{{Short description|Genus of lichen-forming fungi}} {{Use dmy dates|date=October 2025}} {{Use Oxford spelling|date=October 2025}} {{Automatic taxobox | 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 = <ref name="Species Fungorum synonymy"/> | synonyms = *''Sporacestra'' {{au|A.Massal. (1860)}} *''Byssopsora'' {{au|A.Massal. (1861)}} *''Thalloidima'' sect. ''Psorella'' {{au|Müll.Arg. (1888)}} *''Psorella'' {{au|(Müll.Arg.) Müll.Arg. (1894)}} *''Urophora'' {{au|Sommerf. ex Arnold (1899)}} *''Bacidiomyces'' {{au|Cif. & Tomas. (1953)}} *''Lichingoldia'' {{au|D.Hawksw. & Poelt (1986)}} *''Woessia'' {{au|D.Hawksw. & Poelt (1986)}} }}
'''''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 {{lichengloss|cartilaginous}} 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, {{lichengloss|granular}}, 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''.<ref name="De Notaris 1846"/>
==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 {{lichengloss|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.<ref name="Cannon et al. 2023"/>
Like all lichens, ''Bacidia'' species represent a symbiotic partnership with algae. Their {{lichengloss|photobiont}} (algal partner) belongs to the {{lichengloss|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.<ref name="Cannon et al. 2023"/>
The internal structure of the apothecia is diagnostic for the genus. They lack a {{lichengloss|thalline margin}} (an outer layer containing algal cells) but possess a {{lichengloss|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.<ref name="Cannon et al. 2023"/>
The spore-producing cells (asci) are club-shaped to cylindrical-club-shaped and each contains eight {{lichengloss|ascospores}}. The spores themselves are colourless and typically long and narrow ({{lichengloss|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.<ref name="Cannon et al. 2023"/>
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.<ref name="Cannon et al. 2023"/>
==Species== thumb|right|Closeup of ''Bacidia heterochroa'' thumb|right|Closeup of ''Bacidia schweinitzii'' *''Bacidia absistens'' {{au|(Nyl.) Arnold (1871)}} *''Bacidia albogranulosa'' {{au|Malíček, Palice, Vondrák & Kukwa (2018)}} *''Bacidia alutacea'' {{au|(Kremp.) Zahlbr. (1926)}} *''Bacidia arceutina'' {{au|(Ach.) Arnold (1869)}} *''Bacidia areolata'' {{au|Gerasimova & A.Beck (2018)}}<ref name="Gerasimova et al. 2018"/> – Russian Far East *''Bacidia beckhausii'' {{au|Körb. (1860)}} *''Bacidia biatorina'' {{au|(Körb.) Vain. (1922)}} *''Bacidia brigitteae'' {{au|Kantvilas (2017)}}<ref name="Kantvilas 2017"/> – Kangaroo Island *''Bacidia caesiovirens'' {{au|S.Ekman & Holien (1995)}}<ref name="Ekman & Holien 1995"/> – western Europe *''Bacidia campbelliae'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia carneoglauca'' {{au|(Nyl.) A.L.Sm. (1911)}} *''Bacidia chrysocolla'' {{au|Olech, Czarnota & Llop (2009)}} *''Bacidia circumspecta'' {{au|(Norrl. & Nyl.) Malme (1895)}} *''Bacidia conspicua'' {{au|(C.Knight) Zahlbr. (1926)}} *''Bacidia convexa'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia cornea'' {{au|(With.) A.Massal. (1852)}} *''Bacidia coruscans'' {{au|S.Ekman (2004)}} *''Bacidia curvispora'' {{au|Coppins & Fryday (2007)}} *''Bacidia cylindrophora'' {{au|(Taylor) Kistenich, Timdal, Bendiksby & S.Ekman (2018)}} *''Bacidia depriestiana'' {{au|Lendemer & Keepers (2021)}} *''Bacidia effusa'' {{au|Trevis. (1856)}} *''Bacidia ekmaniana'' {{au|R.C.Harris, Ladd & Lendemer (2016)}}<ref name="Lendemer et al. 2016"/> *''Bacidia elongata'' {{au|Gerasimova & A.Beck (2018)}}<ref name="Gerasimova et al. 2018"/> – Russian Far East *''Bacidia entocosmensis'' {{au|(C.Knight) Zahlbr. (1926)}} *''Bacidia entodiaphana'' {{au|(C.Knight) Zahlbr. (1926)}} *''Bacidia fellhaneroides'' {{au|van den Boom (2018)}} *''Bacidia fluminensis'' {{au|(Malme) M.Cáceres & Lücking (2007)}} *''Bacidia fratruelis'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia friesiana'' {{au|(Hepp) Körb. (1860)}} *''Bacidia furfurella'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia fuscoviridis'' {{au|(Anzi) Lettau (1912)}} *''Bacidia gallowayi'' {{au|Coppins & Fryday (2007)}} *''Bacidia granosa'' {{au|(Tuck.) Zahlbr. (1926)}} *''Bacidia gullahgeechee'' {{au|Lendemer (2018)}}<ref name="Lendemer 2018"/> – United States *''Bacidia heterochroa'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia herbarum'' {{au|(Stizenb.) Arnold (1865)}} *''Bacidia iberica'' {{au|Aragón & I.Martínez (2003)}}<ref name="Aragón & Martínez 2003"/> – Spain *''Bacidia johnstoniae'' {{au|Elix (2009)}} *''Bacidia kekesiana'' {{au|R.C.Harris (2009)}} *''Bacidia killiasii'' {{au|(Hepp) D.Hawksw. (1983)}} *''Bacidia kurilensis'' {{au|Gerasimova, A.Ezhkin & A.Beck (2018)}}<ref name="Gerasimova et al. 2018"/> – Russian Far East *''Bacidia laurocerasi'' {{au|(Delise ex Duby) Zahlbr. (1926)}} *''Bacidia leucocarpa'' {{au|C.Knight (1880)}} *''Bacidia lithophila'' {{au|Kantvilas (2018)}}<ref name="Kantvilas 2018"/> – Australia *''Bacidia littoralis'' {{au|Kantvilas (2018)}}<ref name="Kantvilas 2018"/> – Australia *''Bacidia lividofusca'' {{au|(Nyl.) Zahlbr. (1926)}} *''Bacidia lividonigrans'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia lobarica'' {{au|Printzen & Tønsberg (2007)}}<ref name="Printzen & Tønsberg 2007"/> – United States *''Bacidia maccarthyi'' {{au|Kantvilas (2018)}}<ref name="Kantvilas 2018"/> – Australia *''Bacidia macquariensis'' {{au|C.W.Dodge (1968)}} *''Bacidia macrospora'' {{au|(C.Knight) Zahlbr. (1926)}} *''Bacidia marina'' {{au|Fryday (2019)}}<ref name="Fryday 2019"/> – Falkland Islands *''Bacidia microphyllina'' {{au|(Tuck.) Riddle (1923)}} *''Bacidia millegrana'' {{au|(Taylor) Zahlbr. (1888)}} *''Bacidia modestula'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia multicarpa'' {{au|van den Boom (2018)}} *''Bacidia multiseptata'' {{au|(Shirley) Zahlbr. (1926)}} *''Bacidia pallida'' {{au|Darb. (1912)}} *''Bacidia paramedialis'' {{au|M.Brand, Coppins, van den Boom & Sérus. (2009)}} *''Bacidia phyllopsoropsis'' {{au|R.C.Harris & Lendemer (2006)}} *''Bacidia placodioides'' {{au|Coppins & Fryday (2007)}} *''Bacidia polychroa'' {{au|(Th.Fr.) Körb. (1860)}} *''Bacidia prasinata'' {{au|(Zahlbr.) Coppins (1983)}} *''Bacidia pruinata'' {{au|Fryday (2019)}}<ref name="Fryday 2019"/> – Falkland Islands *''Bacidia punica'' {{au|Llop (2010)}} *''Bacidia purpurans'' {{au|R.C.Harris, Ladd & Lendemer (2016)}}<ref name="Lendemer et al. 2016"/> *''Bacidia pycnidiata'' {{au|Czarnota & Coppins (2006)}}<ref name="Czarnota & Coppins 2006"/> – central Europe *''Bacidia quadrilocularis'' {{au|Zahlbr. (1926)}} *''Bacidia raffii'' {{au|(Stirt.) Zahlbr. (1926)}} *''Bacidia rhodocardia'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia rosella'' {{au|(Pers.) De Not. (1846)}} *''Bacidia rosellizans'' {{au|S.Ekman (2009)}}<ref name="Ekman 2009"/> *''Bacidia rubella'' {{au|(Hoffm.) A.Massal. (1852)}} *''Bacidia rudis'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia sachalinensis'' {{au|Gerasimova, A.Ezhkin & A.Beck (2018)}}<ref name="Gerasimova et al. 2018"/> – Russian Far East *''Bacidia