Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: crustose, dispersed-verrucose to verruculose or continuous to nearly byssoid, ecorticate; prothallus: not visible or black surface: yellowish white to yellowish gray or whitish gray, epruinose, with an indistinct margin, esorediate Apothecia: sessile, 0.2-0.5(-0.8) mm in diam., lecanorine disc: pale to dark red-brown, epruinose margin: concolorous with the thallus, thick, verrucose to verruculose, without a parathecial ring amphithecium: present, with numerous algae, with large and small crystals, corticate; cortex: hyaline, interspersed, slightly thickened basally, c. 15 µm thick laterally and 15-20 µm thick basally parathecium: hyaline, 10-15 µm thick, with numerous small crystals soluble in K epihymenium: reddish brown, 10-15 µm thick, pigmentation not altered in K, without crystals hymenium: hyaline, clear, 65-95 µm tall; paraphyses: sparingly branched and not to slightly thickened (up to 2.5 µm wide) apically; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 11.5-17 x 6.5-9 µm Spot test: thallus and apothecial margin K+ yellow, C+ orange, KC+ orange, P+ yellowish orange Secondary metabolites: atranorin (major), chloroatranorin (minor), chodatin (major), demethylchodatin (submajor), 3-O-methylthiophanic acid (minor), thiophanic acid (minor) and zeorin (major). Substrate and ecology: on bark World distribution: pantropical, known from rainforest edges, savannahs and gallery forests throughout the tropics Sonoran distribution: Baja California Sur and Chihuahua. Notes: Lecanora tropica is easily recognized by its small apothecia with a red-brown apothecial disc, the egranulose epihymenium, large amphithecial crystal, and te prsence of the chodatin chemsyndrome. Similar species in the area studied include L. neonashii and L. pseudargentata. The differences are discussed under these species. This is the first record of L. tropica from North America.
Type: Colombia (“Nova Granata”). Gualivá Province: Villeta, 1200 m, sine dato, Lindig, A. s.n. [H-Nyl 27567a–lectotype selected by Lumbsch (1994)].
Description.Thallus corticolous, 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 scarce, whitish pruina, lacking soredia; prothallus weakly 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 with persistent, entire, even to barely undulating, smooth, crenate or strongly verruculose, epruinose to sparsely whitish pruinose margin, concolorous with the thallus; disc plane to ±convex, deep mahogany brown, epruinose to sparsely whitish pruinose; hymenium hyaline, not inspersed; epihymenium lacking crystals, with a diffuse reddish brown pigment (arnoldiana-brown: K+ dull brown, HCl+ reddish brown, N−), pigment persistent in K (glabrata-type); properexciple thin, indistinct, with few crystals insoluble in K; thallineexciple 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, narrowly ellipsoid to broadly ellipsoid, (9.9)–14.4–13.3–(14.9) × (5.0–)5.2–6.8(–6.9) μm (n = 45). Pycnidia not seen.
Chemistry. Thallus cortex including apothecial margin P+ yellow, C− or C+ yellow to orange, KC− or KC+yellow to orange, K+ yellow, UV− (all Galapagos specimens are UV−, but specimens with xanthones react C/KC+yellow to yellow orange); with atranorin [major], ±zeorin [major], ±3-O-methylthiophanic acid [minor], thiophanic acid [major], ±unknown terpene [trace]; [specimen analyzed with TLC: Bungartz, F. 7192 (CDS 37676)]. Guderley (1999) reports additional ±chloroatranorin, ±chodatin, ±demethylchodatin, and ±other unidentified xanthones.
Ecology and distribution. Pantropical, first reported from the Galapagos by Guderley (1999); a moderately common species in the coastal, dry and lower transition zone of the islands, most common on Bursera graveolens, also on a few other native trees and shrubs.
Notes. This corticolous species appears extremely similar to the saxicolous L. subimmergens. However, thiophanic acid has not been detected in L. subimmergens.