| Caliciaceae | |
|---|---|
| |
| Calicium viride | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Caliciales |
| Family: | Caliciaceae Chevall. (1826) |
| Type genus | |
| Calicium Pers. (1794)
| |
| Synonyms[1] | |
| |
The Caliciaceae are a family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. Although the family has had its classification changed several times throughout its taxonomic history, the use of modern molecular phylogenetic methods have helped to establish its current placement in the order Caliciales. Caliciaceae contains 39 genera and about 670 species. The largest genus is Buellia, with around 300 species; there are more than a dozen genera that contain only a single species.
Most Caliciaceae grow on bark, dead wood, or rocks. Some members of this family, particularly those of the type genus, Calicium, are characterized by the presence of thin-walled and short-lasting asci (spore-bearing cells) and a mazaedium, which is an accumulation of loose, maturing spores covering the surface of the fruiting body. The resulting passive spore dispersal is relatively rare amongst the Ascomycota. The mazaedium, usually black, either sits atop a long thin stalk, or rests on (or is sometimes immersed within) the surface of the lichen substrate. Many other Caliciaceae species generate spores in an apothecium, which typically resembles a flattened black disc.
The family contains species with crustose (crusty), foliose (leafy), and, in a few instances, fruticose (shrubby) growth forms. The photobiont partner of Caliciaceae lichens is usually from the green algal genus Trebouxia. Collectively, the family has a cosmopolitan distribution, and can be found on all major land masses. Although the family is best represented in mountainous areas of temperate and tropical regions, a few hardy species can survive the harsh environment offered by Antarctica's McMurdo Dry Valleys by growing in cracks on the surface of rocks. Five Caliciaceae species are included in the International Union for Conservation of Nature's Red List of Threatened Species. Some air pollution-resistant species in the genus Pyxine have been investigated for use as biomonitors of heavy metal pollution. Several fossils of Caliciaceae found as inclusions in amber have been used to evaluate the evolutionary history of the family.