Monogr. Acarosp.: 65 (1929).

Basionym: Lecanora chrysops Tuck., Suppl. Enum. N. Amer. Lich.: 425 (1858).

Synonyms: Index Fungorum

Protolog: "Thallo crustaceo e squamulis subaggregatis rotundato-difformibus peltatis lobatis angulato-repandisve nitidus laete flavis (nunc albicantibus farinosis), apotheciis immersis disco nudo immarginato e rufo nigricante margine thallode tumidulo integerrimo cincto" fide Magnusson (1929: 64). Unfertig

Type locality: USA, South Carolina, Aiken, H. W. Ravenel 424 (FH)(Havard university) Data lacking. Lectotypification by Knudsen (2007: 9).

Type locality coordinates: Data lacking.

Molecular barcode: Data lacking.

Thallus: crustose, areoles dispersed, 0.3-1(-2) mm wide, thin, broadly attached, with a thinner rim that can become lobate in nutrient-rich habitats, rarely showing signs of vegetative division. Upper surface yellow, usually matt, sometimes pruinose especially in the center. Upper cortex is paraplectenchymatous, 20-40 µm thick, cells usually obscure, 1-3 µm wide. Algal layer even. Medulla prosoplectenchymatous. Apothecia usually one per areole; disc immersed, sometimes expanding to cover the whole areole or raised above the thallus surface in a parathecial crown concolorous with the thallus; disc dull red to yellowish red, rough, flat, concave or convex, + with interascal sterile plectenchyma. Hymenium hyaline below but yellowish to reddish brown in the upper part merging into the epihymenium, 70-110 µm tall. Paraphyses 1.5-2.0 µm diam. at mid-level, apices slightly expanded, usually reddish-brown. Asci 55-90 x 15-20 µm, clavate; ascospores 100-200 per ascus, usually narrowly ellipsoid 4-6 x 1.5-2.0(-2.5) µm. Pycnidia globose, 60-100 µm; conidia bacilliform, ca. 2 x 0.6 µm (Knudsen et al. 2008: 6).

Photobiont: Trebouxioid green alga.

Chemistry: Spot test negative. Rhizocarpic acid and/or epanorin (major) Only the epanorin chemotype appears to occur in the Galapagos Islands (Knudsen et al. 2008: 6).
Race I: Rhizocarpic acid (Knudsen et al. 2008: 6).
Race II: Epanorin (Knudsen et al. 2008: 6).

Ecology: On acid or volcanic rock. In harsh microhabitats the areoles are small and dispersed, but may be crowded and robust with well-developed lobes and large apothecia in nutrient-rich and moist habitats. From near sea level on Galapagos Islands to 2250 meters (Knudsen et al. 2008: 6).

Molecular data: Genbank

Distribution: Brazil, Columbia, the Galapagos Islands, Venezuela, El Salvador, Costa Rica, Mexico, Arizona, Rocky Mountains. Database

Note: An additional description in Magnusson (1929: 64).