SafePlants

Shell Lichen

Considerations for Pets

• Shell Lichen sometimes grows on shells. Animals, like dogs, who might find shells, could ingest the lichen while chewing on or playing with shells containing lichen.

Common Names and Scientific Name

• Common Name: Shell Lichen
• Scientific Name: Primarily associated with the genus *Arthopyrenia*, but may also refer to other lichen species.

Taxonomy and Nomenclature

• Kingdom: Plantae (referring to lichens as plants in a general sense)
• Genus: *Arthopyrenia* A. Massal.
• Family: Monoblastiaceae (for Hollow Shell Lichen)
• Synonyms/Related Species:
  • *Arthopyrenia cinchonae* (Ach.) Mull. Arg. - Cinchona Shell Lichen
  • *Arthopyrenia cinereopruinosa* (Schraerer)

Distribution and Habitat

• Found in various locations, including Allegany Co., Maryland.
• Marine species like *Thelidium litorale* are found on shells in intertidal zones.
• Observed in the Scottish Highlands.

Morphological Characteristics and Growth Habits

• Shell Lichens are pioneers of life, often the first inhabitants of rocks, displaying a small, shell-like appearance.
• They can be replaced by leafy and bushy lichens over time.
• *Collemopsidium foveolatum* (lichen) is described as 0.10–0.24 mm in diameter, black, flattened to moderately convex, and immersed in pits in shells and softer rocks.

Interactions with Other Organisms

• Snails graze on lichen material and apply it to their shells, potentially creating prominent protuberances.
• The black lichen, *Verrucaria mucosa*, can often be seen growing on limpet shells.
• Coleoptera (beetles) may have lichen attached to their shell fragments.

Resources and Further Information

• Maryland Biodiversity website
• Wikimedia Commons (for images)
• Garden Guides website
• www.sararegistry.gc.ca
• Sighting Reports: 1-866-727-3447 or sightings@ speciesatrisk.ca