Lecanora subcrenulata Müll. Arg. (1888: 533) MycoBank

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 : 56

Lecanora subcrenulata Müll. Arg. (1888: 533) MycoBank no. 389316

Type:— BRASIL. MINAS GERAËS: Morro de Itambé , sine dato, Puiggari, J. I. 2220 (G– holotype) .

( Fig. 13E–F )

Thallus saxicolous or rarely corticolous (in Galapagos known only from rock substrates), thin and often reduced, rimose to verrucose areolate; surface white to pale gray, roughened, matt, epruinose or with faint, whitish pruina, lacking soredia; prothallus white, weakly developed, typically indistinct. Apothecia sparse to numerous, ±isolated or in small groups and then deformed by mutual pressure, circular to very irregular in outline, often quite large, 0.5–1.7(–2.2) mm in diam., soon distinctly sessile and usually ±constricted at the base, distinctly lecanorine, margin soon crenate and often broadly undulating, epruinose, concolorous with the thallus; disc concave to ±plane or very weakly convex, pale greenish beige, darkening with age, becoming deep brownish beige, epruinose or faintly whitish pruinose; hymenium hyaline, not inspersed; epihymenium with crystals, almost hyaline to pallid yellowish brown (elachista -brown: dissolving in K, HCl± dull greenish, N−), both pigment and crystals soluble in K (chlarotera - type); proper exciple thin, indistinct, with abundant small crystals; thalline exciple thick, ±corticate, with many small crystals that obscure a few larger ones often visible only when the small crystals are dissolved in K and the large ones persist (melacarpella - type); hypothecium hyaline; ascospores 8/ascus, simple, narrowly to broadly ellipsoid, (8.9)–9.1–11.6– (12.9) × (4.0–)5.1–6.7(–6.9) µm (n = 20). Pycnidia not seen .

Chemistry: Thallus cortex including apothecial margin react P+ yellow, C−, KC−, K+ yellow, UV−; with atranorin [major], isonotatic acid [major], 4- O -methylhypoprotocetraric acid [minor], norisonotatic acid [minor], and 2’- O - methylperlatolic acid [major]; [specimen analyzed with TLC: Bungartz, F. 7617 ( CDS 38113)]. Guderley (1999) also reports ±chloroatranorin and ±usnic acid, but these substances were not detected in the Galapagos specimen.

Ecology and distribution: Neotropical ( Feige et al. 2000: Argentina, Brazil, Colombia, Peru, Uruguay, Venezuela), new to Ecuador and the Galapagos; a single specimen has so far been collected in the archipelago, from a bare basalt outcrop in the high altitude dry zone of Volcán Darwin.

Notes: This species is very distinctive because of its large, strongly undulate apothecia and scant thallus; superficially it thus closely resembles L. cactacea , a species that so far is known only from cacti (see comments above). The two species are chemically well distinguished: 4- O -methylhypoprotocetraric acid is characteristic for L. subcrenulata . It is a very conspicuous secondary metabolite, easily detected by TLC [the unusual chemistry previously discussed in detail by Feige et al. (2000)].

Specimen examined. ECUADOR. GALÁPAGOS: Isabela, Volcán Darwin, 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. 7617 ( CDS 38113 ) .

Figures

FIGURE 13. Species in the L. subfusca-group; superficially similar species with pale to dark brown apothecial disc and melacarpella- or allophana-type exciple (coarse and fine or fine crystals only). A–B. Lecanora darwiniana (Bungartz, F. 4859, CDS 29055–holotype). A. Thallus rimose, with abundant, coarsely granular soredia all across its surface and along the apothecial margin, apothecial disc deep brown, epruinose. B. Apothecial section: exciple with both coarse and fine crystals (melacarpella-type), epihymenium lacking crystals, brownish pigment insoluble in K (glabrata-type), exciple breaking apart into granular soredia (in water, DIC). C–D. Lecanora cactacea (Bungartz, F. 8178, CDS 40824–holotype). C. Thallus areolate verrucose, growing on the flaky surface of cactus pads, apothecia large, distinctly sessile, margin soon conspicuously fissured, disc pale to deep brown, with age occasionally blackened. D. Apothecial section (in water, DIC): exciple evenly yellow brown throughout, filled with abundant, minute crystals that completely dissolve in KOH (allophana- type), epihymenium yellowish brown, not dissolving in KOH, lacking crystals (glabrata-type). E–F. Lecanora subcrenulata (Bungartz, F. 7617, CDS 38113). E. Thallus saxicolous, areolate, with large, distinctly sessile apothecia, margin moderately to strongly undulate with age, disc pale orange-brown, epruinose. G. Apothecial section (in water, DIC): exciple with both coarse and fine crystals (melacarpella- type), epihymenium with minute crystals and brown pigment (chlarotera-type). Scales: A, C, & E = 5 mm; B, D & F = 100 µm.