Biology:Placidium

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Short description: Genus of lichens

Placidium
Tree Stipplescale (4752735806).jpg
Placidium arboreum
Scientific classification e
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Eurotiomycetes
Order: Verrucariales
Family: Verrucariaceae
Genus: Placidium
A.Massal. (1855)
Type species
Placidium michelii
A.Massal. (1856)

Placidium is a genus of crustose to squamulose to almost foliose lichens. The genus is in the family Verrucariaceae.[1] Most members grow on soil (are terricolous), but some grow on rock (saxicolous).[2] The fruiting bodies are perithecia, flask-like structures immersed in the lichen body (thallus) with only the top opening visible, dotting the thallus. Lichen spot tests are all negative. Members of the genus lack rhizines, but otherwise resemble members of the genus Clavascidium.[2]

Members of the genus are commonly called stiplescale lichens or earthscale.[2]:327

Taxonomy

The genus was circumscribed in 1855 by Italian lichenologist Abramo Bartolommeo Massalongo.[3]

María Prieto and Ibai Olariaga suggest that Placidium is a superfluous illegitimate name according to strict application of nomenclatural rules. This is because when Massalongo circumscribed the genus in 1855, he included the original type species of genus Endocarpon, E. pusillum. When Othmar Breuss resurrected the genus for use in 1996,[4] he assigned P. michelii as its type, even though Massalongo did not include P. michelii in Placidium in his original 1855 circumscription, but rather in a later treatment of the genus. In 2019, Prieto and Olariaga submitted a proposal to conserve the name Placidium with Placidium michelii as its conserved type species.[5]

Species

  • Placidium arboreum (Schwein. ex E. Michener) Lendemer (2004)
  • Placidium californicum Breuss (2000)[6] – USA
  • Placidium lesdainii Breuss (2002)
  • Placidium nigrum T.T.Zhang & X.L.Wei (2022)[7] – China
  • Placidium nitidulum T.T.Zhang & X.L.Wei (2022)[7] – China
  • Placidium podolepis (Breuss) M.Prieto (2012)
  • Placidium umbrinum (Breuss) M.Prieto & Breuss (2009)
  • Placidium varium T.T.Zhang & X.L.Wei (2022)[7] – China
  • Placidium yoshimurae (H.Harada) Breuss (1996)

References

  1. Wijayawardene, N.N.; Hyde, K.D.; Dai, D.Q.; Sánchez-García, M.; Goto, B.T.; Saxena, R.K. et al. (2022). "Outline of Fungi and fungus-like taxa – 2021". Mycosphere 13 (1): 53–453. doi:10.5943/mycosphere/13/1/2. https://www.researchgate.net/publication/358798332. 
  2. 2.0 2.1 2.2 Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, ISBN:978-0-300-19500-2
  3. Massalongo, A. (1855) (in la). Symmicta lichenum novorum vel minus cognitorum. Verona: Typis Antonellianis. https://books.google.com/books?id=zU0-AAAAcAAJ&pg=PA75. 
  4. Breuss, O. (1996). "Ein verfeinertes Gliederungskonzept für Catapyrenium (lichenisierte Ascomyceten, Verrucariaceae)" (in de). Annalen des Naturhistorischen Museums Wien 98 (Suppl.): 35–50. 
  5. Prieto, María; Olariaga, Ibai (2019). "(2697–2698) Proposals to conserve the names Placidium and P. michelii with conserved types (Verrucariales: lichenized Ascomycota)". Taxon 68 (4): 855–856. doi:10.1002/tax.12100. 
  6. Breuss, O.; Bratt, C.C. (2000). "Catapyrenioid lichens in California". Bulletin of the California Lichen Society 7 (2): 36–42. 
  7. 7.0 7.1 7.2 Zhang, Tingting; Zhang, Xin; Yang, Qiuxia; Wei, Xinli (2022). "Hidden species diversity was explored in two genera of catapyrenioid lichens (Verrucariaceae, Ascomycota) from the deserts of China". Journal of Fungi 8 (7): e729. doi:10.3390/jof8070729. PMID 35887484. PMC 9319096. https://www.researchgate.net/publication/362316368. 

Wikidata ☰ Q7200385 entry