Melanelia hepatizon
| Melanelia hepatizon | |
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Parmeliaceae |
| Genus: | Melanelia |
| Species: | M. hepatizon
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| Binomial name | |
| Melanelia hepatizon (Ach.) A.Thell (1995)
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| Synonyms[1] | |
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List
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Melanelia hepatizon, commonly known as the rimmed camouflage lichen or the rimmed brown-shield, is a species of saxicolous (rock-dwelling), foliose lichen in the family Parmeliaceae.[2] Its thallus, ranging in colour from brown to black, features narrow, elongated lobes that can be flat, convex, or concave. This lichen has a circumpolar distribution, occurring in Asia, Europe, North America, Iceland, and Greenland.
Taxonomy
[edit]The Swedish lichenologist Erik Acharius first scientifically described Melanelia hepatizon in 1799, initially classifying it in the eponymous genus Lichen, following the conventions established by Carl Linnaeus in Species Plantarum.[3] Over time, the species was reclassified into several different genera before being placed in Melanelia by Arne Thell in 1995.[4]
Chemical profiling and DNA barcoding have proven useful for the identification and discrimination of Melanelia species. These methods can effectively separate M. hepatizon from other closely related species.[5] Studies employing DNA barcoding have revealed considerable intraspecific genetic variability within Melanelia hepatizon. The high genetic distances observed among individual specimens of this species suggest the presence of previously unrecognised lineages. This indicates that what is currently classified as M. hepatizon may, in fact, encompass multiple distinct species that have not yet been identified due to their morphological similarity.[6] Molecular phylogenetics analysis shows that M. hepatizon has a sister relationship with M. stygia, the type species of the genus.[7]
In North America, the species has been called the "rimmed camouflage lichen" or the "rimmed brown-shield".[8][9]
Description
[edit]
Melanelia hepatizon has a dark brown, often shiny thallus.[8] It is usually closely attached (appressed) to its substrate. The thallus measures up to 3 cm in diameter,[9] and features narrow lobes, usually between 0.4 and 1.5 mm in width, occasionally reaching up to 2.5 mm. The edges of the lobes are distinctly thickened. This species lacks both soredia and isidia. A distinguishing characteristic of Melanelia hepatizon is the presence of conspicuous white pseudocyphellae (pores for gas exchange) along the lobe margins, especially around the margins of the apothecia (fruiting bodies).[8]
The lower surface of Melanelia hepatizon is black at the centre, transitioning to dark brown towards the edges. Rhizines are sparse and primarily located at the margins. The pycnidia (asexual fruiting bodies) are black, cylindrical structures that are usually conspicuous on or near the lobe margins. Apothecia are common in this species. They are lecanorine in form, with a red-brown to brown disc that can reach up to 5 mm in diameter. The conidia are dumbbell-shaped and measure between 4 and 6 μm in length.[8]
Chemistry
[edit]The medulla of Melanelia hepatizon reacts positively to the PD spot test, turning orange, and to the K test, turning deep yellow. It does not react to the KC or C tests.[8] The major secondary metabolites (lichen products identified in M. hepatizon include cryptostictic acid, stictic acid, and norstictic acid.[5]
Melanelia hepatizon contains various additional secondary fungal metabolites, commonly known as mycotoxins. These mycotoxins were identified using enzyme-linked immunosorbent assay (ELISA), a method known for its high selectivity, sensitivity, and accuracy. The major mycotoxins detected in Melanelia hepatizon include sterigmatocystin, alternariol, emodin, mycophenolic acid, citrinin, diacetoxyscirpenol, cyclopiazonic acid, and zearalenone. These metabolites contribute to the diverse biochemical profile of Melanelia hepatizon and are characteristic of the broader group of fungi-associated lichen substances.[10]
Habitat and distribution
[edit]A circumpolar species, Melanelia hepatizon has a wide ecological amplitude, growing in diverse environments ranging from arctic sea-level stands to alpine belts in meridional zones, and from oceanic to continental sites. In the Himalayas, it has been recorded at elevations of 3,600 m (11,800 ft) and 4,500 m (14,800 ft). The lichen colonises siliceous rocks, occasionally wood and mosses, in various lowland and mountain tundra communities, as well as in open, exposed alpine vegetation.[11] Its range includes China,[12] Iceland,[5] and Greenland.[6] It is widespread in Europe, having been reported from 23 countries there,[13][14] and is also widely distributed in the Russian Arctic.[15] Its range in North America includes the Pacific Northwest and the Rocky Mountains extending north to Alaska and other arctic regions in the west, and the Appalachians and Great Lakes regions in the east.[9]
Melanelia hepatizon is typically found in sun-exposed habitats in boreal, alpine, and Arctic zones. It is predicted to respond negatively to climate change due to its preference for cooler, stable environments. As temperatures rise and habitats shift, this species may face a decline in abundance and distribution.[6]
References
[edit]- ^ "GSD Species Synonymy. Current Name: Melanelia hepatizon (Ach.) A. Thell, Nova Hedwigia 60(3-4): 419 (1995)". Species Fungorum. Retrieved 13 June 2024.
