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Bacidia

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Bacidia
Bacidia schweinitzii in Augusta, Georgia, USA
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Lecanorales
Family: Ramalinaceae
Genus: Bacidia
De Not. (1846)
Type species
Bacidia rosella
(Pers.) De Not. (1846)
Synonyms[1]

Bacidia is a genus of lichen-forming fungi in the family Ramalinaceae.

Taxonomy

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The genus was circumscribed by Giuseppe De Notaris in 1846.[2]

Description

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Bacidia is characterised by its crustose (crust-like) growth form. The main body (thallus) of these lichens typically appears as a thin layer that can be smooth, cracked, warty, or granular in texture. The thallus may sometimes develop specialised structures such as soredia (powdery propagules), isidia (small outgrowths), or tiny scale-like features. Its colour usually ranges from whitish to pale green, greenish-grey, pale grey, or fawn.[3]

Like all lichens, Bacidia species represent a symbiotic partnership with algae. Their photobiont (algal partner) belongs to the chlorococcoid group, featuring spherical or broadly oval-shaped cells. The fungal component produces distinctive reproductive structures called apothecia, which are disc-shaped and typically measure up to 1 mm across (occasionally reaching 1.3 mm). These apothecia sit directly on the thallus surface and can vary from flat to strongly convex in shape and come in various colours.[3]

The internal structure of the apothecia is diagnostic for the genus. They lack a thalline margin (an outer layer containing algal cells) but possess a true exciple – a protective layer composed of tightly packed, thick-walled fungal threads (hyphae) that have narrow internal channels and become gel-like. When stained with iodine, the spore-producing layer (hymenium) turns blue. Within this layer are specialised cells called paraphyses, which are rarely branched and often have swollen tips.[3]

The spore-producing cells (asci) are club-shaped to cylindrical-club-shaped and each contains eight ascospores. The spores themselves are colourless and typically long and narrow (filiform to needle-like) or S-shaped, though some species produce more cylindrical to spindle-shaped spores. These spores usually have three or more cross-walls (septa) when mature.[3]

The genus also produces asexual reproductive structures called pycnidia, which can be sunken into or sitting on the thallus surface. These structures produce colourless spores (conidia) of various shapes, which may sometimes have cross-walls. When tested with common chemical spot tests used in lichen identification, the thallus shows no reaction, though the reproductive structures may contain various pigments.[3]

Species

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Closeup of Bacidia heterochroa
Closeup of Bacidia schweinitzii

References

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  1. ^ "Synonymy. Current Name: Bacidia De Not., G. bot. ital. 2(1.1): 189 (1846)". Species Fungorum. Retrieved 29 October 2023.
  2. ^ De Notaris, G. (1846). "Frammenti lichenografici di un lavoro inedito". Giornale Botanico Italiano (in Italian). 2 (1): 174–224.
  3. ^ a b c d e Cannon, P.; Ekman, S.; Kistenich, S.; LaGreca, S.; Printzen, C.; Timdal, E.; Aptroot, A.; Coppins, B.; Fletcher, A.; Sanderson, N.; Simkin, J. (2023). Lecanorales: Ramalinaceae [revision 1], including the genera Bacidia, Bacidina, Bellicidia, Biatora, Bibbya, Bilimbia, Cliostomum, Kiliasia, Lecania, Megalaria, Mycobilimbia, Phyllopsora, Ramalina, Scutula, Thalloidima, Toninia, Toniniopsis and Tylothallia (PDF). Revisions of British and Irish Lichens. Vol. 35. p. 47. Open access icon
  4. ^ a b c d Gerasimova, Julia V.; Ezhkin, Aleksandr K.; Beck, Andreas (2018). "Four new species of Bacidia s.s. (Ramalinaceae, Lecanorales) in the Russian Far East". The Lichenologist. 50 (6): 603–625. doi:10.1017/s0024282918000397.
  5. ^ Kantvilas, G. (2017). "Two species of Bacidia De Not. with pruinose apothecia from Kangaroo Island". Swainsona. 31: 31–36.
  6. ^ Ekman, Stefan; Holien, Håkon (1995). "Bacidia caesiovirens, a new lichen species from western Europe". The Lichenologist. 27 (2): 91–98. doi:10.1006/lich.1995.0008.
  7. ^ a b c Lendemer, James C.; Harris, Richard C.; Ladd, Douglas (2016). "The faces of Bacidia schweinitzii: molecular and morphological data reveal three new species including a widespread sorediate morph". The Bryologist. 119 (2): 143–171. doi:10.1639/0007-2745-119.2.143.
  8. ^ Lendemer, James C. (2018). "Bacidia gullahgeechee (Bacidiaceae, Lecanoromycetes) an unusual new species potentially endemic to the globally unique Ashepoo-Combahee-Edisto River Basin of southeastern North America". The Bryologist. 121 (4): 536–546. doi:10.1639/0007-2745-121.4.536.
  9. ^ Aragón, Gregorio; Martínez, Isabel (2003). "Bacidia iberica, a new lichen from Spain, and its relationship to Bacidia rubella". The Bryologist. 106 (1): 143–146. doi:10.1639/0007-2745(2003)106[0143:bianlf]2.0.co;2.
  10. ^ a b c Kantvilas, Gintaras (2018). "Studies on Bacidia (lichenized Ascomycota, Ramalinaceae) in temperate Australia, including Tasmania: saxicolous and terricolous species". The Lichenologist. 50 (4): 451–466. doi:10.1017/s0024282918000154.
  11. ^ Printzen, Christian; Tønsberg, Tor (2007). "Bacidia lobarica (Bacidiaceae, Lecanorales) sp. nov., a sorediate lichen from the southeastern U.S.A". The Bryologist. 110 (3): 487–489. doi:10.1639/0007-2745(2007)110[487:blblsn]2.0.co;2.
  12. ^ a b Fryday, Alan M. (2019). "Eleven new species of crustose lichenized fungi from the Falkland Islands (Islas Malvinas)". The Lichenologist. 51 (3): 235–267. doi:10.1017/S0024282919000185.
  13. ^ Czarnota, Paweł; Coppins, Brian J. (2006). "A new Bacidia with long-necked pycnidia from Central Europe". The Lichenologist. 38 (5): 407–410. doi:10.1017/s0024282906005986.
  14. ^ Ekman, Stefan (2009). "Bacidia rosellizans, a new lichen species from the taiga belt". The Lichenologist. 41 (5): 481–487. doi:10.1017/s0024282909990144.
  15. ^ Aptroot, André; Cáceres, Marcela Eugenia da Silva (2014). "New lichen species from termite nests in rainforest in Brazilian Rondônia and adjacent Amazonas". The Lichenologist. 46 (3): 365–372. doi:10.1017/s0024282913000340.
  16. ^ Lendemer, James C. (2020). "Bacidia thiersiana (Ramalinaceae), a new species with lobaric acid widespread in southeastern North America". The Bryologist. 123 (1): 39–47. doi:10.1639/0007-2745-123.1.039.
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Wikimedia Commons has media related to Bacidia.
  • Cross section of an apothecium of B. schweinitzii, photographed through a compound microscope (x1000), showing a green epihymenium and a dark reddish-brown hypothecium
    Cross section of an apothecium of B. schweinitzii, photographed through a compound microscope (x1000), showing a green epihymenium and a dark reddish-brown hypothecium
  • Acicular spore of B. schweinitzii, 65 x 6 micrometres, photographed through a compound microscope, x1000
    Acicular spore of B. schweinitzii, 65 x 6 micrometres, photographed through a compound microscope, x1000
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