Biology:Diplotomma

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Diplotomma is a genus of lichen-forming fungi in the family Caliciaceae.[1] The genus has a widespread distribution and contains 14 species. These lichens form firmly attached, crust-like patches that range from pale to dark grey and can appear smooth or cracked into an irregular mosaic pattern on their substrate. They produce black, disc-shaped fruiting bodies that start buried in the crust and later emerge to sit roughly flush with the surface, often dusted with a greyish-white powder.

Taxonomy

The genus was circumscribed by Julius von Flotow in 1849.[2] It was later wrapped into Buellia before being segregated from that genus by David Hawksworth in 1980.[3]

Description

Diplotomma species form a firmly attached, crust-like thallus that sits on the substrate as a clearly delimited patch; in a few lichen-inhabiting (lichenicolous) taxa the thallus may be very thin or partly immersed in the host. The surface ranges from pale to dark grey and can appear smooth or cracked into an irregular mosaic. A dense outer [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] is packed with minute crystals that remain intact when a fragment is placed in potassium hydroxide solution (the K test). The algal partner ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) is a single-celled green alga of the [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] type, which provides photosynthetic energy.[4]

The sexual fruit-bodies (apothecia) start out buried in the thallus and later emerge so that the black [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] sits roughly flush with the surface; a narrow, pale, scalloped rim of thallus tissue may encircle the disc in some species. The disc itself is often dusted with a greyish-white powder ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]). Microscopic examination shows only a rudimentary [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]], merging seamlessly with the underlying [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]], both of which are brown to nearly black. Thread-like paraphyses stand in the clear (I+ blue) hymenium; their tips swell and darken, giving the layer a tufted look. Each sac-like ascus contains eight ascospores that are divided by cross-walls into two or more cells (sometimes almost forming a brick pattern, [[Glossary of lichen terms#{{biology:{1}}}|submuriform]]) and have thick internal partitions ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]); mature spores are mid- to dark brown with rounded internal chambers ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]). Vegetative reproduction occurs in sunken, flask-shaped pycnidia that appear as tiny brown dots; these release colourless, oval conidia capable of starting new thalli. Chemically the genus is characterised by aromatic depsides, compounds that help separate its species from superficially similar grey crustose lichens.[4]

Selected species

As of June 2025, Species Fungorum (in the Catalogue of Life) accepts 14 species of Diplotomma:

  • Diplotomma alboatrum (Hoffm.) Flot. (1849)
  • Diplotomma cedricola (Werner) Etayo (2010)
  • Diplotomma chlorophaeum Szatala (1956)
  • Diplotomma epipolium (Ach.) Arnold (1869)
  • Diplotomma glaucoatrum (Nyl.) Cl.Roux (2015)[5]
  • Diplotomma hedinii (H.Magn.) P.Clerc & Cl.Roux (2004)[6]
  • Diplotomma murorum (A.Massal.) Coppins (1980)
  • Diplotomma niveum (Anzi) Szatala (1956)
  • Diplotomma parasiticum (B.de Lesd.) Diederich, Cl.Roux & Haluwyn (2014)
  • Diplotomma pharcidium (Ach.) M.Choisy (1950)
  • Diplotomma porphyricum Arnold (1872)
  • Diplotomma rivas-martinezii (Barreno & A.Crespo) Barreno & A.Crespo (2000)[7]
  • Diplotomma venustum (Körb.) Körb. (1860)
  • Diplotomma vezdanum (P.Scholz & Knoph) Coppins (2002)

References

  1. ↑ "Diplotomma". Species 2000: Leiden, the Netherlands. https://www.catalogueoflife.org/data/taxon/CCXF8. 
  2. ↑ Flotow, J.V. (1849). "Lichenes florae silesiae" (in German). Jahresbericht der Schlesischen Gesellschaft für vaterländische Kultur 27: 98–143. 
  3. ↑ Hawksworth, D.L.; James, P.W.; Coppins, B.J. (1980). "Checklist of British lichen-forming, lichenicolous and allied fungi". The Lichenologist 12 (1): 1–115. doi:10.1017/S0024282980000035. Bibcode: 1980ThLic..12....1H. 
  4. ↑ 4.0 4.1 Cannon, Paul; Prieto, Maria; Coppins, Brian; Sanderson, Neil; Scheidegger, Christoph; Simkin, Janet (2021). "Caliciales: Caliciaceae, including the genera Acolium, Amandinea, Buellia, Calicium, Diploicia, Diplotomma, Endohyalina, Monerolechia, Orcularia, Pseudothelomma, Rinodina and Tetramelas". Revisions of British and Irish Lichens 15: 1–35 [24]. doi:10.34885/174.  open access
  5. ↑ Roux, C. (2015). "Validigo de du kombinaĵoj publikigitaj far ROUX inter 2005 kaj 2014 — Validation de deux combinaisons publiées par Roux entre 2005 et 2014" (in eo). Bulletin de la Société Linnéenne de Provence 66: 91–92. 
  6. ↑ Clerc, P. (2004). "Les champignons lichénisés de Suisse – Catalogue bibliographique complété par des données sur la distribution et l'écologie des espèces" (in fr). Cryptogamica Helvetica 19: 292. 
  7. ↑ Molina, M. del C.; Crespo, A. (2000). "Comparison of development of axenic cultures of five species of lichen-forming fungi". Mycological Research 104 (5): 595–602. doi:10.1017/S0953756299002014. 
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Wikidata ☰ Q5280002 entry



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