Wikipedia

Diploschistes

Diploschistes is a genus of lichen-forming fungi in the family Graphidaceae.[2] Commonly known as crater lichens, members of the genus are crustose lichens with a thick, cracked (areolate) body (thallus) with worldwide distribution.[3]: 264 [4][5] The fruiting part (apothecia) are immersed in the thick thallus so as to have the appearance of being small "craters".[3]: 264  The widespread genus contains about 43 species.[6]

Diploschistes
Diploschistes scruposus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Graphidales
Family: Graphidaceae
Genus: Diploschistes
Norman (1853)
Type species
Diploschistes scruposus
(Schreb.) Norman (1853)
Species

~43

Synonyms[1]

Taxonomy

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Johannes Musæus Norman originally circumscribed the genus in 1853.[7] It is in the family Graphidaceae. In 2018,[8] Kraichak and colleagues, using a "temporal phylogenetic" approach to identify temporal bands for specific taxonomic ranks, proposed placing Diploschistes as the type genus of Diploschistaceae, a family originally proposed by Alexander Zahlbruckner in 1905.[9] This taxonomic proposal was rejected by Robert Lücking in a critical 2019 review of the temporal method for the classification of lichen-forming fungi, using this specific example to highlight several drawbacks of this approach.[10]

Description

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The thallus (lichen body) of Diploschistes species can be continuous or cracked into small, areolate sections. It varies in colour from grey-white to dark grey or yellowish and can have a smooth to warty (verrucose) surface, often covered with a powdery coating (pruinose). The medulla, the inner layer of the thallus, reacts with iodine (I) to turn blue, although this reaction can be variable. The photobiont, or photosynthetic partner, in these lichens is Trebouxia, a type of green algae.[11]

The ascomata (fruiting bodies) start off resembling perithecia (flask-shaped structures) and later become urn-shaped (urceolate) and immersed in the thallus. The disc, or central part, is black and sometimes pruinose. A thalline margin (a rim of thallus tissue around the apothecia) is present and can either blend in with the thallus or be thick and pruinose. The true exciple, a ring of tissue around the apothecia, is fused with the thalline margin and is dark brown to black. It consists of thick-walled, swollen to more or less spherical (globose) cells embedded in a matrix, and extends into pale brown periphysoids at the upper inside margin. These structures are faintly septate and not swollen at the tip, often appearing as a fringe on the surface and may close the ascomatal opening under dry conditions.[11]

The epithecium, the uppermost layer of cells in the apothecia, can be colourless to black and sometimes contains crystalline inclusions. The hymenium, a spore-bearing layer, is colourless and does not react with iodine (I–). The hypothecium, the layer below the hymenium, can be colourless to dark brown or black. The hamathecium, comprising the paraphyses (sterile filaments among the asci), consists of wavy, mostly unbranched filaments that are sparsely septate and sometimes brown at the tips.[11]

 
Ascospores of Diploschistes diacapsis

The asci (spore-producing cells) are elongated and club-shaped to somewhat cylindrical, with walls that are evenly thickened at maturity. When young, they have a somewhat abrupt apical thickening with a thin internal apical beak or a downward convex swelling, but lack any apical apparatus. The contents of the asci react with potassium/iodine (K/I) to turn orange-red, while the walls do not react (K/I–). They are not fissitunicate (do not split open at maturity) and contain between one and eight spores. Ascospores are broadly ellipsoidal, brown to dark brown or purple-black when mature, and blue-green when immature. They are muriform (having multiple transverse and longitudinal septa), smooth, and lack a distinct outer layer (perispore). They may react with iodine to turn blue (I± blue).[11]

Conidiomata, which produce asexual spores, are in the form of pycnidia (flask-shaped structures) that appear as slightly raised black warts. The conidiogenous cells, which produce the conidia (asexual spores), are either unbranched or branched at the base and are elongated and flask-shaped. The conidia are bacilliform (rod-shaped) to elongated-ellipsoidal, truncate (flat) to pointed at the base, colourless, and do not have septa.[11]

Diploschistes lichens contain para-depsides, such as lecanoric and diploschistesic acids, which are secondary metabolites (lichen products) that can be identified through chemical tests.[11]

