Pyxine lilacina

About

Pyxine lilacina is a rare species of saxicolous (rock-dwelling), foliose lichen in the family Caliciaceae. Found in East Africa, it was scientifically described as a new species in 1975 by lichenologists Dougal Swinscow and Hildur Krog. The lichen has a brownish-grey to lilac-grey thallus that is tightly appressed to its substrate. The lobes comprising the thallus are flat, and have pseudocyphellae as well as patches of pruina. The thallus underside is black; the internal medulla is white. The lichen contains triterpenoid compounds as well as lichexanthone; the latter substance causes the lichen to fluoresce when lit with a long-wavelength UV light.

Summary from Wikipedia