Diagnosis. Characterized by a leproid thallus similar to Lecanora orosthea (Ach.) Ach. and L. perconfusa Printzen, but differs in lacking xanthones and in containing a conspicuous series of terpenes (the same terpenes as in Lecanora dissoluta Nyl.) in addition to usnic acid and zeorin.

Type: Ecuador. Galápagos: Santiago, along the trail from Bucanero to Jaboncillos, ca. 3 km SE of Bucanero, 0˚10’52’’S, 90˚48’33’’W, 362 m alt., transition zone, open woodland of large Bursera graveolens and smaller Psidium galapageium trees, grassland and basalt boulders in between, on lava, 22-Mar-2006, Aptroot, A. 65410 (CDS 31996–holotype).

Description. Thallus saxicolous, leproid, primary thallus indistinct, almost entirely dissolved into ecorticate, granular soredia on a byssoid arachnoid (‘fluffy’, ‘cottony’) hypothallus, effuse, not distinctly delimited, granules yellowish green, somewhat paler where eroded, ecorticate, ill-defined, mealy, very variable in size, rarely extremely finely farinose (4.5–)9.5–22(–42) μm in diam. especially where eroded, but usually larger, (82–)91–133(–142) μm in diam., occasionally irregularly aggregating, generally loosely packed, becoming covered by a coating of needle-shaped crystals after prolonged storage in the herbarium; photobiont green, coccoid, 6–12 μm in diam. Apothecia and pycnidia unknown.

Chemistry. Thallus cortex P−, C−, KC± yellowish brown, K± yellowish brown, UV−(dull); with usnic acid [major], zeorin [minor], and an extensive array of unidentified terpenes [minor] (the same, characteristic terpenes occur in Lecanora dissoluta and form a coating of needle-shaped crystals in old herbarium specimens, giving the thallus an overall moldy appearance) [specimens analyzed with TLC: Aptroot, A. 65410 (CDS 31996–holotype), 65401 (CDS 31987), 65588 (CDS 32177); Bungartz, F. 4860 (CDS 29056)].

Etymology. Named for its characteristic series of terpenes.

Ecology and Distribution. Known only from the Galapagos; all specimens occur on ±sheltered and shaded rocks
in the transition zone.

Notes. This species, formally described here, has previously been reported as Lecanora sp. by Bungartz et al. (2013) in their key to the leprose and leproid Galapagos lichens. Lecanora dissoluta contains the same set of terpenoids, but produces atranorin instead of usnic acid and an unknown pigment (Elix & Lumbsch 1996).