BACIDIA CAESIOVIRENS, A NEW LICHEN SPECIES FROM WESTERN EUROPE

Lichenologist 27(2): 91–98 (1995)

BACIDIA CAESIOVIRENS, A NEW LICHEN SPECIES FROM WESTERN EUROPE Stefan EKMAN* and Håkon HOLIEN‡

Abstract: Bacidia caesiovirens S. Ekman & Holien sp. nov. is described from Norway, and the British Isles. It occurs on trunks of deciduous trees in coastal forests. This species is usually sterile and is characterized by its conspicuously blue-green, granular thallus, which contains a bluish, N+ purple pigment. It is closely related to B. biatorina (Körb.) Vain., but differs from this species in a number of features apart from thallus pigmentation: the thallus granules are smaller, the amount of hyphal projections from the surface of the thallus granules is larger, and the internal pigmentation of the apothecia is different. Bacidia auerswaldii (Hepp ex Stizenb.) Mig. has a similarly granular thallus but differs from B. biatorina and B. caesiovirens in having wide, fusiform spores and smaller thallus granules. Bacidia absistens (Nyl.) Arnold has an internal apothecium pigmentation similar to B. caesiovirens, but differs in having a smooth thallus, and an abundance of minute crystals in the excipulum.

Introduction For several years, a conspicuously blue-green crustose lichen has been known in the coastal areas of Trøndelag, central Norway. It was never found with apothecia, but its granular thallus was reminiscent of that in Bacidia biatorina (Körb.) Vain. When studying material of B. biatorina from the British Isles, a number of collections, two of which were fertile, turned out to be this unidentified species. Examination of apothecial characteristics made it evident that it is really a close relative of B. biatorina. However, it is distinct from this species, differing in a number of respects. No suitable name has been found for this lichen and hence it is described here as a new species. We name it Bacidia caesiovirens due to the striking colour of the thallus. Materials and Methods All collections of Bacidia caesiovirens (in all c. 45 specimens) and a number of collections of B. biatorina, B. absistens, B. auerswaldii, and an undescribed North American species of Megalaria deposited in BG, E, GB, LD, and TRH were studied. Characteristics of the thallus and apothecia were studied on hand-cut sections or squash preparations mounted in water. The tholus of B. caesiovirens was studied in a 0·3% solution of iodine in lactic acid, following pretreatment with 10% KOH. Lichen substances were investigated using thin layer chromatography (TLC) (White & James 1985), and high performance thin layer chromatography (HPTLC) (Arup et al. 1993). The excipular structure of B. caesiovirens was studied using apothecial sections 15 ìm thick made with a Leitz Kryomat freezing microtome. The sections were treated with an 0·3% aqueous solution of sodium hypochlorite to bleach the pigments, which otherwise obscure part of the *Department of Systematic Botany, University of Lund, Östra Vallgatan 18–20, S–223 61 Lund, Sweden. ‡Department of Botany, Museum of Natural History and Archaeology, University of Trondheim, N–7004 Trondheim, Norway. 0024–2829/95/020091+08 $8.00/0

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excipulum. Microscopic preparations were studied and photographed in a Zeiss Axioskop interference contrast microscope with an MC 63 A microscope camera. Using 17 specimens of B. biatorina, 19 specimens of B. caesiovirens, six specimens of Bacidia auerswaldii (Hepp ex Stizenb.) Mig. (LD), and ten specimens of the undescribed species of Megalaria (BG, LD), the following null hypotheses were tested statistically: (1) (2) (3) (4) (5)

Bacidia caesiovirens and B biatorina do not differ in thallus granule size. Individuals of B. caesiovirens do not differ in thallus granule size. Individuals of B. biatorina do not differ in thallus granule size. Bacidia caesiovirens and B. auerswaldii do not differ in thallus granule size. Bacidia caesiovirens and the undescribed Megalaria do not differ in thallus granule size.

