verrucaria

Verrucaria is a genus of lichen-forming fungi in the family Verrucariaceae. It comprises a large number of crustose lichens that grow on rocks, typically on calcareous substrates such as limestone and dolostone, though some species occur on damp rock faces or, less commonly, on bark. The name derives from Latin verruca, meaning wart, a reference to the warty appearance of many forms.

Morphology: Species in Verrucaria form a crustose thallus that is often inconspicuous and ranges in color from gray to olive-green to black. Many species bear embedded perithecia—disc- or wart-like fruiting bodies that appear as dark spots on the thallus. The perithecia open by a small ostiole, and the asci contain multiple ascospores. The extensive variation in thallus texture and fruiting body morphology makes species-level identification challenging without microscopic examination.

Ecology and distribution: Verrucaria is cosmopolitan, with a higher diversity in temperate regions. They are primarily saxicolous, inhabiting rocky surfaces on cliffs, outcrops, and rock walls; calcareous rocks are especially favorable. Some species live on damp rocks near streams or in moist rock crevices. They contribute to rock surface biodiversity and are used in studies of calcareous rock ecosystems and, in some cases, air quality as part of broader lichen communities.

Taxonomy and identification: The genus is defined by a crustose, perithecioid growth form within Verrucariaceae. Species identification usually requires examination of the perithecia, spore size and morphology, and, in many cases, chemical tests.