Leptogium

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Leptogium
Leptogium phyllocarpum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Peltigerales
Family: Collemataceae
Genus: Leptogium
(Ach.) Gray (1821)
Type species
Leptogium lacerum
(Sw.) Gray (1821)

Leptogium is a genus of lichen-forming fungi in the family Collemataceae.[1] It has about 110 species.[2] Species formerly classified under Leptogium have since been divided among the genera Leptogium, Pseudoleptogium, and Scytinium. Leptogium lichens are predominantly found on tree bark or soil, often among mosses, and sometimes on rocks in moist environments.[3]

Taxonomy

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In 2013, a proposal supported by molecular phylogenetics data was made to conserve the genus Leptogium with a conserved type, aiming to maintain the current broader classification including both small-squamulose and larger foliose species within Leptogium, while segregating the smaller squamulose species into Scytinium.[4] This conservation was recommended by a vote of 14-0-1 to prevent the necessity of reclassifying about 100 species into new genera such as 'Mallotium. The proposal was widely supported by the Nomenclature Committee for Fungi as it simplifies the taxonomy and maintains historical continuity for the genus Leptogium.[5]

Description

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Leptogium is characterized by its foliose, gelatinous thallus, which varies in colour from blue-grey to olive-brown or blackish. The upper and lower cortex of these lichens consists of a single layer of roughly equal-sized cells. The medulla, on the other hand, is made up of loosely intertwined hyphae intermingled with chains of photobiont cells. The upper surface of the thallus can range from smooth to wrinkled or ridged, often exhibiting a glossy appearance, while the lower surface may be smooth, web-like, or hairy, sometimes featuring small clusters of white rhizines.[3]

Leptogium species often possess isidia and have Nostoc as their photobiont. The ascomata are apothecia, which can be sessile or shortly stalked and are predominantly laminal. The thalline margin may persist or become excluded, occasionally displaying a lobulate form. The true exciple is raised, cup-shaped, and mainly composed of periclinally arranged hyphae, with a colour that varies from colourless to reddish-brown. The disc of the lichen is either concave or flat.[3]

The epithecium is colourless to reddish-brown and does not react with solutions of either potassium hydroxide or ammonia. The hymenium is colourless and turns blue when exposed to iodine. The hypothecium is shallow and either colourless or pale yellowish. The hamathecium consists of numerous, conglutinate paraphyses with slightly swollen apices. The asci are club-shaped (clavate) and contain four to eight spores, with the wall and apical dome turning blue in response to potassium hydroxide and iodine. Ascospores are ellipsoidal, ovoid, or fusiform, sometimes featuring an apiculate end, and are septate and colourless. Lichen substances have not been detected by thin-layer chromatography in Leptogium species.[3]

Species

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As of April 2023, Species Fungorum (in the Catalogue of Life) accepts 84 species of Leptogium.[1]

Leptogium chloromelum
Leptogium cochleatum
Leptogium javanicum
Leptogium phyllocarpum
Leptogium saturninum

