Lecanora subimmergens Vain. (1921: 51) 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 : 56-57

Lecanora subimmergens Vain. (1921: 51) MycoBank no. 389344

Type:— JAPAN. KOZUKE PROVINCE: exact locality unknown, 19-Feb-1918, Yasuda, A. 355 ( TUR-V 6093 – holotype, BM – isotype) .

( Fig. 12E–F )

Thallus saxicolous, thick, rimose to rimose areolate, areoles granular to densely verrucose or bullate; surface white to pale gray, yellowish gray or pale brownish gray, roughened, matt, epruinose or with sparse, whitish pruina, lacking soredia; prothallus faintly developed, powdery arachnoid to compact, generally white, but occasionally blackening and forming a line where different thalli meet. Apothecia numerous, often densely aggregated, circular to slightly irregular in outline, often deformed by mutual pressure, 0.4–1.4 mm in diam., adnate to soon sessile and then ±constricted, distinctly lecanorine, margin persistent, entire to barely undulating, smooth, crenate or verruculose, epruinose to barely whitish pruinose, concolorous with the thallus, disc plane to ±convex, deep mahogany brown to almost black, epruinose to faintly whitish pruinose; hymenium hyaline, not inspersed; epihymenium lacking crystals, with a diffuse pale to dark reddish brown pigment (arnoldiana -brown: K+ dull brown, HCl+ reddish brown, N−), pigment persistent in K (glabrata - type); proper exciple thin, indistinct, with few crystals; thalline exciple thick, distinctly corticate, with many large crystals insoluble in K and sparse small crystals soluble in K (pulicaris - type); hypothecium hyaline; ascospores 8/ascus, simple, ellipsoid, (7.9)–9.5–12.8–(14.9) × (4.0–)4.9–6.5(–6.9) µm (n = 45). Pycnidia not seen.

Chemistry: Thallus cortex including apothecial margin P+ yellow, C−, KC−, K+ yellow; with atranorin [major], zeorin [major], unknown terpenes [minor], ±xanthone 54 [minor]; [specimen analyzed with TLC: Bungartz, F. 7600 ( CDS 38096)].

Ecology and distribution: Almost cosmopolitan (North and South America, Asia, Australia), new to Ecuador and the Galapagos; only few specimens were found on exposed rock outcrops in the humid and high-altitude dry zone of Volcán Alcedo, Isabela.

Notes: This species has not previously been reported for Galapagos ( Guderley 1999) and specimens growing on rock were initially identified as L. tropica ; the two taxa are very similar and might even be conspecific (see notes on L. tropica below).

Specimens examined. ECUADOR. GALÁPAGOS: Isabela, Volcán Alcedo, upper NNW-exposed slope inside the crater, 0˚27’27’’ S, 91˚7’23’’W, 1055 m alt., humid zone, open vegetation with Adianthus concinnum , and scattered shrubs of Tournefortia rufo-sericea among basalt rocks, basalt, on rock, 05-Mar-2006, Aptroot, A. 64893 ( CDS 31470); outer E-exposed slope just below the crater rim, 0˚25’17’’ S, 91˚5’8’’W, 1077 m alt., humid zone, basalt outcrops, SE-exposed slope with scattered shrubs of Tournefortia rufo-sericea , Opuntia insularis , Lantana peduncularis and occasional trees of Zanthoxylum fagara among basalt rubble, lava, on rock, 08-Mar-2006, Aptroot, A. 65154 ( CDS 31737); ca. 1.5 km from the southwestern crater rim, 0˚12’20.5’’ S, 91˚18’52.77’’W, 128 m alt., high altitude dry zone, basalt outcrop for the most part bare of vegetation, on rock, 14-Nov-2007, Bungartz, F. 7600 ( CDS 38096).

Figures

FIGURE 12. Species in the L. subfusca-group; superficially similar species with deep brown apothecial disc and pulicaris-type exciple (large crystals only). A–B. Lecanora schindleri (Weber, W. A. s.n., L-40337, COLO 188861). A. Thallus continuous to barely rimose with fimbriate whitish prothallus, apothecia adnate to sessile, margin entire, disc deep reddish brown to almost blackish brown, epruinose or with very faint, whitish pruina. B. Apothecial section (in water, DIC), exciple with abundant minute, soluble crystals obscuring few large, insoluble ones (melacarpella-type), epihymenium with reddish brown, insoluble pigment and minute soluble crystals (pulicaris-type). C– D. Lecanora tropica. C. Thallus rimose-areolate, slightly verrucose, delimited by a darkened prothallus line, apothecia adnate to sessile, margin entire to ±crenulate, disc deep reddish brown, epruinose (Bungartz, F. 8425, CDS 41071). D. Apothecial section (in water, DIC): exciple with conspicuous, large, insoluble crystals and few minute, soluble ones (pulicaris-type), epihymenium with insoluble brown pigment, lacking crystals (glabrata-type) (Dawson, E.Y. s.n., L-40089, COLO 188062). E–F. L. subimmergens (Bungartz, F. 7600, CDS 38096). E. Thallus areolate, apothecia adnate to sessile, margin entire, slightly undulate, disc dark reddish to blackish brown, epruinose. F. Apothecial section (in water, DIC): exciple with conspicuous, large, insoluble crystals and few minute, soluble ones (pulicaris-type), epihymenium with insoluble brown pigment, lacking crystals (glabrata-type). Scales: A, C & E = 5 mm; B, D & F = 100 µm.