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Lendemeriella exsecuta
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Teloschistales
Family:	Teloschistaceae
Genus:	Lendemeriella
Species:	L. exsecuta
Binomial name
Lendemeriella exsecuta (Nyl.) S.Y.Kondr. (2020)
Synonyms
Lecanora exsecuta Nyl. (1880) Callopisma exsecutum (Nyl.) Arnold (1886) Caloplaca exsecuta (Nyl.) Dalla Torre & Sarnth. (1902) Caloplaca nigricans var. exsecuta (Nyl.) H.Olivier (1909) Lecidea exsecuta (Nyl.) Hue (1913) Blastenia exsecuta (Nyl.) Servít (1929)

Lendemeriella exsecuta is a species of saxicolous (rock-dwelling) crustose lichen in the family Teloschistaceae.

Taxonomy

The species was first described in 1880 by the Finnish lichenologist William Nylander, who classified it as a member of the genus Lecanora. After having been shuffled to various genera in its taxonomic history, Sergey Kondratyuk transferred it to the genus Lendemeriella in 2020.

Description

Lendemeriella exsecuta is a crustose lichen, meaning it grows as a thin, crust-like layer tightly attached to its substrate. The main body (thallus) appears grey, occasionally dark grey or off-white, and forms a continuous surface that may develop small cracks creating distinct segments called areoles. These areoles measure 0.5–1 mm across and may appear slightly pinched at their base.

The reproductive structures (apothecia) are small disc-like organs measuring 0.2–0.7 mm in diameter. These sit directly on the surface without a stalk and display considerable colour variation – from brownish-yellow to orange-brown, eventually becoming completely black. The discs are surrounded by a raised rim (proper margin) that ranges from black to olive in colour and may eventually become less prominent as the disc becomes more convex.

When viewed under a microscope, the internal structure reveals several distinct layers. The spore-producing layer (hymenium) is colourless and 65–90 micrometres (μm) tall, occasionally reaching 135 μm. It contains cylindrical spore sacs (asci), each producing eight two-celled spores. These transparent spores are ellipsoid in shape, measuring roughly 12–16.5 by 6–7.5 μm, with a distinctive thickened area at their centre.

The lichen contains various chemical compounds, including several pigments that give it its characteristic appearance. When tested with common chemical spot tests, the thallus is K−, C−, and P−. However, the apothecia are K± (red). The lichen's chemistry includes several secondary metabolites such as parietin, emodin, and fragilin, along with a unique substance that remains unidentified. Like most lichens, it contains photosynthetic green algal cells (chlorococcoid photobiont) that provide energy through photosynthesis.

Habitat and distribution

Lendemeriella exsecuta primarily inhabits Arctic and alpine environments, where it grows on silica-rich rocks that have a basic (non-acidic) chemistry. This lichen shows a preference for sheltered locations protected from strong winds, particularly in areas around and above the treeline where conditions are humid. While it is believed to have a circumpolar distribution – occurring in a band around the Earth's polar regions – it is particularly well-documented in the Alps mountain range of Europe. In the Antarctic, it has been documented from the South Shetland Islands and the Antarctic Peninsula, where it often grows alongside Umbilicaria decussata and Usnea sphacelata. Placopsis antarctica is anther typical associate.

References

1. ^ "GSD Species Synonymy. Current Name: Lendemeriella exsecuta (Nyl.) S.Y. Kondr., in Kondratyuk, Lőkös, Farkas, Kärnefelt, Thell, Yamamoto & Hur, Acta bot. hung. 62(1-2): 121 (2020)". Species Fungorum. Retrieved 14 January 2025.
2. "Lendemeriella exsecuta (Nyl.) S.Y. Kondr". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 14 January 2025.
3. Nylander, W. (1880). "Addenda nova ad Lichenographiam europaeam. Contin. XXXIV" [New Additions to European Lichenography. Continuation XXXIV]. Flora (Regensburg) (in Latin). 63: 387–394.
4. Kondratyuk, S.Y.; Lőkös, L.; Farkas, E.; Kärnefelt, I.; Thell, A.; Yamamoto, Y.; Hur, J.-S. (2020). "Three new genera of the Teloschistaceae proved by three gene phylogeny" (PDF). Acta Botanica Hungarica. 62 (1–2): 109–136. doi:10.1556/034.62.2020.1-2.7.
5. ^ Nimis, P.L.; Conti, M.; Martellos, S. "Lendemeriella exsecuta (Nyl.) S. Y. Kondr". ITALIC 8.0, The Information System On Italian Lichens. Retrieved 14 January 2025.
6. Øvstedal, D.O.; Lewis Smith, R.I. (2001). Lichens of Antarctica and South Georgia. A Guide to Their Identification and Ecology. Cambridge, UK: Cambridge University Press. p. 138. ISBN 978-0-521-66241-3.
7. Galloway, David J.; Lewis-Smith, Ronald I.; Quilhot, Wanda (2005). "A new species of Placopsis (Agyriaceae: Ascomycota) from Antarctica". The Lichenologist. 37 (4): 321–327. doi:10.1017/s0024282905015094.

• Teloschistales
• Lichen species
• Lichens described in 1880
• Lichens of Antarctica
• Lichens of Europe
• Lichens of Subarctic America
• Taxa named by William Nylander (botanist)