In each specimen, 10 granules were measured at 40 # magnification in a dissecting microscope. The measurements were then used in one-factor analyses of variance (‘one-factor ANOVAs’) and analyses of variance with nested design (‘nested ANOVAs’). Mean square values were used to calculate the hierarchical distribution of the variance. The analyses were performed with SuperANOVA (Abacus Concepts 1989) on a Macintosh LCIII with a floating point co-processor. Measurements are generally given as ‘[minimum value observed]—[maximum value observed]’, except granule size, which is given as ‘([minimum value observed]—) [lowest specimen arithmetic mean observed]—[arithmetic mean of all observations]—[highest specimen arithmetic mean observed](—[maximum value observed])’. S is the standard deviation of all observations. N is the number of specimens studied, and n is the number of observations per specimen, the total number of observations thus being N # n. The nomenclature of lichens and bryophytes is according to Santesson (1993) and Smith (1978, 1990), respectively.

The species Bacidia caesiovirens S. Ekman & Holien sp. nov. Bacidia biatorina (Körb.) Vain. similis sed thallus granulis minoribus (36–97 ìm) compositus, granula pigmentum caesium HNO3 purpurascens continentia; apothecia rarissima, fuscoatra ad atra, epithecium pigmentum atroviride dominans aliudque fuscum parcum continens. Typus: ‘Scotland, Argyll Main (V.C.98), Lorn, Taynuilt, by River Awe, c. 1 km SE of Inverawe House, 27/02.30, on Quercus, alt. c. 30 m, 21 September 1985, B. J. Coppins, 11313 (E— holotypus; fertile).

(Figs 1, 2A,B) Thallus crustose, thin to rather thick, bluish green, composed of discrete or aggregated granules, a very thin whitish to greyish blue endophloeodal hypothallus, and a&wide, endophloeodal, grey, greyish blue, or bluish black prothallus. Granules&globose, shortly cylindrical, or clavate, (36–)57–66– 77(–97) ìm wide (S=12, N=19, n=10), often&blue, dark greyish blue, or bluish black at the top; bluish pigment K+green, C", N+purple. Photobiont green, cells 4–9 ìm in diameter. Mycobiont loosely enclosing photobiont; at surface of granules composed of irregularly branching hyphae with thickwalled cells that are very different in size in relation to each other; forming numerous short or long hyphal projections. Apothecia very rare (observed in two collections), 0·6–1·0 mm wide, pure black, brownish black, or some (pigment deficient) purplish brown or grey-brown, epruinose, &plane with a rather thick, c. 90 ìm wide, persistent edge, which is level with or slightly raised above the disc. Excipulum proprium blackish brown in a thin distinct zone along the edge, pale brown inside except where streaks of blackish brown pigment reach from the edge to the interior,

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F. 1. Holotype of Bacidia caesiovirens, one of the two known fertile collections (B. J. Coppins, 11313–E). Linear magnification: # 27.

without crystals, in the interior consisting of heavily gelatinized, sparsely septate, richly branched hyphae with thin lumina, c. 1 ìm wide, along the edge consisting of &ellipsoid cells with lumina up to 4 ìm wide. Hypothecium very pale yellowish. Hymenium 81–99 ìm high, colourless except for the dark green epithecium; colouration caused by a dominating, evenly distributed dark greyish green pigment (K+pure green, C", N+purple with a precipitate of small blue crystals) and a sparsely occurring, patchily distributed blackish brown pigment (K+purplish, C", N+orange-red). Paraphyses unbranched or sparingly branched in the uppermost part, 1·2–1·6 ìm wide in midhymenium; apices not at all or only slightly thickened, 1·6–2·4 ìm wide, unpigmented or with a faint greyish hood. Asci cylindrical or narrowly clavate, with 8 spores. Tholus in iodine with a high, bluntly conoidal ocular chamber and a high, bluntly conoidal axial body, surrounded by an evenly dark blue zone. Spores acicular, straight, curved, or sigmoid, 46–72 ìm long, 2·5–3·7 ìm wide, 7–15-septate. Pycnidia not seen. Chemistry: Trace amounts of atranorin or no lichen substances detected. Ecology: Bacidia caesiovirens is a corticolous lichen on trunks of deciduous trees. The most common phorophytes are Quercus sp. and Sorbus aucuparia, but it has also been recorded on Alnus incana, Betula pubescens, Fraxinus excelsior and Populus tremula. In one rich Norwegian locality (Flatanger,

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F. 2. A, Surface view of thallus granule in Bacidia caesiovirens, showing short and long projections of hyphal ends (H. Holien, 5546–TRH). The projections from this granule are unusually numerous and long. B, Section of apothecium in B. caesiovirens (B. J. Coppins, 11313–E). C, Surface view of thallus granule in B. biatorina for comparison (U. Arup & S. Ekman, L504–LD). Note that projections are lacking and that the hyphae closely adhere to the granule. Scale: A & C=20 ìm, B=200 ìm.