- ^ "Melanelia hepatizon (Ach.) A. Thell". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 13 June 2024.
- ^ Acharius, E. (1798). Lichenographiae Svecicae Prodromus (in Latin). Linköping: D.G. Björn. p. 110.
- ^ Thell, A. (1995). "A new position of the Cetraria commixta group in Melanelia (Ascomycotina, Parmeliaceae)". Nova Hedwigia. 60 (3–4): 407–422.
- ^ a b c Xu, Maonian; Heidmarsson, Starri; Thorsteinsdottir, Margret; Eiriksson, Finnur F.; Omarsdottir, Sesselja; Olafsdottir, Elin S. (2017). "DNA barcoding and LC-MS metabolite profiling of the lichen-forming genus Melanelia: Specimen identification and discrimination focusing on Icelandic taxa". PLOS ONE. 12 (5): e0178012. Bibcode:2017PLoSO..1278012X. doi:10.1371/journal.pone.0178012. PMC 5443556. PMID 28542495.
- ^ a b c Leavitt, Steven D.; Esslinger, Theodore L.; Hansen, Eric Steen; Divakar, Pradeep K.; Crespo, Ana; Loomis, Bradley F.; Lumbsch, H. Thorsten (2014). "DNA barcoding of brown Parmeliae (Parmeliaceae) species: a molecular approach for accurate specimen identification, emphasizing species in Greenland". Organisms Diversity & Evolution. 14 (1): 11–20. doi:10.1007/s13127-013-0147-1.
- ^ Divakar, Pradeep K.; Del-Prado, Ruth; Lumbsch, H. Thorsten; Wedin, Mats; Esslinger, Theodore L.; Leavitt, Steven D.; Crespo, Ana (2012). "Diversification of the newly recognized lichen-forming fungal lineage Montanelia (Parmeliaceae, Ascomycota) and its relation to key geological and climatic events". American Journal of Botany. 99 (12): 2014–2026. doi:10.3732/ajb.1200258. PMID 23204485.
- ^ a b c d e Brodo, Irwin M.; Sharnoff, Sylvia Duran; Sharnoff, Stephen (2001). Lichens of North America. Yale University Press. p. 435. ISBN 978-0-300-08249-4.
- ^ a b c McMullin, R. Troy (2023). Lichens. The Macrolichens of Ontario and the Great Lakes Region of the United States. Firefly Books. p. 280. ISBN 978-0-228-10369-1.
- ^ Burkin, A.A.; Kononenko, G.P. (2014). "Secondary fungal metabolites (mycotoxins) in lichens of different taxonomic groups". Biology Bulletin of the Russian Academy of Sciences. 41 (3): 216–222. Bibcode:2014BioBu..41..216B. doi:10.1134/S1062359014030030.
- ^ Otte, Volker; Esslinger, Theodore L.; Litterski, Birgit (2005). "Global distribution of the European species of the lichen genus Melanelia Essl". Journal of Biogeography. 32 (7): 1221–1241. Bibcode:2005JBiog..32.1221O. doi:10.1111/j.1365-2699.2005.01268.x.
- ^ Wang, Hai-Ying; Chen, Jian-Bin; Wei, Jiang-Chun (2009). "A phylogenetic analysis of Melanelia tominii and four new records of brown parmelioid lichens from China". Mycotaxon. 107 (1): 163–173. doi:10.5248/107.163.
- ^ Hawksworth, David L.; Blanco, Oscar; Divakar, Pradeep K.; Ahti, Teuvo; Crespo, Ana (2008). "A first checklist of parmelioid and similar lichens in Europe and some adjacent territories, adopting revised generic circumscriptions and with indications of species distributions". The Lichenologist. 40 (1): 1–21. doi:10.1017/S0024282908007329.
- ^ Hawksworth, David L.; Divakar, Pradeep K.; Crespo, Ana; Ahti, Teuvo (2011). "The checklist of parmelioid and similar lichens in Europe and some adjacent territories: Additions and corrections". The Lichenologist. 43 (6): 639–645. doi:10.1017/S0024282911000454.
- ^ Andreev, Mikhail; Kotlov, Yuri; Makarova, Irina (1996). "Checklist of Lichens and Lichenicolous Fungi of the Russian Arctic". The Bryologist. 99 (2): 137–169 [148]. doi:10.2307/3244545. JSTOR 3244545.