Bacidia

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Genus of lichen-forming fungi

title: "Bacidia" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["ramalinaceae", "lichen-genera", "lecanorales-genera", "taxa-named-by-giuseppe-de-notaris", "taxa-described-in-1846"] description: "Genus of lichen-forming fungi" topic_path: "general/ramalinaceae" source: "https://en.wikipedia.org/wiki/Bacidia" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Genus of lichen-forming fungi ::

| image = Surprise Lichen (4504246927).jpg | image_caption = Bacidia schweinitzii in Augusta, Georgia, USA | taxon = Bacidia | authority = De Not. (1846) | type_species = Bacidia rosella | type_species_authority = (Pers.) De Not. (1846) | subdivision_ranks = Species | subdivision = | synonyms_ref = | synonyms = *Sporacestra

  • Byssopsora
  • Thalloidima sect. Psorella
  • Psorella
  • Urophora
  • Bacidiomyces
  • Lichingoldia
  • Woessia

Bacidia is a genus of lichen-forming fungi in the family Ramalinaceae. These lichens are characterised by their crustose growth form, distinctive club-shaped reproductive structures called apothecia that contain long, needle-like spores, and their symbiotic partnership with green algae. Bacidia species typically grow on various substrates including tree bark, rock surfaces, and occasionally soil, and are distinguished from related genera by their specific spore characteristics and internal structures.

Taxonomy

The genus was circumscribed by Giuseppe De Notaris in 1846. In his original description, De Notaris distinguished Bacidia from the closely related genus Biatora based on several key characteristics. He noted that Bacidia species have apothecia (fruiting bodies) that are typically pink or reddish, or sometimes nearly cinnamon-coloured, with margins that persist throughout all developmental stages and are surrounded by a distinct border. The spores are rod-shaped with eight cells separated by cross-walls (septa), and are hyaline (transparent) and two-celled. De Notaris described the thallus as crustose, , and often effuse (spreading loosely), ranging from whitish to greyish-brown in colour. He included two species in his original circumscription: Bacidia rosella (the type species) and Bacidia carneola.

Description

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 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.

Like all lichens, Bacidia species represent a symbiotic partnership with algae. Their (algal partner) belongs to the 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.

The internal structure of the apothecia is diagnostic for the genus. They lack a (an outer layer containing algal cells) but possess a – 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.

The spore-producing cells (asci) are club-shaped to cylindrical-club-shaped and each contains eight . The spores themselves are colourless and typically long and narrow ( 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.

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.

Species

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/c6/Bacidia_heterochroa_-Flickr-pellaea(1).jpg" caption="Closeup of ''Bacidia heterochroa''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/9/95/Bacidia_schweinitzii_-Flickr-pellaea(4).jpg" caption="Closeup of ''Bacidia schweinitzii''"] ::

References

Gallery

Image:Bacidia schweinitzii-8.jpg|Cross section of an apothecium of B. schweinitzii, photographed through a compound microscope (x1000), showing a green epihymenium and a dark reddish-brown hypothecium Image:Bacidia schweinitzii-7.jpg|Acicular spore of B. schweinitzii, 65 x 6 micrometres, photographed through a compound microscope, x1000

References

  1. (2014). "New lichen species from termite nests in rainforest in Brazilian Rondônia and adjacent Amazonas". The Lichenologist.
  2. (2003). "''Bacidia iberica'', a new lichen from Spain, and its relationship to ''Bacidia rubella''". The Bryologist.
  3. (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''".
  4. (2006). "A new ''Bacidia'' with long-necked pycnidia from Central Europe". The Lichenologist.
  5. De Notaris, G.. (1846). "Frammenti lichenografici di un lavoro inedito". Giornale Botanico Italiano.
  6. (1995). "''Bacidia caesiovirens'', a new lichen species from western Europe". The Lichenologist.
  7. Ekman, Stefan. (2009). "''Bacidia rosellizans'', a new lichen species from the taiga belt". The Lichenologist.
  8. Fryday, Alan M.. (2019). "Eleven new species of crustose lichenized fungi from the Falkland Islands (Islas Malvinas)". The Lichenologist.
  9. (2018). "Four new species of ''Bacidia'' s.s. (Ramalinaceae, Lecanorales) in the Russian Far East". The Lichenologist.
  10. Kantvilas, G.. (2017). "Two species of ''Bacidia'' De Not. with pruinose apothecia from Kangaroo Island". Swainsona.
  11. (2018). "Studies on ''Bacidia'' (lichenized Ascomycota, Ramalinaceae) in temperate Australia, including Tasmania: saxicolous and terricolous species". The Lichenologist.
  12. (2016). "The faces of ''Bacidia schweinitzii'': molecular and morphological data reveal three new species including a widespread sorediate morph". The Bryologist.
  13. 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.
  14. Lendemer, James C.. (2020). "''Bacidia thiersiana'' (Ramalinaceae), a new species with lobaric acid widespread in southeastern North America". The Bryologist.
  15. (2007). "''Bacidia lobarica'' (Bacidiaceae, Lecanorales) sp. nov., a sorediate lichen from the southeastern U.S.A". The Bryologist.
  16. "Synonymy. Current Name: ''Bacidia'' De Not., G. bot. ital. 2(1.1): 189 (1846)". [[Species Fungorum]].

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