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Phaeographis

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Phaeographis
Phaeographis dendritica in Portugal
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Graphidales
Family: Graphidaceae
Genus: Phaeographis
Müll.Arg. (1882)
Type species
Phaeographis dendritica
(Ach.) Müll.Arg. (1882)
Synonyms[1]
List
  • Lecanactis Eschw. (1824)
  • Pyrochroa Eschw. (1824)
  • Platygramma G.Mey. (1825)
  • Ustalia Fr. (1825)
  • Leiogramma Eschw. (1833)
  • Ectographis Trevis. (1853)
  • Chiographa Leight. (1854)
  • Hymenodecton Leight. (1854)
  • Pyrographa Fée ex A.Massal. (1860)
  • Theloschisma Trevis. (1860)
  • Gymnographa Müll.Arg. (1887)
  • Gymnographomyces Cif. & Tomas. (1953)
  • Phaeographidomyces Cif. & Tomas. (1953)

Phaeographis is a genus of lichen-forming fungi in the family Graphidaceae. It has an estimated 180 species.[2]

Taxonomy

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The genus Phaeographis was circumscribed by the Swiss lichenologist Johannes Müller Argoviensis in 1882.[3] However, its taxonomic status was uncertain for many years due to the existence of several earlier generic names that potentially had priority.

In 2007, Robert Lücking and colleagues proposed to conserve the name Phaeographis against six earlier names: Creographa, Ectographis, Flegographa, Hymenodecton, Platygramma, and Pyrographa.[3] They also proposed to conserve Phaeographis dendritica as the type species. This proposal was made to maintain nomenclatural stability, as Phaeographis had become a widely used name representing about 150 species.[3]

The proposal was based on a revised generic concept of Graphidaceae presented by the German lichenologist Bettina Staiger, which for the first time provided a detailed analysis of the taxonomic relationships between genera in the family, using both morphological and molecular data.[3]

In 2010, the Nomenclature Committee for Fungi reviewed the proposal and recommended its acceptance with a strong majority (85.7% in favour).[4] This recommendation effectively conserved the name Phaeographis with P. dendritica as its type species, securing its taxonomic status and preventing the need to transfer numerous species to other genera.[4] This conservation was particularly important because Phaeographis represents the second largest genus in the family Graphidaceae, containing approximately 150 species. The conservation of the name is expected to maintain stability in the taxonomy of this significant group of lichens.[3][4]

Description

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The genus Phaeographis consists of crustose lichens, characterised by their thin, often inconspicuous thallus, which adheres closely to the substrate. In European species, the hyphae within the thallus react to iodine staining (I+) by turning blue, indicating the presence of specific starch-like compounds. The photobiont, or photosynthetic partner, is a green alga of the genus Trentepohlia, which is common in many lichens.[5]

The reproductive structures of Phaeographis are apothecia, which are fruiting bodies that vary in form from unbranched to branched or star-like (stellate). These structures are lirellate, meaning they are elongated and slit-like in appearance. They are typically immersed within the thallus but may protrude slightly. The margin of the thallus surrounding the apothecia is generally inconspicuous, blending into the rest of the lichen surface. The true exciple, a layer of tissue surrounding the hymenium (the spore-producing region), is thin and black, and may or may not extend beneath the hymenium. The disc of the apothecia is expanded and ranges in colour from brown to black. It is often matt in texture and may be coated with a white powdery substance (pruina).[5]

The internal structure of the apothecia includes a colourless hymenium that does not react with iodine (I–) and contains crystalline inclusions. The hamathecium, the network of sterile filaments between the spore-producing asci, is composed of unbranched paraphyses. These filaments have clavate (club-shaped) apical cells that are brownish in colour. The asci are of the Graphis-type, containing eight spores each, and do not react with iodine (K/I–).[5]

Ascospores are initially colourless but soon develop a pale to reddish-brown colouration within the ascus. They are I+ (purple) and are transversely divided into many segments, forming lens-shaped cells. Aphaeographis also reproduces asexually through structures called pycnidia, which produce ellipsoidal conidia. These conidia are typically straight or slightly curved.[5]

Species

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Phaeographis inusta
Phaeographis lyellii
Phaeographis multicolor

References

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  1. ^ "Synonymy. Current Name: Phaeographis Müll. Arg., Flora, Regensburg 65(21): 336 (1882)". Species Fungorum. Retrieved 8 September 2024.
  2. ^ Wijayawardene, Nalin; Hyde, Kevin; Al-Ani, LKT; S, Dolatabadi; Stadler, Marc; Haelewaters, Danny; et al. (2020). "Outline of Fungi and fungus-like taxa". Mycosphere. 11: 1060–1456. doi:10.5943/mycosphere/11/1/8. hdl:10481/61998.
  3. ^ a b c d e Lücking, Robert; Kalb, Klaus; Staiger, Bettina; McNeill, John (2007). "(1792) Proposal to conserve the name Phaeographis, with a conserved type, against Creographa, Ectographis, Flegographa, Hymenodecton, Platygramma, and Pyrographa (Ascomycota: Ostropales: Graphidaceae), along with notes on the names Graphina and Phaeographina". Taxon. 56 (4): 1296–1299. doi:10.2307/25065924. JSTOR 25065924.
  4. ^ a b c Norvell, Lorelei L. (2010). "Report of the Nomenclature Committee for Fungi: 15". Taxon. 59 (1): 291–293. doi:10.1002/tax.591029.
  5. ^ a b c d 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. p. 14.Open access icon
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