Acarospora

Acarospora is a genus of lichen-forming fungi in the family Acarosporaceae. The genus comprises crustose lichens that form areolate or patchy thalli on rocks and, less commonly, on bark. The thallus is usually corticate and crustose, with small polygonal areoles separated by fissures; color ranges from pale gray to dark brown, sometimes olive or reddish.

Apothecia are typically lecideine—disc-like fruiting bodies whose dark brown to black apothecia are embedded or marginal within the thallus. The asci contain typical lichen ascospores, and spore size and shape are used for species identification in combination with thallus features.

Acarospora species occur in a wide range of climates, but most are saxicolous, colonizing sun-exposed rock surfaces, including calcareous and siliceous substrates. They are common in deserts, mountain regions, and temperate zones, often as early colonizers on bare rock. Some species occur on bark but are less common.

Taxonomic placement has been revised with molecular data; the genus is part of the family Acarosporaceae, within lichen-forming fungi. Species delimitations are often subtle and require microscopic examination of the apothecia and spores and, increasingly, DNA data.

Acarospora is of interest to biogeographers and ecologists studying rock-dwelling lichens and primary succession.