schweinitzii'' {{au|(Fr. ex Tuck.) A.Schneid. (1898)}} *''Bacidia scopulicola'' {{au|(Nyl.) A.L.Sm. (1911)}} *''Bacidia septosior'' {{au|(Nyl.) Zahlbr. (1926)}} *''Bacidia sigmospora'' {{au|van den Boom & Alvarado (2019)}} *''Bacidia sipmanii'' {{au|M.Brand, Coppins, van den Boom & Sérus. (2009)}} *''Bacidia sorediata'' {{au|Lendemer & R.C.Harris (2016)}}<ref name="Lendemer et al. 2016"/> *''Bacidia squamellosa'' {{au|(S.Ekman) Coppins & Aptroot (2008)}} *''Bacidia subareolata'' {{au|A.H.Ekanayaka & K.D.Hyde (2019)}} *''Bacidia subproposita'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia subturgidula'' {{au|(Nyl.) Zahlbr. (1926)}} *''Bacidia superbula'' {{au|(Müll.Arg.) Zahlbr. (1926)}} *''Bacidia superula'' {{au|(Nyl.) Hellb. (1896)}} *''Bacidia surinamensis'' {{au|van den Boom (2018)}} *''Bacidia termitophila'' {{au|Aptroot & M.Cáceres (2014)}}<ref name="Aptroot & Cáceres 2014"/> *''Bacidia thiersiana'' {{au|Lendemer (2020)}}<ref name="Lendemer 2020"/> – United States *''Bacidia thyrrenica'' {{au|Llop (2007)}} *''Bacidia vagula'' {{au|(Vain.) Zahlbr. (1926)}} *''Bacidia vallatula'' {{au|(Jatta) Kantvilas (1993)}} *''Bacidia veneta'' {{au|S.Ekman (2004)}} *''Bacidia vinicolor'' {{au|(Stirt.) Zahlbr. (1926)}} *''Bacidia viridescens'' {{au|(A.Massal.) Hellb. (1871)}}
==References== {{Reflist|refs=
<ref name="Aptroot & Cáceres 2014">{{cite journal |last1=Aptroot |first1=André |last2= Cáceres |first2=Marcela Eugenia da Silva |title=New lichen species from termite nests in rainforest in Brazilian Rondônia and adjacent Amazonas |journal=The Lichenologist |volume=46 |issue=3 |year=2014 |doi=10.1017/s0024282913000340 |pages=365–372 |bibcode=2014ThLic..46..365A }}</ref>
<ref name="Aragón & Martínez 2003">{{cite journal |last1=Aragón |first1=Gregorio |last2=Martínez |first2=Isabel |title=''Bacidia iberica'', a new lichen from Spain, and its relationship to ''Bacidia rubella'' |journal=The Bryologist |volume=106 |issue=1 |year=2003 |doi=10.1639/0007-2745(2003)106[0143:bianlf]2.0.co;2 |pages=143–146}}</ref>
<ref name="Cannon et al. 2023">{{cite book |last1=Cannon |first1=P. |last2=Ekman |first2=S. |last3=Kistenich |first3=S. |last4=LaGreca |first4=S. |last5=Printzen |first5=C. |last6=Timdal |first6=E. |last7=Aptroot |first7=A. |last8=Coppins |first8=B. |last9=Fletcher |first9=A. |last10=Sanderson |first10=N. |last11=Simkin |first11=J. |year=2023 |title=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'' |series=Revisions of British and Irish Lichens |volume=35 |page=47 |url=https://britishlichensociety.org.uk/sites/default/files/Ramalinaceae%20rev%201a_0.pdf}} {{OA}}</ref>
<ref name="Czarnota & Coppins 2006">{{cite journal |last1=Czarnota |first1=Paweł |last2=Coppins |first2=Brian J. |title=A new ''Bacidia'' with long-necked pycnidia from Central Europe |journal=The Lichenologist |volume=38 |issue=5 |year=2006 |doi=10.1017/s0024282906005986 |pages=407–410 |bibcode=2006ThLic..38..407C }}</ref>
<ref name="De Notaris 1846">{{cite journal |last=De Notaris |first=G. |year=1846 |title=Frammenti lichenografici di un lavoro inedito |journal=Giornale Botanico Italiano|volume=2 |issue=1 |pages=174–224 [189] |language=it |url=https://babel.hathitrust.org/cgi/pt?id=coo.31924066661756&seq=195}}</ref>
<ref name="Ekman & Holien 1995">{{cite journal |last1=Ekman |first1=Stefan |last2=Holien |first2=Håkon |title=''Bacidia caesiovirens'', a new lichen species from western Europe |journal=The Lichenologist |volume=27 |issue=2 |year=1995 |doi=10.1006/lich.1995.0008 |pages=91–98 |bibcode=1995ThLic..27...91E }}</ref>
