Calicium pinicola

The lichen was first formally described as new to science in 1969 by Swedish lichenologist Leif Tibell, as Cyphelium pinicola.[2] Maria Prieto and Mats Wedin transferred it to the genus Calicium in 2016 following a molecular phylogenetics study of the Caliciaceae-Physciaceae clade.[3]

Calicium pinicola has a yellowish-green, warty (verrucose) thallus that is quite thin and sometimes partially immersed in the substrate. Its apothecia are black, sessile with a partial constriction at the base, and measure 0.4–0.6 mm in diameter. The ascospores, which number eight per ascus are ellipsoid with a single septum, and measure 13–17 by 7–9 μm.[2]

Calicium pinicola contains rhizocarpic acid, a lichen product that presents as small yellow crystals in the cortex).[2]

Calicium pinicola grows on decorticated wood, particularly that of Pinus sylvestris, but it has also been recorded on Betula and Larix. A preferred microhabitat is the dead twigs of living pine trees.[2]

In Switzerland, Calicium pinicola is threatened with extinction,[4] and it has been categorised as vulnerable in Italy.[5] Other countries from which it has been reported include Austria, Macedonia, the United States, Turkey,[6] and Kandalaksha in Arctic Russia.[2]