Agonimia

Taxonomy

The genus was circumscribed by the lichenologist Alexander Zahlbruckner in 1909, with Agonimia tristicula assigned as the type species. Zahlbruckner characterized the genus by its squamulose thallus lacking rhizines, pyrenocarpic apothecia with a terminal pore, and large muriform spores that are brownish to dark brown. He noted the genus was closely related to Endocarpon but distinguished it primarily by the absence of hymenial algae and differences in the thallus structure.

Description

Species of Agonimia grow as a crust that clings tightly to bark or rock. In most taxa this crust is built from tiny, grain-like clumps of algae and fungus (), but some develop minute scale-like lobes () or even coral-like branches; one outlier forms delicate, leaf-like up to 5 mm across. Where squamules are present their outer cells unite into a thin, skin-like layer (a ) that may be tinged brown and often bears one or more small warts (). In an extraordinary species these papillae stretch and fuse into stiff bristles. The thallus lacks the dead, protective film common in many lichens, except for a single species in which the outer cells collapse to leave a refractive crust. Squamules are usually fragile and crumble into powdery or irregular fragments that serve as asexual propagules; some species also shed —minute buds that break away—or produce structures resembling isidia or soredia. A distinct (a hyphal fringe at the margin) is absent or inconspicuous. The photosynthetic partner is a green algal cell of the type, measuring roughly 4–13 × 3.5–7.5 μm.

Fruiting bodies are flask-shaped perithecia that appear black, or grey-brown if overlain by a thin unpigmented film, and sit between the squamules or grains. Each perithecium is nearly spherical to barrel-shaped; the usual dark cap () is missing, so its wall () grades seamlessly outward. That wall is thick and stratified: a pigmented outer zone of rounded cells, a middle layer of similar but colourless tissue, and an inner layer of compressed, clear cells. The brown pigments turn grey-brown, reddish-brown, or greenish in potassium hydroxide solution. Within, the hymenial gel stains weakly with iodine—red in strong solution, blue in dilute—a property termed hemiamyloid. Only short ostiolar threads ( and ) line the neck; the longer interascal filaments found in many lichens are absent. The asci open by splitting their walls (), contain either two or eight spores, and show no iodine reaction. The ascospores are colourless, divided by multiple cross-walls (septa) into a brickwork pattern (), and may brown slightly when over-mature. Asexual reproductive bodies (pycnidial conidiomata) are rare; when present they release rod-shaped, colourless conidia. Thin-layer chromatography has so far failed to detect any secondary metabolites.

Species

, Species Fungorum (in the Catalogue of Life) accept 22 species of Agonimia:

• Agonimia abscondita P.M.McCarthy & Elix (2018) – Australia
• Agonimia allobata (Stizenb.) P.James (1992)
• Agonimia ascendens S.Y.Kondr., Lőkös & Hur (2018)
• Agonimia blumii S.Y.Kondr. (2015)
• Agonimia borysthenica Dymytrova, Breuss & S.Y.Kondr. (2011) – Ukraine
• Agonimia bryophilopsis (Vain.) Hafellner (2018)
• Agonimia cavernicola S.Y.Kondr., Lőkös & Hur (2015)
• Agonimia deguchii H.Harada (2013) – Japan
• Agonimia flabelliformis J.P.Halda, Czarnota & Guzow-Krzem. (2011) – Europe
• Agonimia foliacea (P.M.Jørg.) Lücking & B.Moncada (2017)
• Agonimia gelatinosa (Ach.) M.Brand & Diederich (1999)
• Agonimia globulifera M.Brand & Diederich (1999) – Europe
• Agonimia koreana Kashiw. & K.H.Moon (2008)
• Agonimia loekoesii S.Y.Kondr., J.P.Halda & Hur (2016)
• Agonimia octospora Coppins & P.James (1978)
• Agonimia opuntiella (Buschardt & Poelt) Vězda (1997)
• Agonimia repleta Czarnota & Coppins (2000) – Europe
• Agonimia sunchonensis S.Y.Kondr. & Hur (2018) – South Korea
• Agonimia tenuiloba Aptroot & M.Cáceres (2013) – Brazil
• Agonimia tristicula (Nyl.) Zahlbr. (1909)
• Agonimia vouauxii (B.de Lesd.) M.Brand & Diederich (1999)
• Agonimia yongsangensis S.Y.Kondr. & Hur (2018) – South Korea

References

References

1. (2013). "Pyrenocarpous lichens (except Trypetheliaceae) in Rondônia". The Lichenologist.
2. "''Agonimia''".
3. (1978). "New or Interesting British Lichens II". The Lichenologist.
4. (2000). "A new species of ''Agonimia'' and some interesting lichens from Gorce Mts (Western Beskidy Mts) new to Poland". Graphis Scripta.
5. (2011). "''Agonimia borysthenica'', a new lichen species (Verrucariales) from Ukraine". Österreichische Zeitschrift für Pilzkunde.
6. (2012). "A new ''Agonimia'' with flabelliform thallus from Europe". The Lichenologist.
7. (2013). "''Agonimia deguchii'' (lichenized Ascomycota, Verrucariaceae), a new saxicolous species from central Japan". Hikobia.
8. Kashiwadani. 2008. ''Lichenes Minus Cogniti Exsiccati'', Fasc. 15. :no. 351-no. 375
9. Kondratyuk, S.Y.. (2015). "''Agonimia blumii'' sp. nov. (Verrucariales, Lichen-Forming Ascomycota), a new taxon from Eastern Asia". Ukrainian Botanical Journal.
10. (2015). "New and noteworthy lichen-forming and lichenicolous fungi 2". Acta Botanica Hungarica.
11. (2016). "New and noteworthy lichen-forming and lichenicolous fungi 4". Acta Botanica Hungarica.
12. (2018). "New and noteworthy lichen-forming and lichenicolous fungi 7". Acta Botanica Hungarica.
13. (2018). "''Agonimia abscondita'' sp. nov. (lichenized Ascomycota, Verrucariaceae) from New South Wales, Australia". Australasian Lichenology.
14. (2023). "Verrucariales: Verrucariaceae, including the genera ''Agonimia'', ''Atla'', ''Bagliettoa'', ''Catapyrenium'', ''Dermatocarpon'', ''Endocarpon'', ''Henrica'', ''Heteroplacidium'', ''Hydropunctaria'', ''Involucropyrenium'', ''Merismatium'', ''Nesothele'', ''Normandina'', ''Parabagliettoa'', ''Placidopsis'', ''Placidium'', ''Placopyrenium'', ''Polyblastia'', ''Psoroglaena'', ''Sporodictyon'', ''Staurothele'', ''Thelidium'', ''Trimmatothele'', ''Verrucaria'', ''Verrucula'', ''Verruculopsis'' and ''Wahlenbergiella''". [[British Lichen Society]].
15. (1999). "New or interesting lichens and lichenicolous fungi from Belgium and Luxembourg. VIII". Lejeunia.
16. "Synonymy. Current Name: ''Agonimia'' Zahlbr., Öst. bot. Z. 59(9): 350 (1909)". [[Species Fungorum]].
17. Zahlbruckner, A.. (1909). "Vorarbeiten zu einer Flechtenflora Dalmatiens". Österreichische Botanische Zeitschrift.