Nord-Trøndelag) it was even found on young, smooth-barked trunks of Picea abies close to old trunks of Sorbus. Bacidia caesiovirens is a member of a lichen community almost entirely dominated by crustose lichens. At an early or mid-successional stage, probably leading to Lobarion as the climax, this community may be assigned to the ‘pre-Lobarion’ community (James et al. 1977). This community develops most pronouncedly in very humid and shaded habitats, especially in small ravines and on east- or north-facing slopes. Bacidia caesiovirens seems to be a good competitor with an aggressive, rapid growth and is very often found overgrowing liverworts (e.g., Frullania dilatata, F. fragilifolia, F. tamarisci, and Radula complanata). It also grows over other crustose lichens and over mosses (inter alia Pterigynandrum filiforme), as well as directly on the bark. On several occasions it has been found overgrowing thalli of B. absistens. In such cases the apothecia of the latter may easily be misinterpreted as belonging to B. caesiovirens. Under optimal conditions it may form large crusts up to several square decimetres, with few other lichens present. More often it is found as small patches among other lichens in species-rich communities. Faithful accompanying lichen species are B. absistens, Degelia plumbea, Lecidea atroviridis, Megalaria pulverea, Micarea cinerea, M. prasina, Ochrolechia szatalaensis, Pannaria rubiginosa, Pertusaria borealis and Ropalospora viridis. Among interesting and rare associates are Arthothelium norvegicum, B. biatorina, Lecanora cinereofusca, Mycoblastus caesius, Pannaria ignobilis, Pseudocyphellaria crocata, and Rinodina disjuncta.

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F. 3. Known world distribution of Bacidia caesiovirens.

Distribution: Bacidia caesiovirens is known from oceanic areas of western Norway, western Scotland, and the north part of Ireland (Fig. 3). In Norway, it is most frequently found in the coastal spruce forests of Namdalen and western parts of the Fosen peninsula, central Norway. Its altitudinal distribution reaches from sea level to about 240 m (West Ross, Scotland). Similar species: Bacidia caesiovirens belongs to Bacidia in the strict sense. It is closely related to B. biatorina (Körb.) Vain., a species that likewise occurs on deciduous trees in western Europe, although it is not as pronouncedly oceanic as B. caesiovirens. However, Bacidia caesiovirens and B. biatorina differ in a number of characters (Table 1): (1) Thallus pigmentation. The thallus of B. biatorina never contains the bluish pigment that gives B. caesiovirens its characteristic colour.

Dark orange-brown to black-brown

Acicular, less than 4 ìm wide

Dark greyish green (K+pure green, C", N+purple with a precipitate of small blue crystals) Dark brown (K+purplish, C", N+orange-red), patchily distributed No

Black or sometimes grey-brown to purple-brown (Fig. 1) Acicular, less than 4 ìm wide

Dominating pigment in epithecium and excipulum

Additional pigments in epithecium and excipulum

Excipulum internally with abundant minute crystals

Colour of apothecia

Spore shape

No

None

Dark brown (K+purplish, C", N+orange-red)

Few, except from granules adhering to the substratum (Fig. 2C)

Abundant, long or short (Fig. 2A)

Hyphal projections from granules

Brownish (N+orange), yellowish, or pale green, granular, granules (48–)79–87–107(–133) ìm wide

B. biatorina

Bluish green (N+purple), granular, granules (36–)57–66–77(–97) ìm

B. caesiovirens

Thallus

Character

Fusiform with blunt ends, 4–6 ìm wide

Black, rarely&purplish brown

No

None

Dark brown (K+purplish, C", N+orange-red)

