1998; see also DOPPELBAUR 1959, Abb. 1). In C. erodens this „outer layer“ is absent, and the clusters of photobiont cells and appressed, inflated hyphae, emerge directly from the substratum (Figs. 8, 15); being pigmented, they give to the thallus a typical bluish-grey to violaceous colour, certainly unusual among endolithic lichens. When it became evident that the crust on the facade of the sanctuary of Macereto was actually the thallus of a lichen, we considered that it might belong to a trivial endolithic species whose unusual morphology was caused by some chemicalphysical peculiarities of calcarenite: with its dissolution, the upper thallus layer would be continuously exposed and lost, thus delaying sexual maturity and causing the formation of the typical depression of the central, older part of the lichen. However, in a subsequent survey, we observed on the same rock other lichens with „normal“ endolithic thalli growing side by side with our lichen (e.g. Rinodina immersa, R. bischoffii: see relevés of Tab. 2), and emerging as islets from the surrounding thalli of C. erodens (as the Verrucuria sp. of Fig. 3). We concluded therefore that calcarenite has only a limited influence on the morphology of our lichen. Furthermore, with the discovery of samples occurring on other rocks (for instance the hard, compact, crystalline limestone at the sites in Piedmont and Aosta Valley), it became evident that the dissolving of the rock is related to the strong deteriorative capability of this lichen more than to the chemical-physical properties of the substratum, as already suggested by PINNA & SALVADORI (2000). A strong dissolution of the rock, coupled by the ab- Figs. 1-8. Caloplaca erodens. Lichen communities with Caloplaca erodens (Figs. 1-2): on the left column of the entrance to the sanctuary of Macereto, where the species was observed for the first time (Fig. 1), and on a calcareous outcrop in the type locality (Fig. 2); the species is recognisable by the characteristic white prothallus. Large thallus surrounding an emerging Verrucaria sp. colonized by C. polycarpa (arrowhead) (Fig. 3; photo: J. Nascimbene). Closer view of two orbicular thalli (Fig. 4, isotype). Young (Fig. 5) and mature (Fig. 6) apothecia (holotype); the erosion of the substratum is visible. Fingerprint left by two died thalli on the rock (Fig. 7). Polished cross section showing clusters of algae intermingled with hyphae emerging from the substratum (Fig. 8). Scale bar = 5 cm (Fig. 2), 12 mm (Fig. 3), 8 mm (Fig. 4), 0.5 mm (Fig. 5), 0.3 mm (Figs. 6-7), 0.1 mm (Fig. 8). © DGfM 2003 Mycological Progress 2(1) / 2003 131 © DGfM 2003 132 © DGfM 2003 Caloplaca erodens sp. nova 133 Mycological Progress 2(1) / 2003 Nr. relevé Exposure Area (sq. dm) Cover (%) height above ground (cm) Caloplaca erodens Caloplaca saxicola Aspicilia calcarea Lecanora crenularia Rinodina immersa Candelariella aurella Diplotomma epipolium Lecanora muralis Candelariella medians Caloplaca polycarpa Caloplaca flavescens Kiliasia athallina Rinodina dubyana Caloplaca arenaria Caloplaca erythrocarpa Lecania turicensis Rinodina bischoffi Physcia adscendens Verrucaria fuscula Aspicilia radiosa Lecanora agardhiana Acarospora fuscata Caloplaca velana Xanthoria elegans Caloplaca variabilis Placocarpus schaereri 1 SW 12 50 20 2 WSW 3 90 60 3 WSW 5 90 70 4 WSW 5 60 70 5 SW 16 80 150 6 WSW 4 75 120 7 WSW 4 95 50 8 S 2 95 60 9 SE 6 70 40 10 SE 5 90 80 11 S 6 95 80 12 S 6 85 120 2 + 1 3 + 1 + 3 2 + + + + + 1 1 2 + + 4 r 2 + r + r r 1 3 r r 3 + 2 4 3 + + + + + r + + + 2 + + 1 + 1 + + + + 1 + r + + + frequency Tab. 2. Phytosociological relevés of lichen communities dominated by Caloplaca erodens V IV IV IV III III III III 1 + + + + r + + + r + 1 + + r + + + + r + + + + r r + + 1 + + + + + + + + + + + + + Localities of relevés: 1–5: walls of the sanctuary of Macereto, 1000 m; 6–7: ruins of small church near Gualdo, 1000 m; 8, 10–12: Rovere, calcareous outcrops, 1440 m; 9: Sibillini Mts.; between Sassotetto and Bolognola, calcareous outcrops, 1350 m. Other species frequently observed with Caloplaca erodens: C. cirrochroa and C. inconnexa (Rocca Calascio); C. decipiens (church of S. Salvatore, valle Castoriana); Tephromela atra var. calcarea and Lecanora sulphurea (Rovere). sence of a true lithocortex sensu PINNA, SALVADORI & TRETIACH (1998), is occasionally observed also in some forms of C. alociza (WUNDER [1974: 46] efficaciously wrote: „[…] die Gesteinsoberfläche an solchen Stellen porös verändert, wie aufgetrieben.