Opegrapha physciaria

Opegrapha physciaria is a species of lichenicolous (lichen-dwelling) fungus in the family Opegraphaceae. It was first formally described as a new species in 1897 by Finnish lichenologist William Nylander, who placed it in the genus Lecidea. David Hawksworth and Brian J. Coppins transferred it to the genus Opegrapha in 1992.

The fungus produces apothecia (fruiting bodies) that are 0.02–0.3 wide and 0.15–0.21 mm tall. Its, which number eight per ascus, contain three septa and measure 12–17 by 4–6 μm. The fungus grows on the thallus of the foliose lichen species Xanthoria parietina. Opegrapha physciaria is similar to another related lichenicolous fungus, O. rupestris, but is distinguished by different ascospore dimensions (14–22 by 5–8 μm), and a different host (crustose Verrucariaceae species).

Opegrapha physciaria has been recorded from Europe and North America.