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Cliostomum: A Genus of Lichen-Forming Fungi

Cliostomum is a genus of lichen-forming fungi belonging to the family Ramalinaceae. These lichens are characterized by their crustose thallus and association with algal partners. The following provides a detailed overview of this fascinating genus.

Taxonomy and Nomenclature

• Genus: Cliostomum Fr.
• Family: Ramalinaceae
• Order: Lecanorales
• Class: Lecanoromycetes
• Phylum: Lichens
• Kingdom: Not explicitly stated, but implicitly Fungi

Some recognized species within this genus include:

• Cliostomum flavidulum Hafellner &amp Kalb
• Cliostomum corrugatum (Ach. ex Fr.) Fr.
• Cliostomum griffithii (Sm.) Coppins - Griffith's Cliostomum Lichen
• Cliostomum leprosum (Rsnen) Holien
• Cliostomum luteolum
• Cliostomum pallens (Ekman 1997)
• Cliostomum tenerum (Nyl.)
• Cliostomum vitellinum
• Cliostomum acetabuli Diederich

Synonyms:

• Lecanora navarrensis (synonym of Cliostomum flavidulum)
• Catillaria griffithii (Sm.) Malme (synonym of Cliostomum griffithii)
• Catillaria tricolor auct. (synonym of Cliostomum griffithii)

Note: Several entries indicate that Lichen griffithii Sm. is an older classification for Cliostomum griffithii.

Distribution and Habitat

• Cliostomum luteolum and C. vitellinum are rare species found on trees with acidic bark in the oceanic northeastern United States and southeastern regions.
• Cliostomum corrugatum is largely confined to old oak stands. It is also found in heathland, in bare patches including those created after burning and on old untreated timber, especially in coastal areas.
• Cliostomum griffithii has been observed growing on ridges of tree trunk bark on sheltered sides of adjacent ash and sycamore trees and is found in Britain and Ireland, as well as Norway.
• Cliostomum flavidulum has been found in China, Yunnan.
• Species of Cliostomum have been documented in Belarus and the Aegean.

Morphological Characteristics

• Cliostomum species have a crustose thallus that can be thin to thick, continuous, and rimose (cracked) or without cracks.
• The surface of the thallus can be pale gray, pale yellow, pale green, or bluish gray, and may be smooth, wrinkled, or warted.
• Cliostomum corrugatum exhibits maritime trends and a thicker thallus.
• Cliostomum griffithii is a white crustose lichen.

Ecological Role

• Cliostomum lichens, particularly Cliostomum corrugatum, are epiphytic lichens. Studies have estimated their dispersal capacity and examined changes in their distribution.
• The presence of old trees is crucial for the survival of several Cliostomum species.

Interactions with Other Organisms

• Cliostomum griffithii serves as a food source for certain organisms, such as Trichadenotecnum sexpunctatum (L.), which feeds on the alga associated with the lichen (likely Apatococcus lobatus).
• Some Cliostomum species can be lichenicolous, meaning they are hosts to parasitic fungi.

Further Information

• British Lichen Society (BLS) Mapping Scheme dataset
• Herzogia 19