Crater lichen (Diploschistes ocellatus)

Description

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Crater lichen fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Crater lichen description

Diploschistes ocellatus is a widespread lichen species that grows on calcareous rocks and soils. Its numerous thalli are powdery pale grey to white, with each thick thallus enclosing a black apothecium (a disc-like structure on the surface of the thallus used in sexual reproduction) ⁽²⁾. 

There are two different morphs of Diploschistes ocellatus, which differ in the structure of the thallus and apothecia and in the presence or absence of tiny pores on the surface, known as pseudocyphellae ⁽³⁾.

Synonyms

Diploschistes subocellatus, Lagerheimina ocellata, Lichen ocellatus, Parmelia ocellata, Urceolaria ocellata, Urceolaria subocellata.

Crater lichen biology

Lichens are a unique group of organisms that consist of two components, a fungus (called the ‘mycobiont’) and an alga or cyanobacterium (called the ‘photobiont’) that live in a close symbiotic relationship ^{(4) (5) (6)}. The fungus produces the thallus (the main lichen body) which houses the alga or the cyanobacterium, providing protection and creating optimal conditions for the photobionts to photosynthesise. This process produces sugars and other nutrients which can then be used by the fungus ⁽⁶⁾.

Crater lichen range

A wide-ranging species, Diploschistes ocellatus occurs from southern Europe and Africa, across Asia to Australia, New Zealand and some islands in the western Pacific Ocean ⁽²⁾.

Crater lichen habitat

Diploschistes ocellatus grows on calcareous rocks and soils ⁽²⁾. One morph of this species grows only on soils in arid areas of southern Spain which contain the very soft mineral gypsum ⁽³⁾.

Crater lichen status

Diploschistes ocellatus has not yet been classified by the IUCN.

Crater lichen threats

Although it is not known if there are any specific threats to Diploschistes ocellatus, lichens are a slow-growing association of fungi and algae or cyanobacterium, and so are extremely sensitive to contamination from air pollution. As such, lichens are often used as indicators of the amount of pollution in an ecosystem ⁽⁵⁾.

Crater lichen conservation

Diploschistes ocellatus has not been the target of any known conservation measures.

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Glossary

Alga

A simple plant that lacks roots, stems and leaves but contains the green pigment chlorophyll. Most algae occur in marine and freshwater habitats.

Calcareous

Containing free calcium carbonate, chalky.

Cyanobacteria

A group of bacteria that contain the pigment chlorophyll and are able to photosynthesise. Once known as ‘blue-green algae’, cyanobacteria are thought to have been the first organisms to produce oxygen; fossil cyanobacteria have been found in 3000 million year old rocks. As they are responsible for the oxygen in the atmosphere they have played an essential role in influencing the course of evolution on this planet.

Fungus

Fungi are one of the taxonomic kingdoms, separate from plants and animals. They obtain nutrients by absorbing organic compounds from the surrounding environment.

Morph

One of two or more distinct types of a given species, often distinct colour forms, which occur in the same population at the same time (that is, are not geographical or seasonal variations).

Photosynthesis

Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.

Symbiotic

Describes a relationship in which two organisms form a close association. The term is now usually used only for associations that benefit both organisms (a mutualism).

Thallus

Type of simple plant body that does not have stems, leaves and roots.

References

1. Species 2000 and ITIS Catalogue of Life (August, 2009)
   http://www.catalogueoflife.org
2. Vasser, S.P. and Nevo, E. (2005) Lichen-forming, Lichenicolous, and Allied Fungi of Israel. A.R.G. Gantner Verlag K.G., Germany. 
3. Martín, M.P., Winka, K., Llimona, X. and. Lumbsch H.T. (2000) Evaluation of morphological variation in the lichen Diploschistes ocellatus (Ascomycota, Ostropales): evidence from nuclear rDNA ITS sequence data. Plant Biology, 2: 571-578.
4. Ghazanfar, S.A. and Fisher, M. (1998) Vegetation of the Arabian Peninsula. Kluwer Academic Publishers, Dordrecht, the Netherlands.
5. Nash, T.H. (1996) Lichen Biology. Cambridge University Press, Cambridge.
6. Ahmadjian, V. (1993) The Lichen Symbiosis. John Wiley & Sons, Inc., New York.