Chrysothrix galapagoana

The lichen has a thallus composed of dispersed immature granules and larger mature granules. The mature granules range in size from 150 to 290 μm in diameter and have a pseudo-areolate appearance, often creating an illusion of distinct areoles. These granules are bright neon-yellow, pseudo-corticate, and ecorticate in smaller forms. Immature granules, sized 35–70 μm, form on the upper surfaces of these larger granules and eventually disperse, a feature that distinguishes C. galapagoana from similar species. The lichen contains a green coccoid algal photobiont, with cells measuring 7–10 μm in diameter. Apothecia and pycnidia have not been observed in this species. Chemically, the lichen primarily produces calycin, with pulvinic dilactone occasionally present in minor quantities. Standard chemical spot tests yield reactions as follows: P−, K+ (faintly reddish), C−, KC−, and UV−.

Chrysothrix galapagoana is currently known only from the Galápagos Islands, specifically from the islands of Española, Floreana, Isabela, San Cristóbal, and Santiago. The species grows on basalt boulders, rocks, and cliffs in semi-shaded to fully exposed locations, typically within the dry and lower transition vegetation zones. It occupies habitats ranging from near coastal areas to dry, open forests. Due to its restricted known range, it is considered endemic to the Galápagos archipelago. This species was initially listed as Chrysothrix aff. occidentalis in earlier inventories but was later recognized as a separate, distinct taxon due to its morphological and chemical uniqueness.

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