Lecanora atro-ocellata Bungartz, 2020

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 : 26-28

Lecanora atro-ocellata Bungartz sp. nov. MycoBank no. 833369

Diagnosis. Thallus deep yellow, similar in color to L. pseudopinguis , but differs in having subsquamulose areoles and deep olivaceous brown to bluish black apothecial discs.

Type:— ECUADOR. GALÁPAGOS: Isabela, Volcán Darwin, southwestern slope, above Tagus Cove, 0˚13’43.3’’ S, 91˚19’47.3’’W, 724 m alt., transition zone, SW-exposed lava flow of weathered AA-lava with scarce vegetation ( Macraea laricifolia , Dodonaea viscosa , Croton scouleri , Cordia revoluta and Jasminocereus thouarsii ), exposed basalt rock, 12-Nov-2007, Ertz, D. 11821 ( CDS 37180– holotype).

( Fig. 8A–C )

Thallus saxicolous, moderately thickened, areolate, of dispersed, rarely ±contiguous irregularly convex to somewhat granular, often slightly subsquamulose areoles; surface deep greenish yellow to greenish beige or yellowish ochraceous, ±roughened, matt, epruinose, lacking soredia, prothallus absent. Apothecia numerous, ±aggregated, circular to slightly irregular in outline, sometimes deforming one another, 0.2–0.6(–0.8) mm in diam., semi-immersed, emergent to adnate, eventually sessile and then ±constricted below, initially cryptolecanorine, but soon becoming lecanorine with persistent, crenate to strongly verruculose, epruinose margin, concolorous with the thallus; disc plane to ±convex, deep olivaceous brown to bluish black, appearing matt for its indistinct, hyaline pruina; hymenium hyaline, not inspersed; epihymenium ±granular, but lacking distinct crystals, with a diffuse, aeruginose pigment (cinereorufa -green: intensifying in K, HCl+ bluish green, N+ reddish violet); proper exciple thin, indistinct, with few small crystals; thalline exciple thick, distinctly corticate, with many large crystals not dissolving in K and sparse small crystals dissolving in K; hypothecium hyaline; ascospores 8/ascus, simple, broadly ellipsoid to subglobose, (7.8–)8.9–12.5(–18.6) × (3.9–)5.0–7.2(–8.8) µm (n = 45). Pycnidia not seen.

Chemistry: Thallus cortex including apothecial margin P−, C+ orange, KC+ orange, K−, UV− (dull or deep orange); with atranorin [major], arthothelin [major], isoarthothelin [minor]; [specimen analyzed with TLC: Bungartz, F. 6786 ( CDS 36205)].

Etymology: With its dark greenish black discs, the epithet atro-ocellata meaning “with small black eyes” seems appropriate; the hyphenation is used here in accordance with ICBN Art. 60.9.

Ecology and distribution: Known only from the Galapagos, from the transition through the humid to the high altitude dry zone, on steep rock surfaces (large boulders, steep cliffs), typically in ±sheltered, semi-shaded, rarely exposed to sunny habitats.

Notes: Because of the black apothecial discs, the species could at first glance be confused with Buellia mamillana (Tuck.) W.A. Weber , a species that initially has similar lecanorine apothecia becoming lecideine only with age. Thalli of L. atro-ocellata , however, are a much deeper yellow-ochraceous color and they are composed of discrete, distinctly separate, often dispersed and ±subsquamulose areoles. The areoles do not become elongated like those of Buellia straminea Tuck. , a species which is very similar in color, but always with distinctly lecideine apothecia. If examined with the microscope, both Buellia species are easily distinguished from L. atro-ocellata due to their pigmented, septate ascospores.

Among the Galapagos-species of Lecanora , L. pseudopinguis is most similar in color, but that species has significantly larger apothecia, with a disc never blackened and a more contiguous thallus.

Additional specimens examined (paratypes). ECUADOR. GALÁPAGOS: Isabela, Volcán Darwin, southwestern slope, above Tagus Cove, 0˚13’43.27’’ S, 91˚19’47.27’’W, 724 m alt., transition zone, SW-exposed lava flow of weathered AA-lava with scarce vegetation ( Macraea laricifolia , Dodonaea viscosa , Croton scouleri , Cordia revoluta and Jasminocereus thouarsii ), on rock, 12-Nov-2007, Bungartz, F. 7408 ( CDS 37895); 7427 ( CDS 37914); Ertz, D. 11806 ( CDS 37165); 11821 ( CDS 37180); ca. 1.5 km from the southwestern crater rim, 0˚12’20.5’’ S, 91˚18’52.77’’W, 1280 m alt., high altitude dry zone, basalt outcrop for the most part bare of vegetation, on rock, 14-Nov-2007, Bungartz, F. 7584 ( CDS 38080), 7593 ( CDS 38089); Volcán Sierra Negra, top of the northern crater rim, 0˚48’3’’ S, 91˚5’25.89’’W, 968 m alt., humid zone, SW-exposed basalt cliffs among dry vegetation of grasses and herbs, on rock, 08-Sep-2007, Bungartz, F. 6784 ( CDS 36203), 6776 ( CDS 36195), 6786 ( CDS 36205); Volcán Chico on the norteastern slope of Sierra Negra, 0˚46’56.77’’ S, 91˚6’4.298’’W, 938 m alt., transition zone, young lava flow with very scattered vegetation ( Macraea laricifolia , Darwiniothamnus tenuifolia ), on rock, 14-Aug-2008, Bungartz, F. 8166 ( CDS 40812).

Figures

FIGURE 8. Species in the L. pinguis-group. A–C. Lecanora atro-ocellata. A–B. Morphological variation A. General thallus aspect, pale yellow, discrete areoles, apothecia adnate to sessile, with thick, crenate margin and blackened, faintly pruinose disc (Bungartz, F. 7427, CDS 37914). B. Close-up of the thallus (Ertz, D. 11821, CDS 37180–holotype). C. Apothecial section (in water, DIC): exciple with large crystals, epihymenium aeruginose, in parts ±granular (Ertz, D. 11821, CDS 37180–holotype). D–G. Lecanora pseudopinguis. D–F. Morphological variation. D. Thallus flattened, rimose-areolate (Bungartz, F. 5194, CDS 29407). E. Thallus slightly convoluted (Bungartz, F. 7278, CDS 37762). F. Thallus gnarled, rimose-areolate, with fimbriate marginal areoles (Bungartz, F. 7772, CDS 38280). G. Apothecial section: exciple with pale brown cortex, packets of green photobionts inside, dispersed throughout with minute crystals (Bungartz, F.7278, CDS 37762). Scales: A, B, D & F = 5 mm; C & G = 100 µm; F = 10 µm.