Few, except from granules adhering to the substratum

Green-grey to brown-grey or grey-brown, granular, granules (36–)48–53–62 (–85) ìm wide

B. auerswaldii

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Acicular, less than 4 ìm wide

Black, rarely grey-brown

Yes

None

Dark greenish or purplish (K+pure green, C" N+purple with a precipitate of small blue crystals)

—

&Smooth, grey or greenish

B. absistens

T 1. Important characters to distinguish between Bacidia caesiovirens S. Ekman & Holien, B. biatorina (Körb.) Vainio, B. absistens (Nyl.) Arnold, and B. auerswaldii (Hepp ex Stizenb.) Mig.

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(2) Size of thallus granules. The variation in the size of a single thallus granule overlaps, but when an average of ten granules per individual is used, the variation is discontinuous. The difference between the species in granule size is statistically highly significant (nested ANOVA, individuals nested within species, df=1, F=96·7, (P=0·0001). (3) Amount of hyphal projections from the thallus granules (Fig. 2A, C). (4) Epithecium and excipulum pigmentation. The epithecium and excipulum edge of B. caesiovirens is dominated by a greenish pigment, but they also contain small patches with the same brown pigment that gives the epithecium and excipulum edge of B. biatorina a&dark brown colour. (5) Apothecium colour. The apothecia are often paler in B. biatorina than in B. caesiovirens. None of these differences are due to environmental modification, since B. caesiovirens and B. biatorina remain distinct even at the only known locality where they occur together (Stjørdal, Nord-Trøndelag, Norway). There are two further species of Bacidia that are similar to B. caesiovirens, namely B. auerswaldii (Hepp ex Stizenb.) Mig. and B. absistens (Nyl.) Arnold. Bacidia auerswaldii is similar to the other two species in having a granular thallus, and its apothecial pigmentation is basically the same as in B. biatorina. However, B. auerswaldii differs from both species in having smaller thallus granules and in having fusiform spores that are at least 4 ìm wide (Table 1). The difference between B. auerswaldii and B. caesiovirens in thallus granule size is statistically significant (nested ANOVA, individuals nested within species, df=1, F=37·9, P=0·0001). Furthermore, B. auerswaldii is a more southern species, occurring north to southern Sweden. Bacidia absistens and B. caesiovirens differ in a number of characters (Table 1), although their apothecia display similarities. In both species, the epithecium is dominated by a pigment that reacts K+green and N+purple, then fading and forming a precipitate of small blue crystals. In B. absistens, this pigment may display a greenish or purplish colour, but in the few apothecia of B. caesiovirens available for examination, only a greenish colour has been observed. In the coastal forests of British Columbia and Washington in western North America there is an apparently undescribed species of Megalaria that displays remarkable similarities with B. caesiovirens in thallus appearance. Sterile specimens may easily be mistaken for B. caesiovirens. The Megalaria sp. has a granular thallus of similar thickness, which contains the same bluish pigment as B. caesiovirens. Sometimes, it forms dark prothalli, just like B. caesiovirens. It is very similar to B. caesiovirens in hyphal anatomy. Furthermore, the granules are of the same shape and of similar size as B. caesiovirens, although slightly larger, (36–)69–76–83(–109) ìm. The variation in the size of the thallus granules overlaps with B. caesiovirens, both when a single thallus granule and an average of ten granules is used. However, the difference is statistically highly significant (nested ANOVA, individuals nested within species, df=1, F=26·0, P=0·0001). Apart from the granule size, Megalaria sp. differs from B. caesiovirens in often forming thin, grey areoles in addition to granules. The granules are formed on the surface of the areoles or directly on the hypothallus. Furthermore, Megalaria sp. always lack atranorin and produces apothecia more often than B. caesiovirens.