“), with the difference that in this case the depression, in the form of a deep furrow, is formed at the periphery of the thallus („thallus […] profunde decussatus“: JATTA 1910: 400; see also MASSALONGO 1855: 42). These forms of C. alociza are always richly fertile (and esorediate), and therefore the „neothenic“ hypothesis explaining the low fertility of C. erodens can be probably rejected. Reproductive biology Caloplaca erodens is almost always sterile. Pycnidia are unknown and the apothecia of the few fertile thalli collected so far are often badly developed, with most producing abortive or irregularly shaped spores. Notwithstanding this, the lichen colonises large surfaces (as in the case of the facade of the sanctuary of Macereto and at the type locality), forming monospecific populations, probably due to very effective vegetative reproduction. The most obvious means is via clusters of algae surrounded by hyphae that protrude from the substratum and are presumably detached when the calcite crystals Figs. 9-16. Anatomical features of Caloplaca erodens (holotype). Margin of apothecium with algae in the excipulum (Fig. 9). Immature spores (Fig. 10). Tips of paraphyses (Fig. 11). Single paraphysis (Fig. 12). Young ascus (Fig. 13). Mature spores (Fig. 14). Closer view of the algal clusters of Fig. 8 (Fig. 15). Photobiont cell surrounded by inflated hyphae, stained by LPCB (Fig. 16). Scale bar = 50 µm (Fig. 9), 20 µm (Fig. 15), 10 µm (Figs. 10-13, 16). © DGfM 2003 134 are progressively dissolved. It may be questioned if these structures, rather irregular in size and shape, are to be considered true soredia, i.e. symbiotic propagules which derive from the proliferation of both algal and medullary layers (BÜDEL & SCHEIDDEGER 1996), or parasoredia, which are formed from clumps of disintegrating cortical and photobiont material (see CODOGNO, POELT & PUNTILLO 1989). C. erodens seems to be the first endolithic lichen known to reproduce in this way. Systematic remarks Within sect. Pyrenodesmia, only two endolithic species were accepted by WUNDER (1974), Caloplaca alociza and C. cretensis. A third taxon, C. agardhiana, related to C. alociza and considered by WUNDER (1974) to be a synonym of the latter, has been considered by many authors to be a further good species, characterised by the absence of crystals in the hymenium (see e.g. CLAUZADE & ROUX 1985). All these taxa typically occur on hard limestone and dolomite in exposed sites. Caloplaca cretensis is well-characterised by the yelloworange crystals, reacting K+ purplish-red, deposited in the epipsamma, which are intermingled with, and often obscured by the dark, K+ violet pigments typical of the Pyrenodesmia group (WUNDER 1974, MEYER & PRINTZEN 2000). Although mostly coastal, at least in Italy (NIMIS & TRETIACH 1999), this species also may form an epilithic thallus and is evidently not closely related to our taxon. The euendolithic C. alociza, considered by ROUX (1981) to be a characteristic species of Verrucarietalia parmigerae associations, is frequently found in open habitats from the warmest regions of southern Scandinavia (SANTESSON 1993) to the Mediterranean zone where it is particularly common (WUNDER 1974). It usually has a black, K+ purple prothallus and numerous pycnidia, more frequent along the thallus margin, and epruinose to heavily pruinose apothecia. In this species, the peripheral part of the thallus often forms a furrow, as in many other euendolithic lichens (see PINNA, SALVADORI & TRETIACH 1998, TRETIACH & MODENESI 1999), and does not show the characteristic depression in the central part of the thallus, typical of C. erodens. For many years, the authors of this paper wrongly considered the latter taxon as an aberrant form of C. alociza s.lat. and therefore studied the large collections filed under this name in GZU (85 specimens), MOD (15), NAP (3), and TSB (68). However, we never found any