Lecanora marginata

Bungartz, Frank, Elix, John A. & Printzen, Christian, 2020, Lecanoroid lichens in the Galapagos Islands: the genera Lecanora, Protoparmeliopsis, and Vainionora (Lecanoraceae, Lecanoromycetes), Phytotaxa 431 (1), pp. 1-85 : 5-7

Lecanora marginata -group ( Figs. 1–5 )

The species assigned to this group share immersed to adnate, rarely sessile, biatorine to lecideine or cryptolecanorine apothecia, either without or with a thalline exciple barely differentiated from the surrounding thallus. Thalli are typically contiguous to rimose or rimose-areolate with a white to grey surface, sometimes with pale bluish, greenish or creamish tints, but without yellowish tinge. The thallus areoles often have fissures along their margins or are irregularly undulate to crenate. In well developed thalli the margins become distinctly serrate and closely interlocked. The chemistry is varied. Species typically produce atranorin and terpenoids, often anthraquinones (skyrin) and xanthones, rarely also usnic acid.

Lecanora austro-oceanica Hertel & Leuckert (1990: 224) MycoBank no. 124503 Type:— NEW ZEALAND. SOUTH ISLAND: Southland, Bluff, S of Ocean Beach, 46°36’S, 168°18’30”E, coastal rocks with Carbonea phaeostoma , Tephromela atra and Tylothallia pahiensis , 12-Feb-1985, Hertel, H. 30808 (M– holotype!; isotypes distributed as

Hertel, Lecideaceae Exsiccatae no. 224). ( Fig. 1A–B )

Thallus saxicolous, thick, contiguous, areolate, areoles with undulating edges, closely adjoining but not interlocked; surface white, dull, whitish pruinose, coarsely granular and roughened, lacking soredia; thallus margin delimited by a thin compact, blackened prothalline line, most pronounced where different thalli meet. Apothecia sparse to numerous, circular to weakly undulate, 0.2–1.2 mm in diam., adnate to just sessile, distinctly lecideine with a thin, shiny, epruinose, increasingly carbonized margin and a brownish to black, convex disc, densely covered by bluish grey pruina (C−, K−); hymenium hyaline, not inspersed, epihymenium with a diffuse aeruginose pigment (cinereorufa -green: intensifying in K, HCl+ bluish green, N+ reddish violet), with sparse clusters of small, dull brown granules that dissolve in K, and with few, large, irregular, hyaline crystals persistent in K, pigmentation and hyaline granules extending to the outer exciple; proper exciple initially weakly to moderately carbonized, pigmentation intensifying with age; thalline exciple absent; subhymenium and hypothecium hyaline to very faintly yellow; asci clavate, Lecanora - type, ascospores 8/ ascus, simple, subglobose to globose, (5.9–)6.8–8.6(–9.3) × (4.9–)5.2–7.1(–7.8) µm (n = 25). Pycnidia not seen.

Ecology and distribution: Previously reported from Tasmania and southern New Zealand; new to Ecuador and the Galapagos, where it is known from a single specimen collected at the shore.

Chemistry: Thallus cortex including apothecial pruina P+ yellow, K+ yellow, KC+ orange, C+ orange, UV+ bright orange; with atranorin [major], arthothelin [major], thiophanic acid [minor], zeorin [major], leucotylin [minor], unknown terpenes [minor]; [specimen analyzed with TLC: Weber, W.A. 151 (L-41000, COLO 190133)].

Notes: This species is superficially very similar to L. avium , but lacks areoles that are interlocked by their crenate margins and the thalli react C+/KC+ orange and fluoresce UV+ bright orange due to the presence of xanthones. Further, the ascospores of L. austro-oceanica are almost globose whereas those of L. avium are narrower (3.9-6.4 µm) and ellipsoid to broadly ellipsoid.

Previously Hertel (1989) reported L. subcoarctata from Galapagos based on the specimen re-determined here as L. austro-oceanica (Weber 151, L-41000, COLO 190133). Weber’s handwritten annotation of this material originally identifies the specimen as Lecidea chilena Zahlbr.We compared this specimen with exsiccatae of Lecanora subcoarctata from New Zealand ( Lecideaceae Exs. 146, COLO 409407, L-78791; Plantae Graecenses Lich. 405; COLO 375193, L-84332). Both differ from the Galapagos material collected by Weber. The New Zealand specimens of L. subcoarctata have an uneven verrucose to almost verruculose thallus composed of ±discrete, ±dispersed areoles whereas L. austro-oceanica from the Galapagos has an even, contiguous upper surface. Lecanora subcoarctata also lacks xanthones and therefore its thallus does not fluoresce nor does it react with C or KC.

Additional specimen examined. ECUADOR. GALÁPAGOS: Santa Cruz, vicinity of Academy Bay , along shore E of Research Station, coastal zone, aerohaline belt, 15-Feb-1964, Weber, W.A. 151 (L-41000, COLO 190133) .