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Patterns of variation: Within B. caesiovirens there are no statistically significant differences between individuals in thallus granule size (one-factor ANOVA, df=18, F=1·61, P=0·06). As much as 94% of the total variance in this character is due to within-individual variation (the remainder being due to between-individual variation), which shows that in this character B. caesiovirens is a very homogeneous species unlikely to display any geographical separation. In B. biatorina, on the other hand, there are significant differences between individuals (one-factor ANOVA. df=16, F=2·28, P=0·005), but also in this species a large portion (89%) of the total variance in granule size is due to within-individual variation. Only a very small part of the betweenindividual variation in B. biatorina is likely to be due to geographical separation, since there are no significant differences between, on the one hand, the Scandinavian (N =9) and, on the other hand, the British specimens (N=8; nested ANOVA, individuals nested within geographic origin, df=1, F=0·16, P=0·69). Most of the between-individual variation is likely to be due to environmental response or to differences between age groups. Additional specimens examined: Only a selection of the Norwegian finds is listed. The specimens are sterile unless otherwise stated.—Norway: Hordaland: Tysnes, Tysnesøy, Beltestad, N-facing slope, 1993, Tønsberg 19193 & 19205 (BG); Os, Strøno, NE slope of hill, 1984, Tønsberg 8723 (BG); Lindås, W of lake Husdalsvatn, E slope of hill Håhaugen, Hjortåsen, 1984, Tønsberg 8621 (BG). Sør-Trøndelag: Rissa, along river Nordelva, 1990 & 1992, Holien 3984 & 4897 (TRH); Åfjord, NE-facing slope of Petrusfjellet, 1993, Holien 5784 (TRH). Nord-Trøndelag: Stjørdal, Bjørdalen, NW of Berg, 1991 & 1993, Holien 4198 & 5546 (TRH); Namdalseid, along brook Trettengbekken, 1990, Holien 3753 (TRH); Flatanger, E-facing slope W of Dalavatnet, 1993, Holien 5823 & 5828 & Ekman (TRH); Fosnes, by lake Salsvatnet, Gravvika in a ravine, 1992, Holien 5323 (TRH). Nordland: Brønnøy, NE-facing slope of Liaheia, 1992, Holien 5089 & 5099 a (TRH).—Scotland: V.C. 101, Kintyre: Ellary Woods, S of Loch Meadhonach, 1976, Coppins 2644 (E). V.C. 105, W. Ross: Coulin Forest, pinewood by Allt na Luib, 1984, Coppins 10561 & 10721 (E). V.C. 97 Westerness: N side of Loch Sunart, Salen, An Cnap, 1990, Coppins 13849 (E, fertile).—Ireland: V.C. H35, W. Donegal: Glenveagh National Park, woodland on SE shore of Lough Veagh (Beagh), 1991, Coppins 14707 & Fox (E). V.C. H40, Londonderry: c. 5·5 km SSW of Dungiven, Banagher Woods, Altnaheglish Glen, 1991, Coppins 14416, O’Dare & Andersson (E). We are grateful to Dr Brian J. Coppins, Edinburgh and Dr Tor Tønsberg, Bergen, for placing collections at our disposal, to Mr Per Lassen, Lund, for help with the Latin diagnosis, to Mr Arne A. Frisvoll, Trondheim, for determining the bryophytes, to Mr Per Fredriksen, Trondheim, for taking the holotype photograph and to Dr Ingvar Kärnefelt, Lund, for comments on the manuscript. R Abacus Concepts (1989) SuperANOVA. Berkeley, California: Abacus Concepts, Inc. Arup, U., Ekman, S., Lindblom, L. & Mattsson, J.-E. (1993) High performance thin layer chromatography (HPTLC), an improved technique for screening lichen substances. Lichenologist 25: 61–71. James, P. W., Hawksworth, D. L. & Rose, F. (1977) Lichen communities in the British Isles: a preliminary conspectus. In Lichen ecology (M. R. D. Seaward, ed.): 295–413. London: Academic Press. Santesson, R. (1993) The lichens and lichenicolous fungi of Sweden and Norway. Lund. Smith, A. J. E. (1978) The Moss Flora of Britain and Ireland. Cambridge: Cambridge University Press. Smith, A. J. E. (1990) The Liverworts of Britain and Ireland. Cambridge: Cambridge University Press. White, F. J. & James, P. W. (1985) A new guide to microchemical techniques for the identification of lichen substances. British Lichen Society Bulletin 57(suppl.): 1–41. Accepted for publication 4 June 1994