specimens with the characters of C. erodens, or even intermediate forms, although it is not unequivocally dismissed that some of the specimens of C. alociza „à thalle violacé“ cited by ROUX (1981) might belong to C. erodens. In our opinion, the relatives of the new species should be searched for in an other group of sect. Pyrenodesmia, the so-called C. circumalbata complex (WUNDER 1974), which has a more southern distribution, being frequent in the Southern Mediterranean basin and the Middle East, and reaching the innermost regions of Afghanistan (WUNDER 1974: 60). Caloplaca circumalbata, characterised by a usually well-developed, white prothallus © DGfM 2003 Caloplaca erodens sp. nova (from which its specific epithet derives), comprises at least four varieties, none of which, however, have a hemi- or euendolithic growth-form. When searching for available names, we examined the type material of some taxa referred by WUNDER (1974) to C. circumalbata because some of the features reported in their original diagnosis accord with those of C. erodens, namely the „poorly developed“ or „endolithic“ thallus (e.g. Blastenia melanocarpa Müll. Arg., Callopisma aegyptiacum γ depauperatum Müll. Arg., C. interveniens Müll. Arg., Caloplaca aegyptiaca var. circinans Steiner). However, we agree with WUNDER (1974) that these taxa are only aberrant forms of C. circumalbata resulting from damage caused by animals or wind-borne sand grains, and are of no taxonomic value. The type material of C. agardhiana var. granuligera, a taxon described by STEINER (1919) from Santorini (Greece), and possibly related to our lichen, could not be traced in W (U. Passauer, pers. comm.). Caloplaca ayachina, described by Werner within sect. Pyrenodesmia in the same year of Wunder’s monograph, has an epilithic thallus and different spores (WERNER 1974). These observations are partly confirmed by the results of the phylogenetic analysis shown in Fig. 18. The consensus tree indicates that C. erodens can be a member of sect. Pyrenodesmia. Using C. cerina and C. chlorina as outgroups, Caloplaca demissa turns out at a basal position in sect. Pyrenodesmia. Caloplaca obscurella, a corticolous, sorediate species is here the sister clade of a number of rock inhabiting species. In our analysis, the sequence of the type specimen of C. erodens is clearly supported at the base of this group, without indication that it would form a monophyletic group with C. alociza. The thallus growth-form does not correlate with the results obtained with the analysis of ITS sequences. In fact, the crustose epilithic C. chalybaea and the euendolithic C. alociza, which are well supported as groups, are nested in a group that also includes the crustose C. variabilis and C. peliophylla, a North American species with lobulate thalli (WETMORE 1994). Caloplaca variabilis, a highly polymorphic species (CLAUZADE & ROUX 1985), is genetically heterogeneous, and probably consists of several taxa, which might deserve to be treated at specific rank. From this analysis it seems clear, however, that C. erodens is outside the large complex of C. variabilis, and thus the previous hypothesis that the relatives of the new species should be searched for in the C. circumalbata complex is supported. Unfortunately, no fresh material of C. circumalbata was available for this study, and therefore the relationship between C. erodens and the latter species remains to be ascertained. Acknowledgements We are in debts with several fellow lichenologists who helped us in several ways during these years. U. Arup, J. Hafellner, H. Mayrhofer, P. Navarro-Rosinés, P.L. Nimis, C. Roux, C. 135 Mycological Progress 2(1) / 2003 Wetmore, and the late J. Poelt kindly examined sterile specimens of the new species, and discussed with the senior author possible relationships. The curators of GZU, G, L, M, MOD, NAP, RO, UPS, VER, W, WU, and J. Nascimbene are thanked for sending material in their care. We are grateful to J. Hafellner and C. Roux for providing rare literature and reading critically the manuscript, and to G. Kantvilas for improving the language. This study was partially funded by M.I.U.R. to P.L. 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