Phylloblastia fortuita is a species of foliicolous (leaf-dwelling) lichen in the family Verrucariaceae.

Found in Western Europe and North America, it was formally described as a new species in 2009 by Esteve Llop and Antonio Gómez-Bolea.

The lichen, originally documented as occurring in the Mediterranean climate of the Iberian Peninsula, was reported from Marin County, California, in 2016.

[2] The greenish-grey thallus of Phylloblastia fortuita is thin and diffuse–somewhat similar to a cobweb.

The ascospores, which number eight per ascus, have an ellipsoid to spindle shape (fusiform), with usual dimensions of 20–35 by 5–9 μm.