Thallus saxicolous, placodioid leprose, i.e., developing upon a common, shared hypothallus, delimited by a thin prothallus forming an irregular to ±indistinctly lobed margin, but always lacking a distinct lip, not ‘crisped’(finkii-type sensu Lendemer 2011a); surface pale bluish gray, in the herbarium fading to pale whitish beige; hypothallus thin, arachnoid; rhizohyphae absent; granules ecorticate, ill-defined, powdery [(25–)40–50(–70) µm in diam., relatively uniform in size, occasionally aggregating in clusters (up to 150 µm)], generally loosely packed, typically with some protruding hyphae; photobiont green, coccoid, 7–14 μm in diam.
Spot tests and chemistry: P-, K± sordid yellow, KC+ red, C+ red, UV- (pale); lecanoric acid; Flakus & Kukwa (2007) also report angardianic/roccellic acids and 2–4 unidentified anthraquinones present in some, but not all specimens; these were not observed in the Galapagos material.
Distribution and ecology: Neotropical; new to Ecuador and the Galapagos, previously known only from Bolivia (Flakus & Kukwa 2007, Saag et al. 2009, Flakus et al. 2011); in the Galapagos currently known from a single collection: in a sheltered, shaded rock cove, at moderate elevation in the upper transition zone of Santa Cruz.
Notes: This is the only truly leprose Galapagos species with lecanoric acid, reacting C+ red/KC+ red. Its occurrence at relatively moderate elevation (583 m) is unexpected as the type of the species and subsequent collections were all collected at high elevation in the Andes (Flakus & Kukwa 2007, Flakus et al. 2011). In comparison with other Lepraria species known to contain lecanoric acid, the growth morphology of the Galapagos specimen best matches that of L. achariana. The Galapagos material lacks the anthraquinones reported from the type, but according to Flakus & Kukwa (2007) and Flakus et al. (2011) these substances are often sparse or absent and always confined to the lower part of the thallus, where the hyphae adhere to the substrate.
Differences to other species of this growth type are discussed under L. finkii.