Cephalodium

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Apple lichen ( Peltigera aphthosa ) with blue-black external cephalodes

Cephalodium (plural: cephalodia ) is a term from lichen science ( lichenology ).

Cephalodies are demarcated areas in lichens that contain cyanobacteria (blue-green algae) as secondary symbionts in addition to fungus and green algae partners . These areas can either be inside the thallus (internal cephalodies) or sit on the bed (external cephalodes; the blue-green algae are separated from the outside by a layer of bark). Examples of external cephalodies can be found, for example, in some representatives of the Stereocaulaceae or Peltigeraceae . For example, they can be seen in the apple lichen ( Peltigera aphthosa ) as blue-black outgrowths. Internal cephalodies have, for example, Nephroma arcticum or Solorina crocea . The blue-green algae partners from the genera Nostoc , Stigonema or Scytonema come.

The advantage of this triple symbiosis is that the lichen ammonium is available as a nitrogen source directly from the atmospheric nitrogen , which the blue-green algae partner can fix using the enzyme nitrogenase . Nevertheless, cephalodies are comparatively rare and only occur in 3–4% of all lichen species.

Individual evidence

  1. ↑ Filip Högnabba, Soili Stenroos, Arne Thell: Evolution of cyanobacterial symbioses in Ascomycota . Biodiversity and Ecology of Lichens. Liber Amicorum Harrie Sipman. Bibliotheca Lichenologica Vol. 99, 2009, pp. 163-184.

literature

  • Georg Masuch: Biology of Lichen , Quelle & Meyer, Heidelberg / Wiesbaden (UTB f. Science), 1993, p. 53/54, ISBN 3-8252-1546-6 .
  • Herder-Lexicon of Biology, Spectrum Academ. Verlag, 1994, Vol. 2, p. 205, ISBN 3-86025-156-2 .