Micarea

Micarea is a genus of lichenized fungi in the family Pilocarpaceae, order Lecanorales, within the class Lecanoromycetes of the Ascomycota. The members are crustose lichens that commonly grow on bark, wood, or rock, often forming a very thin, granular thallus that can be inconspicuous to the naked eye. The apothecia are usually small and numerous, frequently embedded in the thallus, and the ascospores are typically minute, often simple to one-septate. Because the thalli and fruiting bodies are tiny, distinguishing species commonly requires microscopic examination of spore morphology and tissue structure, as well as chemical tests or thin-layer chromatography to detect secondary metabolites.

Micarea species are widespread in temperate and boreal regions worldwide, occupying a diversity of substrates and microhabitats. Many members are microlichens, contributing to biodiversity on surfaces such as bark and rock where they may be overlooked in casual surveys. Ecologically, they participate in nutrient cycling within lichen communities and can be sensitive to environmental changes, making some species useful as indicators of air quality or habitat disturbance.

Taxonomically, Micarea is identified within Pilocarpaceae by a combination of morphological features, thallus texture, and chemical traits, though species delimitation often relies on detailed microscopy and chemistry, and increasingly molecular data. The genus includes numerous species, with several well-documented representatives such as Micarea prasina, a greenish crustose lichen commonly found on bark in many temperate forests. Ongoing research continues to refine the understanding of its species boundaries and distribution.