<ref name="Ekman 2009">{{cite journal |last=Ekman |first=Stefan |title=''Bacidia rosellizans'', a new lichen species from the taiga belt |journal=The Lichenologist |volume=41 |issue=5 |year=2009 |doi=10.1017/s0024282909990144 |pages=481–487 |bibcode=2009ThLic..41..481E }}</ref>
<ref name="Fryday 2019">{{cite journal |last=Fryday |first=Alan M. |year=2019 |title=Eleven new species of crustose lichenized fungi from the Falkland Islands (Islas Malvinas) |journal=The Lichenologist |volume=51 |issue=3 |pages=235–267 |doi=10.1017/S0024282919000185 |bibcode=2019ThLic..51..235F }}</ref>
<ref name="Gerasimova et al. 2018">{{cite journal |last1=Gerasimova |first1=Julia V. |last2=Ezhkin | first2=Aleksandr K. | last3=Beck |first3=Andreas |title=Four new species of ''Bacidia'' s.s. (Ramalinaceae, Lecanorales) in the Russian Far East |journal=The Lichenologist |volume=50 |issue=6 |year=2018 |doi=10.1017/s0024282918000397 |pages=603–625 |bibcode=2018ThLic..50..603G }}</ref>
<ref name="Kantvilas 2017">{{cite journal |last=Kantvilas |first=G. |year=2017 |title=Two species of ''Bacidia'' De Not. with pruinose apothecia from Kangaroo Island |journal=Swainsona |volume=31 |pages=31–36}}</ref>
<ref name="Kantvilas 2018">{{cite journal |last1=Kantvilas |first1=Gintaras |title=Studies on ''Bacidia'' (lichenized Ascomycota, Ramalinaceae) in temperate Australia, including Tasmania: saxicolous and terricolous species |journal=The Lichenologist |volume=50 |issue=4 |year=2018 |doi=10.1017/s0024282918000154 |pages=451–466 |bibcode=2018ThLic..50..451K }}</ref>
<ref name="Lendemer et al. 2016">{{cite journal |last1=Lendemer |first1=James C. |last2=Harris |first2=Richard C. |last3=Ladd |first3=Douglas |title=The faces of ''Bacidia schweinitzii'': molecular and morphological data reveal three new species including a widespread sorediate morph |journal=The Bryologist |volume=119 |issue=2 |year=2016 |doi=10.1639/0007-2745-119.2.143 |pages=143–171}}</ref>
<ref name="Lendemer 2018">{{cite journal |last=Lendemer |first=James C. |title=''Bacidia gullahgeechee'' (Bacidiaceae, Lecanoromycetes) an unusual new species potentially endemic to the globally unique Ashepoo-Combahee-Edisto River Basin of southeastern North America |journal=The Bryologist |volume=121 |issue=4 |year=2018 |doi=10.1639/0007-2745-121.4.536 |pages=536–546}}</ref>
<ref name="Lendemer 2020">{{cite journal |last=Lendemer |first=James C. |title=''Bacidia thiersiana'' (Ramalinaceae), a new species with lobaric acid widespread in southeastern North America |journal=The Bryologist |volume=123 |issue=1 |year=2020 |doi=10.1639/0007-2745-123.1.039 |pages=39–47}}</ref>
<ref name="Printzen & Tønsberg 2007">{{cite journal |last1=Printzen |first1=Christian |last2=Tønsberg |first2=Tor |title=''Bacidia lobarica'' (Bacidiaceae, Lecanorales) sp. nov., a sorediate lichen from the southeastern U.S.A |journal=The Bryologist |volume=110 |issue=3 |year=2007 |doi=10.1639/0007-2745(2007)110[487:blblsn]2.0.co;2 |pages=487–489}}</ref>
<ref name="Species Fungorum synonymy">{{cite web |title=Synonymy. Current Name: ''Bacidia'' De Not., G. bot. ital. 2(1.1): 189 (1846) |url=https://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=475 |publisher=Species Fungorum |access-date=29 October 2023}}</ref>
}}
==Gallery== {{Commons category|Bacidia}} <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 </gallery>
{{Taxonbar|from=Q4838937}}
Category:Ramalinaceae Category:Lichen genera Category:Lecanorales genera Category:Taxa named by Giuseppe De Notaris Category:Taxa described in 1846