Micarea pauli is a species of corticolous and lignicolous (bark- and wood-dwelling), crustose lichen in the family Ectolechiaceae. It is only known to occur in Poland's Biaà Âowieà ¼a Forest.
The lichen was formally described as a new species in 2019 by Beata Guzow-Krzemià Âska, Ann à Âubek, and Martin Kukwa. The type specimen was collected by the third author from Biaà Âowieà ¼a Forest in Biaà Âowieà ¼a National Park (); there it was found growing on an Alnus glutinosa tree. The species epithet pauli refers to Polish lichenologist Paweà  Czarnota, who, according to the authors, is a "specialist in the genus who monographed it in Poland".
Micarea pauli has an indeterminate crustose thallus that grows within or on its bark substrate, appearing as a greenish film. The thallus, which lacks a prothallus, comprises tiny areoles about 0.1 mm in diameter that develop branched and coral-like (coralloid) isidia that are densely packed to form a nearly continuous layer over the thallus. Apothecia occur rarely; when present, they are beige with spots of grey pigment measuring up to 0.5 mm in diameter. Asci contains eight spores and measure 30âÂÂ35 by 9âÂÂ12 üm. The ascospores range in shape from ovoid, to ellipsoidal, to oblong, and have dimensions of 7âÂÂ13 by 3.5âÂÂ4.5 üm; some of them have a single septum. Micarea pauli contains methoxymicareic acid, a lichen product that can be detected using thin-layer chromatography.
Micarea aeruginoprasina and M. nigra are somewhat similar in morphology, but can be distinguished from M. pauli by differences in apothecial pigmentation.
Micarea pauli is only known to occur from a few locations in the Biaà Âowieà ¼a Forest. Most specimens have been recorded on the bark of Alnus glutinosa, but it has also been found on the bark of Tilia cordata and on decorticated wood.