References

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  1. ^ a b "Leptogium". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 19 April 2023.
  2. ^ 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 [154]. doi:10.5943/mycosphere/13/1/2. hdl:10481/76378.
  3. ^ a b c d Cannon, Paul; Otálora, Mónica A.G.; Košuthová, Alica; Wedin, Mats; Aptroot, André; Coppins, Brian; Simkin, Janet (2020). "Peltigerales: Collemataceae, including the genera Blennothallia, Callome, Collema, Enchylium, Epiphloea, Lathagrium, Leptogium, Pseudoleptogium, Rostania and Scytinium". Revisions of British and Irish Lichens. 2: 1–38 [21–22]. doi:10.34885/174. Open access icon
  4. ^ Jørgensen, Per M.; Otalora, Monica; Wedin, Mats (2013). "(2235) Proposal to conserve the name Leptogium (lichenized Ascomycota) with a conserved type". Taxon. 62 (6): 1333–1334. doi:10.12705/626.23.
  5. ^ May, Tom C.; Lendemer, James C. (2023). "Report of the Nomenclature Committee for Fungi: 22". Taxon. 72 (6): 1356–1363. doi:10.1002/tax.13099.
  6. ^ a b Jørgensen, Per M.; Buck, William R. (2013). "Further contributions to the lichen genus Leptogium in southern South America". The Lichenologist. 45 (6): 787–789. doi:10.1017/s0024282913000443.
  7. ^ a b c Kitaura, M.J.; Scur, M.C.; Spielmann, A.A.; Lorenz-Lemke, A.P. (2018). "A revision of Leptogium (Collemataceae, lichenized Ascomycota) from Antarctica with a key to species". The Lichenologist. 50 (4): 467–485. doi:10.1017/S0024282918000269.
  8. ^ Jørgensen, P.M.; James, P.W. (1983). "Studies on some Leptogium species of western Europe". The Lichenologist. 15 (2): 109–125. doi:10.1017/s0024282983000183.
  9. ^ a b c d e Lindström, M. (2007). "New species in the lichen genus Leptogium (Collemataceae) from tropical South America". Bibliotheca Lichenologica. 95: 405–428.
  10. ^ a b c d e Verdon, D. (1990). "New Australasian species and records in the genus Leptogium S. Gray (lichenized Ascomycotina: Collemataceae)". Mycotaxon. 37: 413–440.
  11. ^ Marcelli, M.P.; Jungbluth, P.; Benatti, M.N.; Spielmann, A.A.; Canêz, L.S.; Cunha, I.P.R.; Martins, M.F.N. (2007). "Some new species and combinations of Brazilian lichenized fungi". In Frisch, Andreas; Lange, Ute; Staiger, Bettina (eds.). Lichenologische Nebenstunden. Contributions to lichen taxonomy and ecology in honour of Klaus Kalb. Bibliotheca Lichenologica. Vol. 96. pp. 209–228.
  12. ^ a b Kitaura, M.J.; Marcelli, M.P. (2013). "A revision of Leptogium species with spherical-celled hairs (Section Mallotium p.p.)". The Bryologist. 116: 15–27. doi:10.1639/0007-2745-116.1.015.
  13. ^ Kitaura, M.J.; Marcelli, M.P.; da Hora, B.R.; Jungbluth, P. (2015). "Leptogium denticulatum (Collemataceae, lichenized Ascomycota) and some morphologically related species". The Bryologist. 118 (1): 11–21. doi:10.1639/0007-2745-118.1.011.
  14. ^ a b c Dube, Archana; Makhija, Urmila (2010). "Occurrence of four additional non-hairy species of Leptogium from Maharashtra, India". The Lichenologist. 42 (6): 701–710. doi:10.1017/s0024282910000332.
  15. ^ Wilson, F.R.M. (1893). "The lichens of Victoria. Part 1". Proceedings of the Royal Society of Victoria. 5: 141–177 [157].
  16. ^ Jørgensen, Per M.; Olley, Louise (2010). "A new hairy Leptogium from Nepal". The Lichenologist. 42 (4): 387–389. doi:10.1017/s0024282909990764.
  17. ^ Kitaura, M.J.; Marcelli, M.P. (2012). "The Leptogium juressianum complex in southeastern Brazil". Mycotaxon. 120: 215–221. doi:10.5248/120.215.
  18. ^ a b Liu, H.J.; Xi, M.Q.; Hu, J.S.; Wu, Q.F. (2015). "Two new species and a new record of Leptogium from China". Mycotaxon. 130 (2): 471–478. doi:10.5248/130.471.
  19. ^ Liu, H.J.; Guan, S. (2012). "A new hairy species of Leptogium (Collemataceae) from China". Mycotaxon. 119: 413–417. doi:10.5248/119.413.
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