Micarea is a genus of lichen-forming fungi in the family Ectolechiaceae. The widely distributed genus contains 156 species and new species are described actively. Species in the genus are crustose lichens and their photobiont (the non-fungal organism) is a single-celled green alga. The genus was established by the Swedish mycologist Elias Fries in 1825. Micarea lichens are typically small and often overlooked, producing minute fruiting bodies that are usually whitish, grey, or bluish in colour. Many species reproduce both sexually through spores and asexually through specialised structures, and they are found on substrates ranging from tree bark and dead wood to rocks and even moss. The genus has a cosmopolitan distribution, with species recorded from Europe, Australasia, the Americas, Africa, and oceanic islands. Several species are of interest to researchers studying how shifts between different substrates and reproductive strategies drive the formation of new species.

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