Species

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Diploschistes diacapsis
 
Diploschistes muscorum

References

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  1. ^ "Diploschistes Norman 1853". MycoBank. International Mycological Association. Retrieved 2011-09-20.
  2. ^ "Diploschistes". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 8 April 2023.
  3. ^ a b Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, ISBN 978-0-300-19500-2
  4. ^ USDA Natural Resources Conservation Service Name Search
  5. ^ Crater Lichen (Diploschistes), Encyclopedia of Life
  6. ^ Kirk PM, Cannon PF, Minter DW, Stalpers JA (2008). Dictionary of the Fungi (10th ed.). Wallingford, UK: CABI. p. 213. ISBN 978-0-85199-826-8.
  7. ^ Norman, J.M. (1852). "Conatus praemissus redactionis novae generum nonnullorum Lichenum in organis fructificationes vel sporis fundatae" [An attempt at a new arrangement of some genera of lichens based on their reproductive structures or spores]. Nytt Magazin for Naturvidenskapene [New Magazine for the Natural Sciences] (in Latin). 7: 213–252.
  8. ^ Kraichak, Ekaphan; Huang, Jen-Pan; Nelsen, Matthew; Leavitt, Steven D.; Lumbsch, H. Thorsten (2018). "A revised classification of orders and families in the two major subclasses of Lecanoromycetes (Ascomycota) based on a temporal approach". Botanical Journal of the Linnean Society. 188 (3): 233–249. doi:10.1093/botlinnean/boy060.
  9. ^ Engler, H.G.A.; Prantl, K.A.E. (1905). Die Natürlichen Pflanzenfamilien nebst ihren Gattungen und wichtigeren Arten [The Natural Plant Families along with their Genera and Important Species]. 1 (in German). pp. 97–144 [121].
  10. ^ Lücking, Robert (2019). "Stop the abuse of time! Strict temporal banding is not the future of rank-based classifications in Fungi (including lichens) and other organisms". Critical Reviews in Plant Sciences. 38 (3): 199–253. doi:10.1080/07352689.2019.1650517.
  11. ^ a b c d e f Aptroot, A.; Weerakoon, G.; Cannon, P.; Coppins, B.; Sanderson, N.; Simkin, J. (2023). Ostropales: Graphidaceae, including the genera Allographa, Clandestinotrema, Crutarndina, Diploschistes, Fissurina, Graphis, Leucodecton, Phaeographis, Schizotrema, Thelotrema and Topeliopsis (PDF). Revisions of British and Irish Lichens. Vol. 36. pp. 4–5. 
  12. ^ Pérez-Vargas, Israel; Hernández-Padrón, Consuelo; Paz, Pedro L. Pérez de; Elix, John A. (2012). "A new saxicolous species of Diploschistes (Thelotremataceae ) from the Canary Islands". The Lichenologist. 44 (1): 67–71. doi:10.1017/S0024282911000612.
  13. ^ Vainio, E.A. (1899). "Lichenes novi rarioresque" [New and rare lichens]. Beiblatt zur Hedwigia. II (in Latin). 38: 186–190.
  14. ^ Lumbsch, H.T.; Mangold, A. (2007). "Diploschistes elixii (Ostropales: Thelotremataceae), an overlooked terricolous species from Western Australia". The Lichenologist. 39 (5): 459–462. doi:10.1017/S0024282907007049.
  15. ^ Lumbsch, H.T.; Elix, J.A. (1989). "Taxonomy of some Diploschistes spp. (lichenized ascomycetes, Thelotremataceae) containing gyrophoric acid". Plant Systematics and Evolution. 167 (3–4): 195–199. doi:10.1007/BF00936406. JSTOR 23673948.
  16. ^ Lumbsch, H.T.; Elix, J.A. (1985). "A new species of the lichen genus Diploschistes from Australia". Plant Systematics and Evolution. 150 (3–4): 275–279. doi:10.1007/BF00984201.
  17. ^ Lumbsch, H.T.; Elix, J.A. (2003). "The lichen genus Diploschistes (Thelotremataceae) in Australia". Bibliotheca Lichenologica. 86: 119–128.
  18. ^ Ababaikeli, Gulibahaer; Abbas, Abdulla; Guo, Shou-Yu; Tumier, Aniwaer; Mamuti, Reyimu (2016). "Diploschistes tianshanensis sp. nov., a corticolous species from Northwestern China". Mycotaxon. 131 (3): 565–574. doi:10.5248/131.565.
  19. ^ Ababaikeli, G.; Abdulla, A.; Abbas, A.; Guo, S.Y.; Tumur, A. (2018). "Diploschistes wui sp. nov., an overlooked saxicolous lichen from Northwestern China". Mycotaxon. 133 (1): 141–148. doi:10.5248/133.141.
  20. ^ Abbas, A.; Guo, S.Y.; Ababaikeli, G.; Abdulla, A.; Xahidin, H. (2014). "Diploschistes xinjiangensis, a new saxicolous lichen from northwest China". Mycotaxon. 129 (2): 465–471. doi:10.5248/129.465.
 
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