Thelenella

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Thelenella
T muscorum1.jpg
Thelenella muscorum
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Thelenellales
Family: Thelenellaceae
Genus: Thelenella
Nyl. (1855)
Type species
Thelenella modesta
(Nyl.) Nyl. (1855)
Species

See text

Synonyms [1]
List

Thelenella is a genus of lichen-forming fungi in the family Thelenellaceae. [2] [3] These inconspicuous lichens form thin, crust-like growths that are tightly attached to their substrates and appear as dull whitish, pale grey, or light brown patches. Species of Thelenella are commonly found in damp, shaded environments where they grow on tree bark, living leaves, moss cushions, rock faces, and moss-rich soil. The genus is distinguished by its thick-walled fruiting bodies that are mostly embedded within the lichen crust and contain multicellular spores with multiple cross-walls.

Contents

Taxonomy

The genus was circumscribed by the Finnish lichenologist William Nylander in 1855, with Thelenella modesta assigned as the type species. In his original description, Nylander characterised Thelenella by its pore-like fruiting bodies with an immersed perithecium that was either uncoloured or only superficially pale. He noted that the spores were somewhat large, oblong, and multicellular, whilst the gelatinous hymenium remained entirely colourless. Nylander distinguished the genus as morphologically distinct, noting that the fruiting bodies were quite different from those of Verrucaria . [4]

Description

Thelenella forms an inconspicuous, crust‑like thallus that lies tightly attached to its substrate and ranges from thin, membranous patches to cracked or warted crusts in dull whitish, pale grey, or light brown tones. The photosynthetic partner is a minute, spherical green alga of the trebouxioid type, evenly distributed through the fungal tissue. [5]

Sexual reproduction takes place in thick‑walled perithecia that are mostly immersed in the thallus. Their outer wall ( exciple ) is built of long, narrow cells arranged either lengthwise or in a tangled mesh; the pigment is evenly spread through this wall or diffused in a surrounding gel, never appearing grainy under high magnification. A second, darker protective layer ( involucrellum ) is rarely developed. Inside, the hymenial gel shows no reaction to iodine (I–, K/I–). Delicate, thread‑like paraphysoids branch and fuse, especially near their bases and tips, but they may be absent around the apical pore. The asci are fissitunicate , meaning they have two functional wall layers: a thin inner and a thicker outer one; they usually carry no iodine‑positive structures and contain two to eight ascospores. The spores themselves are colourless to slightly brown, with multiple cross‑walls that give them a somewhat muriform to strongly muriform appearance; their outer wall is only marginally thicker than the septa. [5]

Asexual propagation is achieved by Roccella ‑type pycnidia embedded in the thallus, which release colourless, rod‑shaped conidia lacking internal septa. No secondary metabolites (lichen products) have been detected in Thelenella species by thin-layer chromatography. [5]

Ecology

Species of Thelenella occupy a wide range of damp, shaded substrates. They most often grow directly on tree bark (corticolous) but can also colonise living leaves (foliicolous), bryophyte cushions on foliage (bryophilous), shaded rock faces (saxicolous), and patches of moss-rich soil (terricolous). [5]

Species

As of July 2025, Species Fungorum (in the Catalogue of Life) accepts 22 species of Thelenella. [3]

Thelenella melanospora Thelenella melanospora1.jpg
Thelenella melanospora
Thelenella modesta Thelenella modesta2.jpg
Thelenella modesta

References

  1. ↑ "Synonyms: Thelenella Nyl., Mém. Soc. Imp. Sci. Nat. Cherbourg 3: 193 (1855)". Species Fungorum . Retrieved 15 April 2022.
  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. doi: 10.5943/mycosphere/13/1/2 . hdl: 10481/76378 .
  3. 1 2 "Thelenella". Catalogue of Life . Species 2000: Leiden, the Netherlands. Retrieved 15 July 2025.
  4. ↑ Nylander, W. (1855). "Essai d'une nouvelle classification des lichens (second mémoire)". Mémoires de la Société Impériale des Sciences Naturelles de Cherbourg (in French). 3: 161–202 [193].
  5. 1 2 3 4 Orange, A.; Cannon, P. (2021). Ostropales: Thelenellaceae, including the genus Thelenella (PDF). Revisions of British and Irish Lichens. Vol. 8. pp. 1–4. Open Access logo PLoS transparent.svg
  6. ↑ Vainio, E.A. (1896). "Lichenes Antillarum a W.R. Elliott collecti". The Journal of Botany, British and Foreign (in Latin). 34: 292–297.
  7. 1 2 Morse, C.A. (2016). "Two new species of Thelenella and new reports from the Great Plains of central North America, with a world-wide key to the genus". Opuscula Philolichenum. 15: 22–36. doi:10.5962/p.386097.
  8. 1 2 3 4 5 6 7 Harris, Richard C. (1995). More Florida Lichens, Including the 10-cent Tour of the Pyrenolichens (PDF). Bronx, New York: New York Botanical Garden.
  9. 1 2 3 4 5 6 Mayrhofer, H. (1987). "Monographie der Flechtengattung Thelenella" [Monograph of the lichen genus Thelenella]. Bibliotheca Lichenologica. 26: 1–106.
  10. ↑ Halda, J.P.; Hur, J.S. (2016). "Thelenella haradae sp. nov., a saxicolous lichen from South Korea". Mycotaxon. 131 (4): 805–809. doi: 10.5248/131.805 .
  11. ↑ Pinokiyo; Singh; K.P.; A. (2006). "New species and new record of foliicolous lichenized fungi from Sikkim (India)". Mycotaxon. 97: 57–61.
  12. ↑ Aptroot, Andre; Andrade, Dannyelly Santos; Mendonça, Cléverton; Lima, Edvaneide Leandro de; Cáceres, Marcela Eugenia da Silva (2015). "Ten new species of corticolous pyrenocarpous lichens from NE Brazil". Phytotaxa. 197 (3): 197–206. Bibcode:2015Phytx.197..197A. doi:10.11646/phytotaxa.197.3.3.
  13. 1 2 Mayrhofer, H.; McCarthy, P.M. (1991). "Notes on the lichenized ascomycete genus Thelenella Nyl. in Australia, southern Africa and on the islands of the Subantarctic and Antarctic". Muelleria. 7 (3): 333–341. doi: 10.5962/p.198515 .
  14. ↑ Etayo, J.; Mayrhofer, H. (2003). "Thelenella melanospora (Thelenellaceae, lichenized Ascomycetes), a new species from the Mediterranean region". Nova Hedwigia. 77 (1–2): 109–114. Bibcode:2003NovaH..77..109E. doi:10.1127/0029-5035/2003/0077-0109.
  15. ↑ Nylander, W. (1855). "Essai d'une nouvelle classification des lichens, (second mémoire)" [Essay on a new classification of lichens, (second memoir)]. Mémoires de la Société Impériale des Sciences Naturelles de Cherbourg (in Latin). 3: 161–202 [193].
  16. ↑ Cáceres, Marcela Eugenia da Silva; Aptroot, André (2016). "First inventory of lichens from the Brazilian Amazon in Amapá State". The Bryologist. 119 (3): 250–265. doi:10.1639/0007-2745-119.3.250.
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