Purple Pitted-stone Lichen

Bagliettoa marmorea is a species of saxicolous (rock-dwelling), crustose lichen in the family Verrucariaceae. It is endolithic on calcareous rocks, meaning it grows under and around the rock crystals. The colour of the lichen is purple to pink, although sometimes it is grey with purple pigments visible only around the perithecia. It does not have a shield-shaped involucrellum, which is typical of several other species in genus Bagliettoa. The excipulum (the rim of tissue around the ascomata) measures 0.2–0.3 mm in diameter and lacks colour other than the upper part, which is purple. Ascospores are 13–30 by 9–15 μm.

Bagliettoa marmorea is widespread in Europe. It has also been recorded from North America, although it is not certain if this represents a distinct species.