Type: Ecuador. Galapagos Islands: Isla Santa Cruz, vicinity of Academy Bay, ca. 0.8 km E of Darwin Station, coastal zone, shore boulders just above high tide mark, on rock, 10-Apr-1976, Weber, W.A. s.n. & Lanier, J. (L-63675, COLO 297761–holotype; isotypes distributed as Weber, Lich. Exs. no. 500).
Description. Thallus saxicolous, thin to thick, rimose to rimose-areolate, areoles granular to densely verrucose or bullate; surface pale to deep yellowish green, yellowish beige or ochraceous (especially with prolonged storage in the herbarium), roughened, matt, epruinose or with a fine, pale yellowish pruina (KC/C+ orange), lacking soredia; prothallus mostly indistinct, but occasionally forming a blackish outline where different thalli meet. Apothecia numerous, dispersed, circular to barely undulate in outline, large, 0.5–1.5(–2.0) mm in diam., soon sessile and ±constricted below, distinctly lecanorine with prominent, persistent, entire to barely undulating, smooth, epruinose to barely yellowish pruinose margin, concolorous with the thallus; disc plane to ±convex, concolorous with the thallus, becoming beige to dull brown with age, with a fine, pale yellowish pruina (KC/C+ orange); hymenium hyaline, not inspersed or with few oil droplets; epihymenium with a diffuse, dull brown pigment (elachista-brown: dissolving in K, HCl± dull greenish, N−) and few to abundant minute crystals, mostly dissolving in K (residue of fine, rounded, reddish granules persistent, 0.5–1 μm); proper exciple thin, indistinct, with few small crystals; thalline exciple thick, distinctly corticate, with many small crystals that obscure a few larger ones, these often visible only when the small crystals are dissolved in K, but the large ones persist; subhymenium and hypothecium hyaline, inspersed with small to medium-sized oil droplets; ascospores 8/ascus, simple, ellipsoid to broadly ellipsoid, (6.9–)8.3–9.8(–10.3) × (3.9–)4.1–5.0(–5.9) μm (n = 30). Pycnidia immersed, conidia filiform, 13.7–22.5 × 1.0–1.2 μm (n = 5).
Chemistry.:P−, C+ orange, KC+ orange, K−, UV± dull to deep orange; with arthothelin [major], thiophanic acid [minor], 3-O-methylthiophanic acid [minor], isoarthothelin [minor]; [specimens examined with TLC: Bungartz, F. 4622 (CDS 28709), 5053 (CDS 29266), 5392 (CDS 29608), 9876 A (CDS 47214), Weber, W.A. s.n. & Lanier, J. (L-63675, COLO 297761–holotype)].
Ecology and distribution. Endemic to the Galapagos; one of the most common saxicolous species, also rarely growing on hardened wood, throughout all vegetation zones (coastal to high altitude dry), but most frequent in the coastal and dry zone, typically growing in exposed, sunny situations, occasionally also in sheltered habitats.
Notes. This Galapagos endemic is probably the most common saxicolous lichen throughout the entire archipelago. In the dry zone and along the coast its conspicuous yellow crusts typically cover huge areas. These tinted rocks can even be seen from afar, when approaching an island by boat. A specimen from Galapagos identical to L. pseudopinguis in the Tuckerman Herbarium (FH; sheet 2094) has been annotated in Tuckerman’s handwriting as “L. flavicunda”. The combination “Lecanora flavicunda” was, however, never published and Tuckerman’s annotation could also refer to Lecidea flavicunda Ach. [= Porpidia flavicunda (Ach.) Gowan], a very different taxon. In any case, the typewritten label of the specimen reads “L. subflava”. A packet with the type of Lecanora subflava Tuck. in FH (Fascicle no. 31, sheet no. 1944) contains two specimens, one (no. 167) from Cuba, which Tuckerman (1866) referred to as the type; it has a yellow beige thallus with orange beige apothecial discs; the thallus reacting K+ orange, C+ orange, UV+ orange, and P−. From this specimen I.M. Brodo prepared a permanent slide stained with lactophenol cotton blue (June 1973). These sections stained with lactophenol cotton blue appear to have polarilocular spores, but fresh sections do not confirm this observation. The spores are non-septate, simple, typical Lecanora spores. The material is similar, but clearly not identical with the saxicolous L. pseudopinguis. Lecanora subflava is corticolous, it has much smaller apothecia (max. 1 mm in diam.), a thalline exciple that contains only large and no small crystals, and it has ascospores ca. 9.5 × 6.5 μm.