Figures

FIGURE 1. Species in the L. marginata-group. A–B. Lecanora austro-oceanica (Weber 151, L-41000, COLO 190133). A. Thallus areolate with coarse surface, apothecia adnate with coarse grayish pruina. B. Apothecial section [in water, Differential Interference Contrast (DIC)]: outer exciple aeruginose, epihymenium dull brown. C–F. Lecanora avium. C–E. Morphological variation. C. Thallus areolate, delimited by a black prothallus, apothecia adnate, lecideine, disc with greenish yellow pruina (Bungartz, F. 10228, CDS 47647). D. Thallus, areolate, with erumpent pustulate granular soralia tinged dark bluish gray (Bungartz, F. 7280, CDS 37764). E. Thallus areoles with distinctly crenate margin, apothecia adnate, lecideine, disc with greenish yellow pruina (Bungartz, F. 6411, CDS 34626).F.Apothecial section [in water, DIC]: outer exciple aeruginose, epihymenium dull brown (Bungartz, F. 6411, CDS 34626). Scales:A, C, D & E = 5 mm; B & F = 100 µm.

FIGURE 2. Species in the L. marginata-group. A–D. Morphological variation of Lecanora austrosorediosa. A–B. Bungartz, F.4398, CDS 28483–holotype. A. Whitish gray, rimose-areolate thallus with smooth surface and fimbriate margin, apothecia adnate to barely sessile, biatorine, pallid, dark-tinged to sordid-blackened, soralia pustulate, with white granular soredia. B. Pale grey, rimose-areolate thallus with smooth surface and fimbriate margin, apothecia adnate to barely sessile, biatorine, pallid, soralia pustulate, with white granular soredia. C–D. Cream-white rimose-areolate thallus with coarse surface, pustulate soralia with white granular soredia, individual thalli delimited by blackened prothallus lines (Bungartz, F. 6426, CDS 34641). C. Part of the specimen with black apothecia appearing ‘lecideine’, their margin covered in grayish white pruina. D. Part of the specimen with pallid biatorine apothecia. E–G. Anatomy of L. austrosorediosa (Bungartz, F. 4398, CDS 28483–holotype). E. Section of dark-tinged, biatorine apothecium, outermost exciple and epihymenium with black pigment [in KOH, crystals dissolved, Differential Interference Contrast (DIC)]. F. Section of pallid, biatorine apothecium (in water, abundantly inspersed by minute crystals, DIC). G. Lecanora-type asci, tholus with wide, apically open, unstained central cone and deeply stained ascus flanks (in Lugol’s iodine, DIC). Scales: A, B, C & D = 5 mm; E & F = 100 µm; G = 15 µm.

FIGURE 3. Species in the L. marginata-group. A–B. Lecanora legalloana (Bungartz, F. 9366, CDS 46653). A. Rimose-areolate thallus composed of interlocked, crenate areoles, with immersed, deep reddish brown apothecia. B. Apothecial section with deep brown epihymenium, exciple with few large and abundant minute crystals. C–D. Lecanora oreinoides (Bungartz, F. 6781, CDS 36200). C. Thallus areolate, apothecia immersed, black. D. Apothecial section: exciple barely differentiated from surrounding thallus, epihymenium aeruginose. E–F. Lecanora subimmersa (Bungartz, F. 6311, CDS 34523). E. Rimose-areolate thallus composed of interlocked, crenate areoles, with immersed, deep reddish brown apothecia. F. Apothecial section with deep brown epihymenium, exciple with few large and abundant minute crystals, barely differentiated from surrounding thallus. Scales: A, C & E = 5 mm; B, D & E = 100 µm.

FIGURE 4. Species in the L. marginata-group. A–F. Lecanora prosecha. A–B. Esorediate specimen (Bungartz, F. 5633, CDS 33258). A. Thallus of distinctly crenate areoles with deeply immersed, cryptolecanorine, dark reddish-brown to blackened apothecia. B. Apothecial section (in water, DIC): exciple indistinct from surrounding thallus, epihymenium pale brown. C–F. Morphological variation of sorediate thalli. C. General growth aspect of the rimose, pale pinkish gray thallus (Bungartz, F. 6968, CDS 36472–holotype). D. Close-up of thick rimose pale pinkish gray thallus with sublobate margins, pustulate soralia with coarsely granular whitish to pale green soredia (Bungartz, F. 8675, CDS 41321). E. Sorediate thallus with immersed, cryptolecanorine apothecia (Bungartz, F. 8675, CDS 41321). F. Rimose pale gray thallus in parts tinged by reddish iron-oxides, pustulate soralia mostly eroded, leaving circular scars (Bungartz, F. 4848, CDS 29024). Scales: A, C, D, E & F = 5 mm; B = 100 µm.

FIGURE 5. Species in the L. marginata-group. A–B. Lecanora sp. 1 (Aptroot, A. 64396, CDS 30962). A. Rimose-areolate thallus of abundant pycnidia and serrately interlocking fissures. B. filiform conidia. Scales: A, = 5 mm; B = 10 µm.